Vitamins, Water-Soluble

Nutrition and Well-Being A to Z, 1st ed., (2004) by Kiran B. Misra

Vitamins, Water-Soluble

Vitamins are essential organic substances that are needed in small amounts in the diet for the normal function, growth, and maintenance of body tissues. Water-soluble vitamins consist of the B vitamins and vitamin C. With exception of vitamin B 6 and B 12 , they are readily excreted in urine without appreciable storage, so frequent consumption becomes necessary. They are generally nontoxic when present in excess of needs, although symptoms may be reported in people taking megadoses of niacin , vitamin C, or pyridoxine (vitamin B 6 ). All the B vitamins function as coenzymes or cofactors, assisting in the activity of important enzymes and allowing energy-producing reactions to proceed normally. As a result, any lack of water-soluble vitamins mostly affects growing or rapidly metabolizing tissues such as skin, blood, the digestive tract, and the nervous system . Water-soluble vitamins are easily lost with overcooking.

Thiamin (Vitamin B 1 )

Thiamin functions as the coenzyme thiamin pyrophosphate (TPP) in the metabolism of carbohydrate and in conduction of nerve impulses. Thiamin deficiency causes beri-beri, which is frequently seen in parts of the world where polished (white) rice or unenriched white flour are predominantly eaten. There are three basic expressions of beriberi: childhood, wet, and dry. Childhood beriberi stunts growth in infants and children. Wet beriberi is the classic form, with swelling due to fluid retention ( edema ) in the lower limbs that spreads to the upper body, affecting the heart and leading to heart failure. Dry beriberi affects peripheral nerves, initially causing tingling or burning sensations in the lower limbs and progressing to nerve degeneration, muscle wasting , and weight loss. Thiamine-deficiency disease in North America commonly occurs in people with heavy alcohol consumption and is called Wernicke-Korsakoff syndrome. It is caused by poor food intake and by decreased absorption and increased excretion caused by alcohol consumption.

Riboflavin (Vitamin B 2 )

Riboflavin is stable when heated in ordinary cooking, unless the food is exposed to ultraviolet radiation (sunlight). To prevent riboflavin breakdown, riboflavin-rich foods such as milk, milk products, and cereals are packaged in opaque containers. Riboflavin is a component of two coenzymes—flavin mononucleotide (FMN) and flavin adenine dinucleotide (FAD)—that act as hydrogen carriers when carbohydrates and fats are used to produce energy. It is helpful in maintaining good vision and healthy hair, skin and nails, and it is necessary for normal cell growth.

Riboflavin deficiency causes a condition known as ariboflavinosis, which is marked by cheilosis (cracks at the corners of the mouth), oily scaling of the skin, and a red, sore tongue. In addition, cataracts may occur more frequently with riboflavin deficiency. A deficiency of this nutrient is usually a part of multinutrient deficiency and does not occur in isolation. In North America, it is mostly observed in alcoholics, elderly persons with low income or depression , and people with poor eating habits, particularly those who consume highly refined and fast foods and those who do not consume milk and milk products.

Unlike fat-soluble vitamins, water-soluble vitamins are easily lost during cooking and processing. The body does not store excess quantities of most water-soluble vitamins, so foods bearing them must be consumed frequently. [Photograph by LWA-Stephen Welstead. Corbis. Reproduced by permission.]

Niacin (Vitamin B 3 )

Niacin exists in two forms, nicotinic acid and nicotinamide. Both forms are readily absorbed from the stomach and the small intestine. Niacin is stored in small amounts in the liver and transported to tissues, where it is converted to coenzyme forms. Any excess is excreted in urine. Niacin is one of the most stable of the B vitamins. It is resistant to heat and light, and to both acid and alkali environments. The human body is capable of converting the amino acid tryptophan to niacin when needed. However, when both tryptophan and niacin are deficient, tryptophan is used for protein synthesis.

WATER SOLUBLE VITAMINS

Vitamin Deficiency Recommended daily intake Food sources Toxicity Thiamine Vitamin B 1 ) Beri Beri: anorexia, weight loss, weakness, peripheral neuropathy Wernicke-Korsakoff syndrome: staggered gait, cross eyes, dementia, disorientation, memory loss Infants: 0.2 – 0.3 mg Children: 0.5 – 0.6 mg Adolescents: 0.9 – 1.2 mg Men: 1.2 mg Women: 1.1 mg Pregnant/Lactating Women: 1.4 mg Pork/pork products, beef, liver, yeast/baked products, enriched and whole grain cereals, nuts, and seeds None reported Riboflavin Ariboflavinosis: inflammation of tongue (glossitis), cracks at corners of mouth (cheilosis), dermatitis, growth retardation, conjunctivitis, nerve damage Infants: 0.3 – 0.4 mg Children: 0.5 – 0.6 mg Adolescents: 0.9 – 1.3 mg Men: 1.3 mg Women: 1.1 mg Pregnant Women: 1.4 mg Lactating Women: 1.6 mg Milk, eggs, mushrooms, whole grains, enriched grains, green leafy vegetables, yeast, liver, and oily fish None reported Niacin Pellagra: diarrhea, dematitis, dementia, and death Infants: 2 – 4 mg NE Children: 6 – 8 mg NE Adolescents: 12 – 16 mg NE Men: 16 mg NE Women: 14 mg NE Pregnant Women: 18 mg NE Lactating Women: 17 mg NE Meat, poultry, fish, yeast, enriched and whole grain breads and cereals, peanuts, mushrooms, milk, and eggs (tryptophan) Flushing of skin, itching, nausea & vomiting, and liver damage occurs at intake over 35 mg/day from supplements Pantothenic acid (Vitamin B 5 ) Rare Infants: 1.7 – 1.8 mg Children: 2 – 3 mg Adolescents: 4 – 5 mg Men & Women: 5 mg Pregnant Women: 6 mg Lactating Women: 7 mg Widely distributed in foods None reported Biotin (Vitamin B 8 ) Infants: Dermatitis, convulsions, hair loss (alopecia), neurological disorders, impaired growth Infants: 5 – 6 μg Children: 8 – 12 μg Adolescents: 20 – 25 μg Men & Women: 30 μg Pregnant Women: 30 μg Lactating Women: 35 μg Whole grains, eggs, nuts and seeds, widely distributed in small amounts Not known Vitamin B 6 Dermatitis, anemia, convulsion, depression, confusion, decline in immune function Infants: 0.1 – 0.3 mg Children: 0.5 – 0.6 mg Adolescents: 1.0 -1.3 mg Men & Women (19 – 50 years): 1.3 mg Men over 50 years: 1.4 mg Women over 50 years: 1.3 mg Pregnant Women: 1.9 mg Lactating Women: 1.2 mg Meat, fish, poultry, spinach, potatoes, bananas, avocados, sunflower seeds None from foods, excess intake above 100 mg/day from supplements causes neuropathy (nerve destruction) and skin lesions Folate Megaoblastic (macrocytic) anemia, abdominal pain, diarrhea, birth defects Infants: 65 – 80 μg Children: 150 – 200μg Adolescents: 300 – 400 μg Men & Women: 400 μg/day Pregnant Women: 600 μg Lactating Women: 500 μg Ready-to-eat breakfast cereals, enriched grain products, green vegetables, liver, legumes, oranges. The use of fortified foods are encouraged for all women of child bearing age (15-45 years). None (up to 5 mg/day); intake from fortified food and supplements over 1000 μg/day, not including food; folate masks vitamin B 12 deficiency allowing progression of neurological damage. Supplements containing >400 μg available by prescription only.