Physiological Importance of riboflavin

Riboflavin, also called vitamin B-2, is one of several essential vitamins required as part of a balanced diet, as well as one of eight B-family vitamins.

Vitamin B2 is a water-soluble vitamin, so it dissolves in water. All vitamins are either water soluble or fat soluble.

Riboflavin is important for body growth. It helps in red blood cell production. It also aids in the release of energy from proteins.

Riboflavin is essential to the formation of two major coenzymes, flavin mononucleotide (FMN) and flavin adenine dinucleotide (FAD). Vitamin B-2 helps human body break down the three macronutrients -- protein, carbohydrate, and fat. Riboflavin, in the form of FAD, helps body break down fats and carbohydrates into fuel by contributing to the electron transport chain, a series of chemical reactions that give off usable energy for body cells.

Without an adequate amount of riboflavin, macronutrients like carbohydrates, fats, and proteins cannot be digested and maintain the body. With a healthy digestive system, the body can absorb most of the nutrients from the diet, so it is important to get most of the riboflavin from dietary sources.

Riboflavin also helps convert tryptophan to niacin, which activates vitamin B6. The conversion of vitamin B6 to the coenzyme pyridoxal 5'-phosphate requires FMN. Vitamin B-6 (pyridoxine) is important for normal brain development and for keeping the nervous system and immune system healthy.

Riboflavin (as FAD or FMN) is required for the metabolism of iron. It also plays an essential role in folate and related one-carbon metabolism, where FAD is required as a cofactor for methylenetetrahydrofolate reductase (MTHFR), a key folate-metabolizing enzyme.

Riboflavin also serves an antioxidant function due to its ability to activate antioxidant enzymes. Antioxidants protect body cells from damage caused by harmful chemicals called reactive oxygen species, or ROS.
Physiological Importance of riboflavin

Roles of vitamin A in human body

Vitamin A, a fat soluble nutrient has an important role in embryonic growth, vision and resistance to infection.

It is also involved in the regulation of various physiological functions such as gene expression, maintenance of immune system and red blood cell production.

Vitamin A is a generic term for all retinoids that qualitatively exhibit the biological activity of all-trans retinol. It has a clearly defined role in vision: when retinal tissue is deprived of vitamin A, rod and cone function is impaired.

It is also required for the integrity of epithelial cells throughout the body, via the regulatory action of retinoic acid at the level the gene.

A main dietary source of vitamin A are the carotenoids from fruits and vegetables. These carotenoids seem to have separate function as antioxidants in addition to their provitamin A function.

Active vitamin A is found only in animal sources. It is especially high in the fish liver oil from cod, halibut, salmon and shark. It is also found in beef and chicken liver and in eggs and dairy products.

Beta carotene, the vitamin A precursor, is found only in green and yellow orange fruits and vegetables, such as carrots, kale, kohlrabi, parsley, spinach turnip green and cantaloupe.

Vitamin A deficiency is rare in the US, but it is still a major public health problem in the developing world. It is most often associated with protein/calorie malnutrition and affects over 120 million children worldwide.

As early as 1500 BC, clinical symptoms of vitamin A deficiency such as night blindness were described by the Egyptians. Furthermore, the importance of vitamin A for resistance to infectious disease has been known for almost hundred years.

Extremely dry skin, dry hair, sloughing off of skin, and broken fingernails are other common signs of vitamin A deficiency. Vitamin A deficiency also decreases resistance to infections, and may contribute to the pneumonia associated with vitamin A deficiency.
Roles of vitamin A in human body