Role of the b-complex vitamins
Vitamins are essential to the human body. It plays a vital role in metabolism and maintains wellness. Vitamins should be maintained in minimum amount or else toxicity may develop. But when not consumed properly, deficiency diseases may also arise. Vitamins are further categorized as fat soluble (Vitamin A, D, E, and K) and water soluble (Vitamin B complex and Vitamin C). Vitamin B complex varies and each has exceptional role in the body, this group of nutrient works together in the body and may be found in the same food sources.
All acts as coenzyme and helps metabolize carbohydrate, protein and fats to provide energy and maintain proper tissue development. Studies show evidences of Vitamin B deficiency to be related in some diseases related to the nervous system. It also may prevent some problems related to aging, and has significant role in supporting the body’s immune system. It may be subcategorized as B1 (Thiamine), B2 (Riboflavin), B3 (Niacin), B6 (Pyridoxine), B12 (Cobalamin), Folic Acid, Biotin, Pantothenic Acid, Inositol, Choline, and PABA (Para-amino benzoic Acid).
Vitamin B1 or Thiamine is the first B complex to be recognized (Potter and Hotchkiss, 1998). Its main function is to serve as a coenzyme in metabolism of carbohydrate for energy and has role in nerve function with relation to actions of muscle. Daily intake of thiamine should be 1.0-1.5mg for adults, but may vary with age, sex and daily activities, (Potter and Hotchkiss, 1998). Main sources of this vitamin are liver, pork, egg yolk, whole and enriched grains, legumes, yeast, seeds and nuts. Deficiency may result to diseases of the nervous, gastrointestinal, muscular and cardiovascular system as well. Thiamine is destroyed by heat, specifically by cooking, but then, generally, we consume enough amount of thiamine.
Chronic alcohol users are susceptible of developing thiamine deficiency. Excessive intake of raw fish, which contains thiaminase; an enzyme destroying thiamine, also causes beriberi. The most common disease cause by thiamine deficiency is beriberi, affecting people of different ages and status throughout Asia for centuries. Its signs and symptoms are ataxia (severe muscle wasting and loss of coordination), pain, anorexia, mental disturbances and rapid heart beat. Wet beriberi affects cardiac function; it causes edema, an accumulation of fluid, making the myocardium weak and also the whole vascular system.
While dry beriberi mainly produces adverse effects in the nervous system. The patient may appear irritable, exhausted, anxious, and may report recurrent headaches. Wernicke-Korsakoff syndrome, a cerebral form of beriberi is a result of severe deficiency in thiamine, affecting the central nervous system, with the manifestations of severe ataxia, memory loss and confusion. The existing problem must be addressed by administering parenteral fluids containing Vitamin B complex.
Riboflavin (B2) has the same function as thiamine in our body. It is also essential for tissue repair and cellular growth that is why increase in riboflavin consumption is necessary during wound healing, pregnancy or lactation, and in growth period such as childhood. Major source of vitamin B2 is milk, and may also be found in some plant and animal food. Group of symptoms related with riboflavin deficiency is called ariboflavinosis: cheilosis; swelling of the lips and cracking in the corners of the mouth, glossitis; purplish-red discoloration and swelling of the tongue, and seborrheic dermatitis. 1.3 mg for men and 1.1 mg for women is the Recommended Dietary Allowance (Grodner, Long, Roth and de Young, 2004).
Niacin (B3), serves as coenzyme in several enzymes for energy metabolism. It has two forms, nicotinic acid and niacinamide. Food rich in protein are also the sources of niacin. Deficiency disorder is called pellagra, manifested by three D’s: diarrhea, altering proper digestion, absorption and excretion of food, resulting to glossitis, vomiting and weigth loss, dermatitis on skin portion that is exposed in the sun, and dementia, characterized by anxiety, insomnia, confusion, disorientation and psychosis. Before niacin was identified, patient who experience deficiency was sent to asylums, because of their psychological manifestations. When intake of niacin exceeds 35mg NE per day, (Grodner et al., 2004), it has cardiovascular effects resulting to flushing all throughout the body.
In order for the body to metabolize normally, it needs Pyridoxine (B6). There are three forms: pyridoxine, pyridoxal and pyridoxamine (Grodner et al., 2004). It acts as a coenzyme for protein and amino acid metabolism, and for fatty acid and carbohydrate as well. Good sources of B6 are chicken, fish, pork, liver, eggs, green vegetables, and grain cereals. To lower the neurologic side effects, patients under medication like isoniazid, cycloserine, hydralazine and penicillamine require vitamin B6 supplements. Usually, vitamin B6 deficiency coexist with minimum intake of other vitamin B.
Vitamin B12 or cobalamin is essential in fatty acid, amino acid and folate metabolism, and maintains myelin sheath. Intrinsic factor in the gastric mucosa is important for the absorption of vitamin B12, without B12 and intrinsic factor, malabsorption may occur. Patients undergone billroth surgery is at risk for deficiency and also the older person due to physiologic changes with regards to intrinsic factor production in the stomach lining. That is why these groups of people are advised to take up B12 supplements. Cobalamin deficit may damage the myelin sheath in the spinal cord. Megaloblastic and pernicious anemia arises from B12 deficiency and folate dysfunction.
Folate is a vitamin found in foods, while folic acid is a synthetic form. It also lays a role in amino acid metabolism, like the other vitamin B, and for the synthesis of DNA and RNA. Green leafy vegetables are rich in folate. But then, folate is sensitive to heat, so cooking diminishes the available amount of folate in the food. Many foods rich in ascorbic acid are also a good source of folate. Both men and women need 400 mcg of folate daily. But for nursing mothers, daily folate requirement increases to 500 mcg, and 600 mcg per day during pregnancy (Grodner et al., 2004). This is because folate is vital in formation of fetal neural tubes. If inadequate, it may result to neural tube defect, compromising the fetal brain and spinal cord development. Resulting serious congenital birth defects are spina bifida; bulging of the spinal cord outside the spinal column leaving it unprotected, resulting to paralysis and incontinence, and anencephaly, a congenital defect where the brain does not fully develop causing death shortly after birth.
Biotin, though only needed in very small amount, assists in carbon dioxide transfer from one compound to another, and also for metabolism of protein, fat and carbohydrate. It is produced in the lower intestinal tract by the normal flora. It is also found in many foods like liver, kidney, egg yolk, peanut butter and yeast. Deficiency in biotin results to alopecia or commonly known as hairloss, skin rash, glossitis, loss of appetite and apparently, weight loss. It has no known toxicity.
Panthothenic acid also functions as a coenzyme for fat, protein and carbohydrate metabolism. Daily intake should be 5 mg per day, and may be seen from foods rich in other vitamin B complex (Lieberman and Bruning, 2007). Inadequate intake may be associated with some signs of depression, less tolerance to stress and decreased resistance to infection. Daily intake greater than 10 grams may result to diarrhea.
Choline, on the other hand, is very important in the synthesis of a neurotransmitter called acetylcholine, and lecithin, a phospholipid. Human body has the ability to produce choline through methatione, an amino acid, however, this is not enough to meet the body requirement so food sources are still needed. Rich sources are peanut, milk, and eggs. Though deficiency is rare, toxicity may present as diaphoresis, hypotension, vomiting, reduced growth and liver damage. Upper Intake Level for adults is 3500 mg/day. Deficiency in this vitamin is unusual.
Grodner, M., Long, S. Sara Long Roth, Sandra DeYoung. (2004). Foundations and Clinical Applications of Nutrition: A Nursing Approach. Philadelphia: Elsevier – Health Sciences Division.
Lieberman, S. & Bruning, N. (2007). The Real Vitamin and Mineral Book: A Definitive Guide to Designing Your Personal Supplement Program. New York: Avery.
Potter, N. & Hotchkiss, J. (1998). Food Science. (5th Edn.). Gaithersburg, Maryland: Aspen Publishing, Inc.
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