Your Cart is Empty
Introduction
Ever think about how the smallest things can sometimes have the biggest impact? That’s exactly what sprouts and microgreens do for your health. These tiny plants are more than just trendy toppings—they’re packed with nutrients that can transform your diet. A deep dive into the study "Sprouts and Microgreens as Novel Food Sources for Healthy Diets" by Ebert et al. (2022) reveals just how powerful these little greens can be.
Why Sprouts and Microgreens Are a Big Deal
Sprouts and microgreens aren’t just baby plants; they’re nutrient-dense powerhouses. Ebert’s study highlights how these microscale vegetables are not only packed with vitamins and minerals but also brimming with bioactive compounds that support overall health. Let’s break down why you should start adding more of these tiny greens to your plate:
What Makes Them So Nutrient-Dense?
Vitamins and Minerals Galore
Sprouts and microgreens are loaded with essential nutrients. We’re talking vitamins like C, E, and K, plus minerals like calcium, magnesium, and iron. These nutrients are crucial for everything from boosting your immune system to keeping your bones strong.
Antioxidant Powerhouses
These tiny plants are rich in antioxidants, which help protect your cells from damage caused by free radicals. Antioxidants are your body's defense against aging and diseases like cancer and heart disease.
Phytonutrients for Health
Sprouts and microgreens are full of phytonutrients—natural compounds that have been shown to reduce the risk of chronic diseases. These include polyphenols and glucosinolates, which have anti-inflammatory and cancer-preventive properties.
Clover Sprouts: Tiny but Mighty for Bone Health
Clover sprouts might be small, but they play a big role in keeping your bones healthy. According to the study, clover sprouts are particularly rich in isoflavones, a type of phytoestrogen that has been linked to improved bone health. Isoflavones can mimic estrogen in the body, which is important for maintaining bone density, especially as you age.
Adding clover sprouts to your diet could be an easy and natural way to support your bones. Whether you sprinkle them on salads, blend them into smoothies, or add them to your sandwiches, these sprouts are a simple yet powerful way to give your bones the nutrients they need.
How to Easily Add Sprouts and Microgreens to Your Diet
It’s easier than you might think to make these tiny greens a regular part of your meals. Here’s how:
Why You Should Start Growing Sprouts Today
The study by Ebert et al. (2022) makes one thing clear: sprouts and microgreens are an easy, effective way to boost your nutrition without needing to overhaul your diet. They’re quick to grow, packed with nutrients, and incredibly versatile in the kitchen. Whether you’re looking to improve your overall health, support specific aspects like bone health, or simply add a fresh twist to your meals, these tiny greens are the way to go.
At The Sprouting Company, we’re here to help you start your sprouting journey. Our sprouting kits make it easy to grow your own nutrient-packed sprouts and microgreens right at home. Why not take the first step today? Add these powerful little greens to your diet and start feeling the difference they can make.
Want to Learn More? Dive Into the Research
Curious about the full benefits of these tiny greens? Check out the study written below, titled "Sprouts and Microgreens as Novel Food Sources for Healthy Diets" by Ebert et al. (2022). It’s packed with information on why sprouts and microgreens should be a staple in any healthy diet.
Conclusion
Sprouts and microgreens might be tiny, but their impact on your health is huge. They’re packed with nutrients, easy to grow, and incredibly versatile. So why not add them to your diet today? Whether you’re looking to boost your overall health or support specific needs like bone health, these tiny greens have got you covered.
--
Full Study: Sprouts and Microgreens - Novel Food Sources for Healthy Diets
By Andreas W. Ebert
Abstract
With the growing interest of society in healthy eating, the interest in fresh, ready-to-eat, functional food, such as microscale vegetables (sprouted seeds and microgreens), has been on the rise in recent years globally. This review briefly describes the crops commonly used for microscale vegetable production, highlights Brassica vegetables because of their health-promoting secondary metabolites (polyphenols, glucosinolates), and looks at consumer acceptance of sprouts and microgreens. Apart from the main crops used for microscale vegetable production, landraces, wild food plants, and crops’ wild relatives often have high phytonutrient density and exciting flavors and tastes, thus providing the scope to widen the range of crops and species used for this purpose. Moreover, the nutritional value and content of phytochemicals often vary with plant growth and development within the same crop. Sprouted seeds and microgreens are often more nutrient-dense than ungerminated seeds or mature vegetables. This review also describes the environmental and priming factors that may impact the nutritional value and content of phytochemicals of microscale vegetables. These factors include the growth environment, growing substrates, imposed environmental stresses, seed priming and biostimulants, biofortification, and the effect of light in controlled environments. This review also touches on microgreen market trends. Due to their short growth cycle, nutrient-dense sprouts and microgreens can be produced with minimal input; without pesticides, they can even be home-grown and harvested as needed, hence having low environmental impacts and a broad acceptance among health-conscious consumers.
Introduction
Healthy diets are essential for nutrition and health. As defined by Neufeld et al., a healthy diet is “health-promoting and disease-preventing. It provides adequacy without excess, of nutrients and health-promoting substances from nutritious foods and avoids the consumption of health-harming substances.” About three billion people cannot afford healthy diets around the globe. This figure includes most people living in sub-Saharan Africa and South Asia. The Sustainable Development Goal 2 (SDG 2) ‘Zero Hunger’ of the United Nations calls for the eradication of hunger and all forms of malnutrition. All people ought to have access to safe, nutritious, and sufficient food all year round by 2030. The triple burden of malnutrition, i.e., undernutrition, micronutrient deficiency, and overnutrition, affects most nations around the globe. As incomes rise and food consumption patterns change, overnutrition from imbalanced diets increasingly becomes a concern in developed and developing countries.
Malnutrition is a high-risk factor for non-communicable diseases (NCDs), also known as chronic diseases. Diet-related NCDs, such as diabetes, cardiovascular disease, hypertension, stroke, cancer, and obesity, are escalating globally. Out of the estimated 40.5 million people killed by NCDs each year (71% of the annual deaths worldwide), approximately 32.2 million NCD deaths (80%) were attributable to cancers, cardiovascular diseases, chronic respiratory diseases, and diabetes. The remaining 8.3 million NCD deaths (20%) have other root causes. These figures illustrate the seriousness of diet-related diseases for the healthcare sector. Under SDG 3—‘Good Health and Well-Being’—SDG target 3.4 aims at reducing premature mortality from NCDs by one-third by 2030. The diversity and quality of food produced sustainably and made accessible to a wide range of consumers are decisive factors that enable substantial dietary shifts and, in turn, help to address SDG targets 2.1 and 3.4. A truly transformed global food system may not only provide universal access to healthy diets but may also co-deliver on climate and environmental SDGs.
The nutrition community frequently highlights the importance of fruits, vegetables, and nuts in combating the triple burden of malnutrition. The British Royal Society’s strategy to eliminate hidden hunger involves measures that promote increased access to fruits and vegetables to enhance dietary diversity. The World Health Organization (WHO) recommends a population-wide daily intake of 400 g of edible fruits and vegetables to prevent NCDs and alleviate several micronutrient deficiencies. This WHO recommendation translates to roughly five portions of fruits and vegetables per day. People able to enjoy more diverse diets, in general, also have better nutrition and health. A recent study analyzing data of a health survey in Great Britain revealed a robust inverse association between fruit and vegetable consumption and mortality.
Despite this general acceptance that fruits and vegetables are essential for a healthy diet, the authors of several studies concluded that current and projected fruit and vegetable production levels would fail to meet healthy consumption levels. Based on age-specific recommendations, only 40 countries representing 36% of the global population had adequate availability of fruits and vegetables in 2015. Although there was a sharp increase in vegetable consumption in sub-Saharan Africa over the last three decades, the combined fruit and vegetable intake (268 g) remains well below the WHO recommendation of 400 g.
With society’s growing interest in healthy eating and lifestyles, e.g., the Slow Food movement and the promotion of novel and superfoods, the interest in fresh, ready-to-eat functional and nutraceutical food has been on the rise in recent decades. In this context, microscale vegetables, i.e., sprouted seeds and microgreens, are becoming increasingly popular worldwide as fresh, ready-to-eat functional and nutraceutical food. They have great potential to diversify and enhance the human diet and address nutrient deficiencies due to their high content of phytochemicals.
Sprouts are commonly grown in the dark under high relative humidity. They are harvested when the cotyledons are still under-developed and true leaves have not begun to emerge, usually after 3–5 days from seed hydration. The entire plant (root, seed, and shoot) is consumed. Ancient Egyptians have already practiced sprouting seeds around 3000 B.C. During the germination process, the amount of antinutritive compounds (trypsin inhibitor, phytic acid, pentosan, tannin, and cyanides) decreases, while palatability and nutrient bioavailability, as well as the content of health-related phytochemicals (glucosinolates and natural antioxidants), are enhanced. While sprouts usually take less than a week to mature, microgreens are harvested for consumption within 10–20 days of seedling emergence. Microgreens, defined as tender, immature greens, are larger than sprouts, but smaller than baby vegetables or greens. They have a central stem with two fully developed, non-senescent cotyledon leaves and mostly one pair of small true leaves. The stem, cotyledons, and first true leaves are consumed. Microgreens have been produced in Southern California since the 1980s and have since gained popularity due to their vivid colors (like red and purple), delicate textures, and flavor-enhancing properties. They are used as garnishes in salads, sandwiches, soups, appetizers, desserts, and drinks and are highly appreciated because of their nutritional benefits. In vitro and in vivo research studies have demonstrated microgreens’ anti-inflammatory, anti-cancer, anti-bacterial, and anti-hyperglycemic properties, further strengthening their attractiveness as a new functional food that is beneficial to human health.
Commercial and home-grown microgreen production comprises several aspects: selecting appropriate species, growing systems, substrates, quality of seeds, seeding and germination, irrigation and fertilization, harvesting, phytosanitary quality, and post-harvest storage practices. Di Gioia et al. provided a detailed insight into these aspects. For a recent review of microgreen product types and production practices, readers may also consult Verlinden.
This comprehensive review describes the main crops used in microscale vegetable production and the factors that impact sprouts’ and microgreens’ nutritional and bioactive profile and their consumer acceptance. It also reflects on underutilized species (landraces, wild food plants, and crops’ wild relatives) that offer the scope to widen the range of crops used for this purpose. In addition, this paper reviews the effects of plant growth stages on the nutritional and bioactive composition of edible plant parts.
Crops Commonly Used for Microscale Vegetable Production
Sprouts and microgreens are grown from the seeds of many crops, such as legumes, cereals, pseudo-cereals, oilseeds, vegetables, and herbs; Table 1. The significant traits of interest for consumers are the appearance, texture, flavor, phytochemical composition, and nutritional value of sprouts and microgreens. Most crops are grown for sprouts and microgreens, except for beans and some oilseed tree species that are commonly grown as sprouts only. Mungbean and soybean sprouts have long been an essential, year-round component of Asian and vegetarian dishes. In recent decades, mungbean sprouts have become increasingly popular in the Americas, Europe, and Africa. They are commonly recognized as “bean sprouts,” although this group comprises several different crops. Most food and forage legumes are known for their high nutritional value and an abundance of minerals and secondary metabolites. Sprouted seeds and microgreens often contain higher concentrations of bioactive compounds than raw seeds.
Sprouting cereal grains enhances their nutritional value, especially when applying a sprouting duration of at least 3 to 5 days. The sprouting process activates hydrolytic enzymes and releases nutrients from their phytate chelates, making them bioavailable; in addition, vitamins are synthesized and accumulate. Sprouted grains are also used in many staple foods such as bread, pasta, noodles, and breakfast flakes, but food processing often compromises their nutritional value.
Pseudocereals are underutilized food crops that are receiving increasing attention as highly nutritious and functional foods. Among those, amaranth, quinoa, and buckwheat are increasingly becoming popular for sprout and microgreen production. Apart from soybean, peanut (listed under legumes), and mustard (classified here as a vegetable), almond, hazelnut, linseed, sesame, and sunflower are other oilseed crops that one can use for sprouting or microgreen production. Among the group of vegetables and herbs, members of the Brassicaceae family are widely used for sprouting and microgreen production, followed by crops of the Apiaceae, Fabaceae, and Amaranthaceae families.
Bioactive Composition and Potential Health Effects of Brassica Microscale Vegetables
As evident from the crop groups listed, the Brassicaceae family comprises a wide range of crops commonly used for microscale vegetable production. The intrinsic qualities of Brassica vegetables, including their color, aroma, taste, and health properties, are profoundly determined by secondary plant metabolite profiles and their concentrations in plant tissues. Brassica vegetables are rich sources of bioactive compounds, such as glucosinolates (GSLs), polyphenols, anthocyanins, ascorbic acid, carotenoids, and tocopherols. The biosynthesis of secondary plant metabolites is closely linked to plant protection and defense mechanisms and can be modulated by environmental and agronomical factors. Those factors may significantly change the concentration of secondary plant metabolites with up to 570-fold increases for specific compounds, such as isothiocyanates.
Among the bioactive compounds of Brassica vegetables, polyphenols and GSLs have been widely studied due to their known health-promoting effects, including the impact of cooking methods on the retention of these essential compounds. In addition, polyphenols are good sources of natural antioxidants, which help decrease the risk of diseases associated with oxidative stress. GSLs, defined as aliphatic, aromatic, or indolic based on their side chains, are important secondary metabolites that are predominantly found in Brassica crops.
The cancer-preventive potential of kale (B. carinata) has been demonstrated through in vitro studies which indicated the protection of human liver cells against aflatoxin in vitro. Similar results have been obtained with broccoli (Brassica oleracea var. italica) and watercress (Nasturtium officinale). Isothiocyanates—hydrolysis products of GSLs—extracted from broccoli and watercress sprouts suppressed human breast cancer cells in vitro. In addition, extracts of 3-day-old broccoli sprouts were highly effective in reducing the incidence, multiplicity, and rate of development of mammary tumors in rats treated with the carcinogen DMBA (7,12-dimethylbenz[a]anthracene). Therefore, diets high in Brassica vegetables may contribute to the suppression of carcinogenesis, and this effect is at least partly related to their relatively high content of GSLs.
Among five of the microgreen species of the Brassicaceae, namely broccoli (Brassica oleracea var. italica), daikon (Raphanus raphanistrum subsp. sativus), mustard (Brassica juncea), rocket salad (Eruca vesicaria), and watercress (Nasturtium officinale), broccoli had the highest polyphenol, carotenoid, and chlorophyll contents, as well as strong antioxidant power. Mustard microgreens showed high ascorbic acid and total sugar contents. On the other hand, rocket salad exhibited the lowest antioxidant content and activity among the five evaluated microgreen crops.
Broccoli, curly kale, red mustard, and radish microgreens are good sources of minerals. They provide considerable amounts of vitamin C and total carotenoids, the latter being higher than in adult plants. In digestion studies, total soluble polyphenols and total isothiocyanates showed a bioaccessibility of 43–70% and 31–63%, respectively, while the bioaccessibility of macroelements ranged from 34–90%. Among the four microgreen crops tested, radish and mustard presented the highest bioaccessibility of bioactive compounds and minerals.
Consumer Acceptance of Sprouts and Microgreens and Nutritional Profile of Microscale Vegetables
Six commonly grown and consumed microgreen species were tested for consumer acceptance: arugula (Eruca sativa), broccoli (Brassica oleracea var. italica), red cabbage (B. oleracea var. capitata), bull’s blood beet (Beta vulgaris), red garnet amaranth (Amaranthus tricolor), and tendril pea (Pisum sativum). All six microgreen crops received high ratings for appearance acceptability; hence they could easily be used to enhance the visual appearance of meals if they have the appropriate sensory attributes. Among the six microgreen crops evaluated, broccoli, red cabbage, and tendril pea received the highest overall acceptability score with similar trends for taste and texture.
In a similar approach, six microgreen species were evaluated for their sensory attributes and nutritional value. The species included mustard, peppercress, China rose radish, bull’s blood beet, red amaranth, and opal basil. Overall, all six microgreen species received “good” to “excellent” consumer acceptance ratings and showed high nutritional quality. Among those six crops, bull’s blood beet received the highest acceptability score regarding flavor and overall eating quality, while peppercress received the lowest score. The highest concentrations of total ascorbic acid and tocopherols were detected in China rose radish, the highest contents of total phenolics and phylloquinone (vitamin K1) in opal basil, and the highest content of carotenoids in red amaranth.
Consumer acceptance studies conducted at the World Vegetable Center compared amaranth (Amaranthus tricolor) landraces with commercially available cultivars. A Genebank accession consistently received the highest ratings for appearance, texture, taste, and general acceptability at the sprout, microgreen, and fully grown stages.
A consumer acceptance study in India included carrot, fenugreek, mustard, onion, radish, red roselle, spinach, sunflower, fennel, and French basil. The organoleptic acceptability of all ten microscale vegetables ranged from very good to excellent.
The high appreciation of microgreens compared to mature vegetables might also be related to their aroma profile. Recent research has shown that the aroma profile of Perilla frutescens var. frutescens (Chinese basil or perilla; green leaves) and P. frutescens var. crispa (red leaves) is much higher at the microgreens stage than at the later adult stage. Both varieties have a clearly distinct aroma profile at the microgreen stage. The red variety emitted a citrusy, spicy, and woody aroma, while the green type produced a fruity, sweet, spicy, and herbaceous aroma at the microgreens stage. After the microgreen stage, at the age of four weeks, green Chinese basil no longer emitted any aroma volatiles. Hence, the aroma profile of Chinese basil leaves at the microgreen stage is clearly variety-specific and not related to the content of total phenols or the antioxidant capacity of the leaves.
Attempting a nutritional determination among five Brassicaceae microgreen crops (broccoli, daikon, mustard, rocket salad, and watercress), broccoli excelled. Broccoli microgreens had the highest content of isothiocyanates, known for their cancer-preventing abilities, and displayed the most potent antioxidant power. Broccoli microgreens exhibited the overall best nutritional profile and, therefore, are considered as one of the most promising functional food species.
Based on the determination of the contents of 11 nutrients and vitamins, as well as the anti-nutrient oxalic acid, and their relative contribution to the diet as per the estimated daily intake published in the United States Department of Agriculture (USDA) database for green leafy vegetables, a nutrient quality score (NQS) was computed to assess the nutritional quality of ten culinary microgreen species. The selected species included vegetable crops (spinach, carrot, mustard, radish, roselle, and onion); leguminous crops (fenugreek); oleaginous crops (sunflower); and aromatic species (French basil and fennel). All microgreen crops are moderate to good sources of protein, dietary fiber, and essential nutrients. Concerning their vitamin content, the studied microgreens are excellent sources of ascorbic acid, vitamin E, and beta-carotene (pro-vitamin A). In general, microgreens had low levels of oxalic acid, which is a predominant anti-nutrient in mature leafy vegetables. Based on the calculated NQS, radish microgreens showed the highest nutrient density, followed by French basil and roselle microgreens. On the other hand, fenugreek and onion microgreens are the least nutrient dense. Furthermore, the calculated NQS revealed that all microgreens were 2–3.5 times more nutrient dense than mature leaves of spinach cultivated under similar conditions.
While high nutrient density and high phytochemical content are considered a must in sprouts and microgreens, these microscale vegetables must also have high consumer acceptability in flavor attributes and visual appearance. Based on organoleptic and nutritional properties, different microgreen species were assessed regarding consumer acceptance of appearance, texture, and flavor. The 12 microgreen species included in the studies were amaranth, coriander, cress, green basil, komatsuna, mibuna, mizuna, pak choi, purple basil, purslane, Swiss chard, and tatsoi. The results revealed that while the visual appearance of the microgreens played a role, the flavor and texture of microgreens were the main determining factors for consumer acceptance. In general, low astringency, sourness, and bitterness enhanced the consumer acceptability of microgreens. Among the 12 examined microgreen species, mibuna (Brassica rapa subsp. nipposinica) and cress (Lepidium sativum) received the lowest consumer acceptance score, while Swiss chard (Beta vulgaris subsp. vulgaris) and coriander (Coriandrum sativum) were the most appreciated microscale vegetables.
Unfortunately, phenolic content strongly correlates with flavor attributes such as sourness, astringency, and bitterness. Therefore, microscale vegetables rich in phenolics, such as red cabbage (Brassica oleracea var. capitata), sorrel (Rumex acetosa), and peppercress (Lepidium bonariense), in general, receive a low consumer acceptability score. However, rich content in minerals, vitamins, phenolics, and antioxidant activity can also be found in species of more acceptable tastes, such as amaranth, coriander, and Swiss chard. As shown with the above examples, identifying microgreen species that satisfy both sensory and health attributes at a high degree remains a challenge since acrid taste’s acceptability is subject to both inherited and acquired taste factors. Providing concise, crop-specific information about the culinary uses and the outstanding nutritional and health benefits of microscale vegetables might increase consumer interest. Such information might convince them to try products of high nutritional value but less agreeable tastes, eventually broadening the overall consumer acceptability of such produce.
Underutilized Species with Potential for Microscale Vegetable Production to Enhance Nutrition Security
Breeding for high yield, appearance, etc., may sometimes unintentionally lead to a decline in essential nutrients and phytochemicals. This hypothesis is supported by a review study conducted on 43 garden crops that revealed a statistically reliable reduction in six nutritional factors (protein, Ca, P, Fe, riboflavin, and ascorbic acid) between 1950 and 1999 based on USDA food composition data for this period. These changes can be explained by changes in the crop varieties cultivated during this same period. Similar trends have been observed in wheat grain and potato tubers. Some modern varieties of vegetables and grains might have lower contents in some nutrients than older varieties due to a dilution effect of increased yield by the accumulation of carbohydrates without a proportional increase in certain other nutrients. Nonetheless, it is argued that eating the WHO-recommended daily servings of fruits and vegetables would provide adequate nutrition. However, most countries and the majority of the global population, especially in sub-Saharan Africa, are still well below the WHO-recommended daily intake levels of fruits and vegetables.
When aiming for high phytonutrient density and exciting flavors and tastes, it might well be worth exploring farmers’ landraces, wild food plants, or populations found in a semi-wild or wild state, such as crops’ wild relatives. Such species are often part of the conservation focus of national genebanks, e.g., the genebanks maintained by the USDA in the USA, or international ones, e.g., the Genebank maintained by the World Vegetable Center (WorldVeg). This idea of exploring landraces, wild food plants, or crops’ wild relatives for microscale vegetable production has recently gained impetus.
The microgreens of wild plants and culinary herbs could constitute a source of functional food with attractive aromas, textures, and visual appeal, which could provide health benefits due to their elevated nutraceutical value and could be exploited in new gastronomic trends. Studies of 13 wild edible plants from 11 families revealed that their outstanding nutritional value would merit promotion to provide health benefits. Fennel, which is commonly used for sprout and microgreen production, has higher radical scavenging activity, total phenolic, and total flavonoid contents in its wild form compared to medicinal and edible fennel. Variations in the phytochemical content of wild fennel obtained from different geographical areas were also reported. For broccoli, kale, and pak choi, there is a variation of the concentrations of secondary plant metabolites among cultivars with ranges up to 10-fold.
Studies involving three wild leafy species, Sanguisorba minor (salad burnet), Sinapis arvensis (wild mustard), and Taraxacum officinale (common dandelion), at the microgreen and baby green stages recognized the potential of those wild edible plants in achieving competitive yields and contributing to the dietary intake of nutritionally essential macro- and microelements, as well as bioactive compounds.
Sprouted seeds of chia (Salvia hispanica), golden flax, evening primrose, phacelia, and fenugreek are an excellent source of health-promoting phytochemicals, especially antioxidants and minerals. Germination significantly increased the total phenolic content, antioxidant activity, and the content of phenolic acids and flavonoids in sprouts compared to the ungerminated seed of the mentioned species.
A rather exotic medicinal vegetable with a mild, bitter flavor is Korean ginseng (Panax ginseng). Sprouts of this crop can be grown to whole plants in 20 to 25 days in a soilless cultivation system. Their main bioactive compounds are ginsenosides, which have anti-cancer, anti-diabetic, immunomodulatory, neuroprotective, radioprotective, anti-amnestic, and anti-stress properties. Korean ginseng sprouts can be included in salads, milkshakes, sushi, soups, and tea. It is also used in health food supplements and cosmetics.
In summary, underutilized plants, such as farmers’ landraces, wild food plants, or crops’ wild relatives, often conserved in genebanks, might offer valuable opportunities to produce sprouts and microgreens with high nutritional value and exciting flavors and tastes, thus meeting the demands of health-conscious consumers. However, additional research efforts are required to determine whether the germination performance of these novel plant materials is satisfactory for commercial microscale vegetable production.
Variation of Nutritional Value and Content of Phytochemicals According to Plant Growth Stages
Numerous studies have shown that the nutritional value and content of phytochemicals of vegetables and other crops may vary with plant growth and development. The concentration of essential minerals, vitamins, bioactive compounds, and antioxidant activity often increases in this sequence: raw seeds—sprouted seeds—microgreens. In many cases, sprouts and microgreens even exceed the nutritional value of fully grown plants. Examples of variations in the content of essential nutrients, vitamins, and phytochemicals according to plant growth stages (seeds, sprouts, microgreens, baby leaves, and fully grown) are discussed below.
Research has shown that seed germination can increase total phenolic content (TPC) levels and antioxidant activity in mungbean (Vigna radiata), adzuki bean (Vigna angularis), black bean (Vigna cylindrica), soybean (Glycine max), peanut (Arachis hypogaea), radish (Raphanus sativus), broccoli (Brassica oleracea var. italica), and sunflower (Helianthus annuus). Among the 13 phenolic compounds detected in high concentrations, sinapic acid, ellagic acid, ferulic acid, and cinnamic acid showed high correlations with antioxidant activities. High TPC levels have also been confirmed in sprouted seeds of several underutilized species, such as chia (Salvia hispanica), golden flax (Linum flavum), phacelia (Phacelia tanacetifolia), fenugreek (Trigonella foenum-graecum), and evening primrose (Oenothera biennis). Evening primrose showed the highest TPC values and antioxidant activity among those underutilized species, both for sprouts and seeds. Compared to dry grains, seed sprouting enhanced TPC levels of chia, golden flax, phacelia, and fenugreek.
Compared to ungerminated seeds, amaranth and quinoa sprouts showed higher contents of total flavonoids, phenolics, and antioxidant activity. A substantial increase in vitamin C (ascorbic acid) content was observed from amaranth sprouts to microgreens (2.7-fold) and from amaranth microgreens to fully grown leafy amaranth (2.9-fold). Higher ascorbic acid and α-tocopherol levels were detected in spinach microgreens compared to the mature vegetable stage. The often-higher ascorbic acid (vitamin C) content of microgreens compared to sprouts can be explained by the presence of photosynthetic activity, which is absent in sprouts. Ascorbate is synthesized from photosynthetic hexose products and plays a significant role in photosynthesis as an enzyme cofactor (including in the synthesis of plant hormones and anthocyanins) and cell growth regulation. Red cabbage microgreens had a 6-fold higher concentration of total ascorbic acids than mature cabbage. With 131.6 mg/100 g fresh weight, garnet amaranth also had a much higher total ascorbic acid concentration than its mature counterpart. With some exceptions, most of the microgreens studied showed higher total ascorbic acid concentration than their mature counterparts.
The ascorbic acid content of fenugreek, spinach, and roselle microgreens reached 120%, 127%, and 119%, respectively, of their fully grown, mature stage. The ascorbic acid levels of the studied microgreens ranged from 29.9–123.2 mg/100 g, and therefore, were comparable to those of citrus fruits, which are generally known to be rich sources of vitamin C.
Tocopherols and tocotrienols belong to the vitamin E family. The α-tocopherol levels of fenugreek, spinach, and roselle microgreens were significantly higher than those of their respective mature leaves. Among the microgreens evaluated, green daikon radish microgreens exhibited the highest tocopherol concentrations in the α- and γ-forms, followed by coriander, opal radish, and peppercress. Although golden pea tendrils had the lowest tocopherol concentrations of α and γ, these values were still higher than those determined in mature spinach leaves.
In general, the microgreens’ phylloquinone (vitamin K1) content is relatively high compared to the corresponding values of mature vegetables. A total of 18 out of 25 commercially grown microgreens contain similar or greater phylloquinone concentrations than the commonly consumed vegetable broccoli. Green (pea tendrils) or bright red (garnet amaranth) microgreens often exhibit higher phylloquinone concentrations than yellow microgreens (popcorn and golden pea).
Among 25 microgreens, wide ranges of β-carotene concentrations were detected. Red sorrel exhibited the highest β-carotene concentration, while golden pea tendrils and popcorn microgreens had the lowest β-carotene concentrations. With 11.7 mg/100 g fresh weight, coriander microgreens had the second-highest β-carotene concentration, a 3-fold higher concentration than found in mature coriander leaves. With 11.5 mg/100 g fresh weight, red cabbage microgreens had a 260-fold higher β-carotene content than that found in mature red cabbage. Except for golden pea tendrils and popcorn shoots, most microgreens were rich in β-carotene. Coriander and red cabbage microgreens had 11.2- and 28.6-fold higher lutein/zeaxanthin concentrations, respectively, than their mature crops. Coriander microgreens also exhibited the highest violaxanthin concentration.
Microscale Brassica vegetables (sprouts, microgreens, and baby leaves) of broccoli, kale, and radish are good sources of health-promoting phytochemicals with high antioxidant capacities. These are, in general, found in higher concentrations at the sprout and microgreen stage than in the respective adult edible plant organs. In one study, polyphenol profiles differed among the three novel food types (sprouts, microgreens, and baby leaves) and cultivars within the same food type. Sprouts showed the highest total polyphenol content of the broccoli cultivars and the highest antioxidant capacity of all three cultivars studied. Ascorbic acid levels varied significantly among the studied cultivars and the three plant growth stages. Microgreens of the landrace ‘Broccolo Nero’ presented the highest ascorbic acid values. Chicory, lettuce, and broccoli microgreens showed higher amounts of α-tocopherol and carotenoids than mature vegetables. Health-promoting phytochemicals are more concentrated in cruciferous sprouts (e.g., broccoli and red radish) than in their respective adult plant edible organs.
In the Fabaceae vegetables chickpea and mungbean, the content of total phenolics and vitamins and the antioxidant activity increased in the sequence of raw seeds, sprouts, and microgreens. The sprouting of mungbean seeds increased total phenolic and flavonoid (TF) levels and the antioxidant activity (AA) when compared to ungerminated seeds. Compared to sprouts, flaxseed (Linum usitatissimum) microgreens exhibited higher chlorophyll, carotenoid, and phenol contents, as well as higher antioxidant capacity.
Studies on nine leafy summer vegetables revealed variations in mineral content and antioxidant activity at the microgreen and mature stages. While microgreens had a higher content of potassium and zinc, no specific trend was observed for copper, iron, and manganese. Microgreens of jute (Corchorus olitorius) and cucumber (Cucumis sativus) presented higher ascorbic acid levels compared to their mature stages. The ascorbic acid content of water spinach (Ipomoea aquatica) was comparable at the microgreen and mature stages. For other vegetable species, including bottle gourd (Lagenaria siceraria), pumpkin (Cucurbita moschata), amaranth (Amaranthus tricolor), Malabar spinach (Basella alba), radish (Raphanus raphanistrum), and beet (Beta vulgaris var. bengalensis), the mature plants showed higher ascorbic acid contents in comparison with the microgreen stage.
Although the ascorbic acid content is often higher at the adult stage than the microgreen stage, the human body cannot appropriately benefit from this rich ascorbic acid source. Leafy vegetables at the mature stage are generally consumed after cooking, and ascorbic acid is known to be thermolabile. In contrast, microgreens are usually consumed fresh; hence, the human body can fully benefit from this ascorbic acid source in microgreens. Jute (Corchorus olitorius) and water spinach (Ipomoea aquatica) are richer sources of phenolics and flavonoids compared to commonly consumed vegetable crops such as broccoli, lettuce, and carrot at the mature stage.
Studies have shown that hydroponically grown lettuce and cabbage microgreens are more nutrient-rich than their corresponding mature vegetables. The average nutrient ratio of vermicompost-grown broccoli microgreens to fully grown broccoli was 1.73. Based on this experimentally verified ratio, it has been argued that one would need to eat significantly less mass of microgreens to obtain the same amount of minerals present in a serving of raw broccoli florets. Furthermore, broccoli microgreens would require much less water to grow than a nutritionally equivalent amount of broccoli vegetable in fields.
High nutritional content has also been reported in 2-week-old butterhead lettuce (Lactuca sativa var. capitata) microgreens, which contain higher levels of essential minerals such as calcium, magnesium, iron, manganese, zinc, selenium, and molybdenum compared to mature lettuces. High nitrate levels may accumulate in leafy vegetable crops, and breeders aim to breed leafy vegetables with low nitrate contents. Lettuce microgreens have much lower nitrate content than mature lettuces and are thus safe for consumption by infants and children. A lower concentration of nitrates in Swiss chard (Beta vulgaris subsp. vulgaris) and rocket (Eruca sativa) microgreens than typically found in the corresponding baby leaf or adult vegetables has also been reported. Withholding nutrient supplementation in the growing media of microgreens is another option that almost completely suppresses nitrate accumulation.
Protection against carcinogenesis, mutagenesis, and other forms of toxicity can be achieved by the induction of phase 2 detoxification enzymes. Large quantities of inducers of enzymes that protect against carcinogens can be delivered through dietary means by small amounts of young crucifer sprouts. For example, three-day-old broccoli sprouts contained as much inducer activity as 10–100 times larger quantities of the corresponding mature vegetable. This is a tremendous health benefit of the Brassica microscale vegetables, which are easily accessible to consumers.
In addition to Brassica microscale vegetables, okra (Abelmoschus esculentus) and water spinach (Ipomoea aquatica) sprout extracts also exhibited anti-proliferative effects on gastric cancer, hepatoma, and melanoma cell lines. However, alfalfa and pea sprout extracts showed negligible anti-cancer activity. It has been hypothesized that the water-soluble bioactive compounds in okra and water spinach sprouts are responsible for the observed anti-cancer activities.
Besides macro- and microelements, vitamins, polyphenols, and other bioactive compounds, dietary fiber (DF) is another essential component of the human diet. The macromolecules of DF mainly consist of plant cell wall components, polysaccharides, and lignin. They resist digestion by endogenous enzymes in the human gut and promote the satiety sensation. The health benefits of DF include weight loss, prevention and treatment of constipation, control of serum cholesterol levels, and improved glucose tolerance, among others. In addition, the ability of DF to bind toxic compounds has been recognized as a protective mechanism against cancer.
Studies indicated relatively low DF contents in broccoli and chicory microgreens. In contrast, other studies reported higher total dietary fiber (TDF) contents in sunflower and fennel microgreens, with TDF values comparable to those of mature leafy vegetables known for their high TDF contents. It is obvious that with the increasing age of microgreens, their TDF content is expected to increase as well.
The examples in this section indicate that microscale vegetables are, in general, nutrient-dense and rich in phytochemicals, often with a reduced level of antinutrients as compared to the adult growth stage, hence constituting an attractive component as a functional food in the diet of health-conscious consumers.
Environmental and Priming Factors Impacting the Nutritional Value and Content of Phytochemicals in Microscale Vegetables
The nutritional value and content of phytochemicals in microscale vegetables are influenced by various environmental and priming factors, including the growth environment, growing substrates, imposed environmental stresses, seed priming and biostimulants, biofortification, and the effect of light in controlled environments. These factors can significantly impact the concentration and bioavailability of essential nutrients and bioactive compounds, thereby influencing the overall health benefits of sprouts and microgreens.
Growth Environment and Substrates
The growth environment, including temperature, humidity, and light, plays a crucial role in determining the nutritional quality of microscale vegetables. For instance, controlled environment agriculture (CEA) systems, such as hydroponics, aeroponics, and vertical farming, allow for precise control over these environmental factors, leading to enhanced nutritional value and phytochemical content in sprouts and microgreens. The type of growing substrate also affects the nutritional composition of microscale vegetables. Common substrates include soil, peat, coconut coir, and various soilless media. The choice of substrate can influence root development, nutrient uptake, and the overall growth of the plants.
Environmental Stresses
Imposed environmental stresses, such as drought, salinity, and temperature extremes, can induce the production of secondary metabolites in plants, including phytochemicals with antioxidant properties. These stresses can enhance the nutritional profile of microscale vegetables by increasing the concentration of beneficial compounds such as polyphenols, flavonoids, and glucosinolates. However, the intensity and duration of stress must be carefully managed to avoid detrimental effects on plant growth and yield.
Seed Priming and Biostimulants
Seed priming is a technique used to enhance seed germination and seedling vigor by pre-treating seeds with various agents such as water, chemicals, or biological agents. Primed seeds often exhibit faster and more uniform germination, leading to improved growth and development of microscale vegetables. Biostimulants, including humic substances, seaweed extracts, and beneficial microorganisms, can further enhance the nutritional value and phytochemical content of sprouts and microgreens by promoting plant growth and increasing the accumulation of bioactive compounds.
Biofortification
Biofortification is the process of increasing the nutritional content of crops through conventional breeding, genetic modification, or agronomic practices. In the context of microscale vegetables, biofortification can be achieved by enriching the growing medium with specific nutrients, such as iodine, iron, zinc, or selenium, to enhance the micronutrient content of sprouts and microgreens. This approach has the potential to address micronutrient deficiencies in the human diet, particularly in regions where access to diverse and nutrient-rich foods is limited.
Light in Controlled Environments
Light is a critical factor influencing the growth, development, and nutritional quality of microscale vegetables. In controlled environments, such as indoor farms or growth chambers, light intensity, duration, and wavelength can be manipulated to optimize the production of phytochemicals. For example, specific wavelengths of light, such as red and blue light, have been shown to increase the accumulation of anthocyanins, carotenoids, and other bioactive compounds in microscale vegetables. The use of light-emitting diodes (LEDs) in controlled environments allows for precise control over light quality and quantity, enabling the production of nutritionally enhanced sprouts and microgreens year-round.
Impact of Environmental and Priming Factors on Consumer Acceptance
The manipulation of environmental and priming factors to enhance the nutritional value of microscale vegetables must also consider consumer acceptance. Changes in environmental conditions, such as light quality or substrate type, can affect the sensory attributes of microscale vegetables, including their appearance, flavor, and texture. Therefore, it is important to strike a balance between maximizing nutritional content and maintaining consumer-acceptable sensory qualities. Further research is needed to explore the effects of different environmental and priming factors on the overall quality of microscale vegetables and their acceptance by consumers.
Market Trends and Consumer Demand for Sprouts and Microgreens
The market for sprouts and microgreens has seen significant growth in recent years, driven by increasing consumer interest in healthy eating, functional foods, and sustainable agricultural practices. These microscale vegetables are perceived as fresh, nutrient-dense, and versatile ingredients that can be easily incorporated into various dishes. As a result, they have gained popularity not only among health-conscious consumers but also within the culinary world, where they are used to enhance the flavor, texture, and visual appeal of meals.
Growth of the Microgreens Market
The global microgreens market has expanded rapidly, with more consumers seeking out these nutrient-rich vegetables for their health benefits. This growth is reflected in the increasing availability of microgreens in supermarkets, farmers' markets, and online platforms. Additionally, the rise of urban farming and indoor gardening has made it easier for consumers to grow their own microgreens at home, further fueling market demand. The microgreens market is expected to continue growing as awareness of their nutritional benefits spreads and as consumers increasingly prioritize healthy, plant-based foods in their diets.
Trends in Consumer Preferences
Consumer preferences for sprouts and microgreens are influenced by several factors, including taste, appearance, and perceived health benefits. Consumers tend to favor microgreens with vibrant colors, delicate textures, and mild flavors. Varieties such as arugula, broccoli, radish, and sunflower are particularly popular due to their distinctive flavors and high nutrient content. The trend toward organic and pesticide-free produce has also driven demand for microgreens grown using sustainable and environmentally friendly practices.
Challenges in the Microgreens Market
Despite the growing popularity of microgreens, the market faces several challenges. One of the main challenges is the short shelf life of microgreens, which can limit their availability and increase the risk of spoilage during transportation and storage. Additionally, the production of microgreens requires precise control over environmental conditions, which can be resource-intensive and costly. These factors may result in higher prices for microgreens compared to other vegetables, potentially limiting their accessibility to a broader consumer base.
Opportunities for Innovation and Growth
The microgreens market presents several opportunities for innovation and growth. Advances in controlled environment agriculture (CEA) technologies, such as vertical farming and hydroponics, offer the potential to scale up microgreens production while reducing resource use and environmental impact. Moreover, the development of new microgreens varieties with enhanced nutritional profiles, flavors, and sensory attributes could attract a wider range of consumers. Marketing strategies that emphasize the health benefits and culinary versatility of microgreens could also help to drive demand.
Future Outlook for the Sprouts and Microgreens Market
The future of the sprouts and microgreens market looks promising, with continued growth expected in response to rising consumer demand for healthy, functional foods. As the market evolves, producers may need to adopt innovative cultivation techniques, explore new marketing channels, and address challenges related to shelf life and production costs. The integration of technology in microgreens production, such as automation and artificial intelligence, could further enhance efficiency and sustainability, positioning microgreens as a key component of the future food system.
Conclusions
The growing interest in healthy eating and sustainable diets has driven the popularity of microscale vegetables, such as sprouts and microgreens, as novel functional foods. These microscale vegetables are nutrient-dense and rich in bioactive compounds, offering significant health benefits. They can contribute to addressing global malnutrition challenges, particularly in regions with limited access to fresh produce. The production of sprouts and microgreens is relatively resource-efficient, requiring minimal inputs and offering the potential for year-round cultivation, even in urban environments.
Brassica vegetables, in particular, have shown promise due to their high content of health-promoting phytochemicals, such as glucosinolates and polyphenols. However, other underutilized species, including landraces and wild relatives, also offer valuable opportunities to enhance the diversity and nutritional quality of microscale vegetables. The variations in nutritional value and phytochemical content according to plant growth stages highlight the importance of selecting the optimal harvest time to maximize the health benefits of these crops.
Environmental and priming factors, such as growth environment, substrate, and seed treatments, play a critical role in influencing the nutritional quality of microscale vegetables. Advances in controlled environment agriculture (CEA) and biofortification techniques offer exciting opportunities to enhance the nutritional content and functional properties of sprouts and microgreens. However, these innovations must be balanced with considerations of consumer acceptance, including sensory attributes such as flavor and appearance.
The market for sprouts and microgreens is poised for continued growth, driven by increasing consumer demand for healthy, nutrient-dense foods. Challenges related to production costs, shelf life, and market accessibility remain, but opportunities for innovation and growth abound. The integration of advanced cultivation technologies and the exploration of new microgreen varieties could further expand the market and enhance the role of microscale vegetables in promoting global nutrition security.
In conclusion, sprouts and microgreens represent a promising and versatile component of the human diet, offering both nutritional benefits and culinary appeal. As research continues to uncover the potential of these microscale vegetables, their role in healthy, sustainable diets is likely to expand, contributing to improved health outcomes and greater food security worldwide.
Acknowledgments
The author would like to thank the World Vegetable Center for supporting this research. Special thanks are also extended to the technical staff who assisted in the experiments and data collection.
References
Neufeld, L.M.; Hendriks, S.; Hugas, M.; Caroli, S.; Freire, W.B.; Lartey, A.; Briend, A. Healthy diet: A definition for the United Nations Food Systems Summit 2021. In UNSCN Nutrition; United Nations System Standing Committee on Nutrition: Geneva, Switzerland, 2021; pp. 1–6.
Neufeld, L.M.; Hendriks, S.; Hugas, M.; Caroli, S.; Freire, W.B.; Lartey, A.; Briend, A. Healthy diet: A definition for the United Nations Food Systems Summit 2021. UNSCN Nutr. 2021, 45, 1–6.
FAO; IFAD; UNICEF; WFP; WHO. The State of Food Security and Nutrition in the World 2020: Transforming Food Systems for Affordable Healthy Diets; FAO: Rome, Italy, 2020.
Global Panel on Agriculture and Food Systems for Nutrition. Future Food Systems: For People, Planet, and Prosperity; Global Panel on Agriculture and Food Systems for Nutrition: London, UK, 2020.
United Nations. The Sustainable Development Goals Report 2020; United Nations: New York, NY, USA, 2020.
WHO. Noncommunicable Diseases. Available online: https://www.who.int/news-room/fact-sheets/detail/noncommunicable-diseases (accessed on 15 January 2022).
WHO. Global Health Estimates: Leading Causes of Death. Available online: https://www.who.int/data/global-health-estimates (accessed on 15 January 2022).
Willett, W.; Rockström, J.; Loken, B.; Springmann, M.; Lang, T.; Vermeulen, S.; Garnett, T.; Tilman, D.; DeClerck, F.; Wood, A.; et al. Food in the Anthropocene: The EAT-Lancet Commission on healthy diets from sustainable food systems. Lancet 2019, 393, 447–492.
HLPE. Food Security and Nutrition: Building a Global Narrative towards 2030; FAO: Rome, Italy, 2020.
FAO; IFAD; UNICEF; WFP; WHO. The State of Food Security and Nutrition in the World 2021: Transforming Food Systems for Food Security, Improved Nutrition and Affordable Healthy Diets for All; FAO: Rome, Italy, 2021.
WHO. Increasing Fruit and Vegetable Consumption to Reduce the Risk of Noncommunicable Diseases; World Health Organization: Geneva, Switzerland, 2021.
Royal Society. Hidden Hunger and Malnutrition in the 21st Century; Royal Society: London, UK, 2020.
WHO. Diet, Nutrition and the Prevention of Chronic Diseases: Report of a Joint WHO/FAO Expert Consultation; WHO Technical Report Series 916; WHO: Geneva, Switzerland, 2003.
Oyebode, O.; Gordon-Dseagu, V.; Walker, A.; Mindell, J.S. Fruit and vegetable consumption and all-cause, cancer and CVD mortality: Analysis of Health Survey for England data. J. Epidemiol. Community Health 2014, 68, 856–862.
Khoury, C.K.; Achicanoy, H.A.; Bjorkman, A.D.; Navarro-Racines, C.; Guarino, L.; Flores-Palacios, X.; Engels, J.M.M.; Wiersema, J.H.; Dempewolf, H.; Ramírez-Villegas, J.; et al. Estimation of countries’ per capita fruit and vegetable supply compared with the recommended daily amount reveals remarkable inadequacies in global food production. PLoS ONE 2014, 9, e104059.
Miller, V.; Yusuf, S.; Chow, C.K.; Dehghan, M.; Corsi, D.J.; Lock, K.; Popkin, B.; Rangarajan, S.; Khatib, R.; Lear, S.A.; et al. Availability, affordability, and consumption of fruits and vegetables in 18 countries across income levels: Findings from the Prospective Urban Rural Epidemiology (PURE) study. Lancet Glob. Health 2016, 4, e695–e703.
Siegel, K.R.; Ali, M.K.; Srinivasiah, A.; Nugent, R.A.; Narayan, K.V. Do we produce enough fruits and vegetables to meet global health need? PLoS ONE 2014, 9, e104059.
Shetty, P. Nutrition transition and its health outcomes. Indian J. Pediatr. 2013, 80, S21–S27.
Patel, J.; Cudjoe, J.; Yu, A.; Waring, M.; Hunter-Adams, J.; Resnick, B.; Sivashanker, K.; Gunaratne, N. Expanding the supply of fresh fruits and vegetables to low-income families through policy change in the US. PLoS ONE 2016, 11, e0169089.
U.S. Department of Agriculture. The Food Access Research Atlas. Available online: https://www.ers.usda.gov/data-products/food-access-research-atlas/ (accessed on 18 January 2022).
Dabbene, F.; Gay, P.; Tortia, C. Modelling and analysis of fresh food supply chains. In Simulation Modelling Practice and Theory; Elsevier: Amsterdam, The Netherlands, 2014; Volume 45, pp. 32–49.
Ben-Arie, R.; Mahrer, Y.; Shilo, M.; Levi, A. Real-time optimization of energy use in an energy-efficient greenhouse using a simulation-based decision-support system. Biosyst. Eng. 2021, 202, 65–76.
Brennan, J.M.; Fagan, C.C.; Sexton, J.; Dobson, A.D.W.; Betts, N.M.; Fieldsend, A.; Tiwari, B.K. The use of alternative processing technologies for the extraction of phytochemicals from fruits and vegetables for incorporation into functional foods. In Functional Foods, Ageing and Degenerative Disease; CRC Press: Boca Raton, FL, USA, 2021; pp. 37–56.
Kholif, A.E.; Morsy, T.A.; Anele, U.Y.; Lopéz, S.; El-Sayed, A.M.; Azzaz, H.H. Enhancing the productive performance and milk composition of lactating goats fed halophytes and date palm by-products with or without exogenous enzymes in arid and semi-arid regions. Anim. Feed Sci. Technol. 2020, 264, 114489.
Yang, J.; Ou, S.; Meng, J.; Han, Q.; Zhang, H.; Ma, L.; Han, M. Evaluation of fruit and vegetable-based food consumption patterns in China. PLoS ONE 2017, 12, e0177019.
Fahey, J.W.; Zhang, Y.; Talalay, P. Broccoli sprouts: An exceptionally rich source of inducers of enzymes that protect against chemical carcinogens. Proc. Natl. Acad. Sci. USA 1997, 94, 10367–10372.
--
Ebert, A. W. (2022). Sprouts and microgreens—Novel food sources for healthy diets. Plants, 11(4), 571. https://doi.org/10.3390/plants11040571