Vegetables are rich source of many essential micronutrients, including vitamins A, C and K, folate, several minerals and dietary fiber. In addition, vegetables are rich in beneficial health promoting phytochemicals, such as antioxidants which play an important role in reducing the risks of many chronic diseases (Table 1). Vegetables provide a major dietary source for phytochemicals with potential anti-obesity property. Vegetable crops are efficient source of micronutrients.

Micronutrient malnutrition is a lack of essential vitamins (Vitamin A, B, and C) and minerals (Zn, Fe, Ca) required in small amounts by the body for proper growth and development. Even though micronutrients are needed in minute quantities (i.e., micrograms to milligrams per day), they have tremendous impact on human health and well being. Widespread malnutrition is largely a result of dietary inadequacy and unhealthy lifestyles. Globally about 805 million peoples are chronically undernourished. The vast majority of these undernourished people live in developing countries, where an estimated 791 million were chronically hungry (2012-14). Micronutrients deficiencies result in learning disabilities, reduced work capacity and serious illness. Vegetable biofortification is a sustainable and cost-effective strategy to address the malnutrition in developing countries is top most priority. Consuming nutrient dense vegetable is a first step along the road to overcoming malnutrition but it is necessary to recognize that issues of cost and local availability is crucial.

Carotenoids

Carotenoids are yellow, orange and red pigments in plants. Humans cannot synthesize carotenoids and therefore must rely on dietary sources to provide sufficient level for their daily requirement. Vitamin A is essential for vision, immune response, epithelial cell growth and repair, bone growth, reproduction and maintenance of the surface linings of the eyes. Vitamin A deficiency (VAD) is the leading cause of preventable blindness in children and increases the risk of disease and death from severe infections and causes night blindness and maternal mortality.

Lycopene is a carotenoid red colour pigment does not have pro-vitamin A activity but it is an excellent dietary antioxidant and it plays a major role in reducing the risk of a number of cancers and coronary heart disease. At least 85% of our dietary lycopene comes from fresh tomato fruit and tomato-based products (sauce, ketchup, paste juice).

The xanthophylls, lutein and zeaxanthin are the plant pigments that play a critical role in the prevention of age-related macular degeneration (AMD) which leads to blindness. Lutein and zeaxanthin are found in green, certain yellow/orange vegetables and squash. Green leafy vegetables are good sources of lutein, but poor sources of zeaxanthin. The main source of zeaxanthin is orange pepper.

Anthocyanins

These water-soluble flavonoid pigments are responsible for the red, purple, and blue colours found in many flowers, fruits, seeds, and vegetables. Anthocyanins are also valuable colour agents for food industry. They also offer protection against cardiovascular disease, certain cancer, and some other chronic diseases and have high antioxidant activity.

Betalains

Betalains are the yellow and violet pigments that substitute anthocyanins in plants. These pigments have strong antioxidant capacity and anti cancer activity. Beet root is the best source of red-violet betacyanins and the yellow-orange betaxanthins.

Glucosinolates (GLSs)

GLSs constitute a group of secondary plant metabolites in crucifer vegetables. The crucifer vegetables are good source of GLSs which reduces the incidence of certain cancers including bladder, colon, lung and breast in humans. Broccoli (both the sprouts and mature heads) are rich-sources of Glucoraphanin.

Polyphenols

Polyphenols are a class of phytochemicals that are likely candidates as anti-obesity agents. Polyphenols are abundant micronutrients in our diet, and evidence for their role in the prevention of degenerative diseases such as cancer and cardiovascular diseases is emerging.

Flavonols

Three flavonols quercetin, kaempferol and myricetin are mainly present in the vegetables. Particularly onions, hot peppers, kale, broccoli, rutabagas and spinach are good source of flavonols.

Flavones

Natural flavones consist of glycosides of luteolin and apigenin. Vegetable sources of flavones are from parsley and celery. Celery leaf is a main source of luteolin and apigenin in leaf stalk. Significant source of luteolin and apigenin present in globe artichoke.

Thiosulfinates

Onion, garlic, leek, welsh onion are rich in thiosulfides, which have been linked to reducing various chronic diseases.

Folate

Folates are a group of water-soluble B vitamins (B9). Humans cannot synthesize folates (vitamin B9) and thus have to rely on plant food supplying these essential vitamins. Folate deficiency can cause neural tube defects (NTDs, such as spina bifida and anencephaly) and megaloblastic anaemia and are associated with a higher risk on major depressive disorder Alzheimer disease cardiovascular and coronary diseases stroke and several cancers. Folate levels in vegetables are relatively high. Considering their consumption, vegetables represent a rich source of folates in the human diet. Folates contained in raw vegetables.

Table 1: Health promoting compounds present in vegetable crops

Compounds Source of vegetables Biological activity
1.Carotenoids
α - and β-carotenes Carrot, kale, pumpkin, spinach Provitamin A activity
Lycopene Tomato, watermelon Antioxidant and anticancer activity
Lutein Kale, spinach prevention of age-related macular degeneration (AMD)
Zeaxanthin Lettuce, parsley prevention of age-related macular degeneration (AMD)
2. Polyphenols
Anthocyanidins Red cabbage, purple cauliflower
Cyanidin Purple carrot, red onion Antioxidant and anticancer activity
Malvidin Rhubarb Reduction cardio vascular disease (CVD)
Nasunin Purple brinjal Antioxidant activity
Flavonols
Quercetin Yellow onion, broccoli, curly kale Anti-obesity activity
Myricetin Garlic, broccoli, cherry tomato Anti diabetic activity
Kaempferol Leek Antioxidant and anticancer activity
Flavones
Apigenin Celery, parsley Antioxidant and anticancer activity
Luteolin Capsicum Anti-obesity activity
Isoflavones Garden pea Anticancer and CVD activity
Phenolic acids
Chlorogenic acid Black carrot Anti-obesity activity
3. Glucosinolates
Glucoraphanin Green and purple broccoli, purple cauliflower, red cabbage Anticancer activity
Glucoiberin Cauliflower, cabbage, Brussels sprouts, kale, Purple cauliflower Anticancer activity
Sinigrin Cauliflower, cabbage, kale Brussels sprouts Anticancer activity
Glucoraphasatin Radish Prevention of Cholesterol gallstones
4. Sulphides/thiols
Methiin Onion Antibacterial and antifungal
Alliin Garlic Antibacterial and antifungal
5. Phenolic compounds
Chlorogenic acid Carrot (purple), potato, sweet potato, red leafed lettuce Antichronic activity anti-obesity
Betalains
Betacyanins Garden beet Antioxidant and anticancer activity
Betaxanthins Garden beet Antioxidant and anticancer activity
Folate Spinach, broccoli, Brussels sprout Anti neural tube defects (NTDs) and depression disorders
Vitamin C Green chilli, tomato, cauliflower, cabbage, turnip leaves, Brussels sprouts Prevention of scurvy


About Author / Additional Info:
Working as a Senior Scientist at ICAR-Indian Agricultural Research Institute, Pusa, New Delhi