*14.2.2 Function*

Vitamin B-complex has several health benefits:

Thiamin/thiamine (B1) is used for the treatment of Alzheimer's disease [110], congestive heart failure [111], and cancer [112].

Riboflavin (vitamin B2) is used to prevent cataracts [113] and migraine headaches [114].

Niacin (B3) is used to prevent insulin-dependent diabetes mellitus [115]. It has a significant role to treat high cholesterol and cardiovascular disease [116].

Pantothenic acid (B5) can help in wound healing [117] and play an important role to maintain cholesterol levels [118].

Vitamin B6 has a vital role to prevent cardiovascular disease [119], kidney stones, and immune and cognitive functions [120]. It is also used for the treatment *Sources and Health Benefits of Functional Food Components DOI: http://dx.doi.org/10.5772/intechopen.104091*

of premenstrual syndrome [121]. Vitamin B6 can protect from side effects of oral contraceptives, nausea, and vomiting in pregnancy [122] and reduce depression.

Biotin (B7) is used for the treatment of diabetes [123] and in the prevention of some birth defects [124]. It plays a vital role in the treatment of cholesterol [125], brittle fingernails [126], seborrheic dermatitis [127], and hair loss.

Folic acid (B9) is used to prevent some pregnancy complications, such as fetal neural tube defects [128]. It may be used to prevent certain heart defects and limb malformations [129] and birth defects [130]. Folic acid is used to prevent colorectal and breast cancer [131], heart diseases [132], Alzheimer's disease, and cognitive impairment [133].

Vitamin B12 plays an important role in the prevention of neural tube defects, cancer [134], cardiovascular disease [135], depression, Alzheimer's disease, and dementia [136].

#### **14.3 Vitamin C**

Vitamin C (ascorbic acid) is a very effective nutrient and the main sources of vitamin C are citrus fruit (oranges and orange juice), strawberries, peppers, broccoli, blackcurrants, brussels sprouts, and potatoes. It plays an important role against immune system deficiencies, cardiovascular disease [137], prenatal health problems, eye disease, and skin wrinkling. Vitamin C works as an antioxidant and can prevent scurvy, lead toxicity, and cancer [138].

#### **14.4 Vitamin D**

Vitamin D is a combination of calciferol (*vitamin D*2) and cholecalciferol (*vitamin D*3). Vital sources of vitamin D are liver, egg yolks, red meat, fortified foods (e.g. fat spreads and breakfast cereals), and oily fish (sardines, salmon, herring, and mackerel). Several functions of vitamin D exist in the human body. Vitamin D promotes healthy bones and teeth, supports immune, brain and nervous health, and manages diabetes by regulating insulin levels. It has also a beneficial role in lung function and cardiovascular health and influences the expression of genes involved in cancer development.

#### **14.5 Vitamin E**

Vitamin E has several forms and the human body can use only alpha-tocopherol form. Good sources of vitamin E are plant-based oil (e.g. sunflower, soya, corn, and olive oil), nuts, seeds, fruits, and vegetables. The potential health benefits are moisturizing skin, wound healing, preventing cancer [139], reducing skin itching and eczema, psoriasis, preventing and minimizing the appearance of scars, uses for treatment of wrinkles, preventing sunburn, promoting nail health and enhance immune response [140]. Vitamin E is also used for the treatment of diabetes and dementia [141].

#### **14.6 Vitamin K**

Vitamin K is a group of compounds and of them, the main are vitamin K1 and vitamin K2. The main sources of vitamin K1 are leafy greens vegetables and other vegetables (brussels sprouts, broccoli, cauliflower, and cabbage). However, sources of vitamin K2 are meats, fish, liver, cheeses, and eggs. Vitamin K plays an important role to prevent osteoporosis [142], vascular calcification [143], and cardiovascular disease. Besides these, it has other health benefit roles, such as bone health, cognitive health, and heart health.
