Table 1 Different vitamins found in different functional foods and their beneficial properties outlined

Vitamin A

900 μg/day for men, 700 μg/day for women

Eggs, fish oil, fish liver, milk, corn, yam, sweet potato, carrot, lima bean, sorghum, green soybeans

Antioxidant, fat-soluble

Helps in antibody response (particularly IgA); develops type 1 and type 2 helper T cells; prevents cancer by protecting DNA from damage by free radicals; maintains epithelium of the cornea; acts as a precursor to visual pigments

[27,28,29]

Vitamin B6

1.3 mg/day for both men and women

Potato, white rice, chicken, beef, grains, legume, fish, non-citrus fruits, banana, onion, pineapple

The enzymatic cofactor, water-soluble, highly reactive during phosphorylation, confer some antioxidant properties

Involved in the maturation of lymphocytes; required for the synthesis of antibodies and cytokines; enhances immune response; could potentially reduce hypertension; required for the metabolism of amino acids, sugars, and fatty acids

[27, 30,31,32,33,34]

Vitamin B12

2.4 μg/day for both men and women

Beef, whole milk, egg, shellfish, turkey, mutton, soybean, tea drink, fish sauce, fermented fish, cheese

The enzymatic cofactor, water-soluble, may potentially confer antioxidant properties

Required for synthesis of antibodies and cytokines; involved in erythrocyte maturation; benefits cardiovascular system through the reduction in homocysteine; needed for healthy bones; increases the abundance of cytotoxic T cells

[27, 32, 33, 35, 36]

Folate

300–400 μg/day for both men and women

pasta, bean, green salad, orange juice, peanut, spinach, lentil, parsley, beets, romaine lettuce, Brussels sprouts

The enzymatic cofactor, water-soluble, reduced form has similar antioxidant property as Vitamin C and E

Regulates immune response by type 1 helper T cells; improves the cytotoxic function of NK cells; needed by regulatory T cells in the small intestine; methylates cytosine in DNA; produces purines and pyrimidines

[27, 32, 33, 35, 37,38,39]

Vitamin C

90 mg/day for men, 75 mg/day for women

Guava, oranges, lemon, broccoli, papaya, red bell pepper, pineapple, blackberry, black currant, strawberry, tomato

Enzymatic cofactor, water-soluble, antioxidant

Boosts collagen production; promotes differentiation of B and T lymphocytes; eliminates pathogens and assists in the production of antibodies; involved in vasodilation; protects DNA from oxidative damage

[27, 40,41,42,43]

Vitamin D

15 μg/day for both men and women

Egg yolk, tuna, mushroom, soy milk, cow milk, sardines, orange juice, salmon, eel, cod, butter

Antioxidant, Fat-soluble

Helps to stimulate an innate immune response; enhances antigen processing; supports differentiation of monocytes to macrophages; maintains calcium concentration in extracellular fluid; required for strong bones

[27, 33, 44]

Vitamin E

15 mg/day for both men and women

Sunflower seeds, asparagus, shrimp, avocado, olive oil, almond, raspberry, spinach, broccoli, bell peppers, carrot

Antioxidant, Fat-soluble

Increases IL-2 levels; protects the body from oxidative damage; metabolizes arachidonic acid; stabilizes lipid bilayer of cell membranes; regulates protein kinase C

[27, 33, 45, 46]