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Vitamins, Minerals and Supplements: Part Two

Posted on: Friday, 21 October 2005, 03:00 CDT

By Thompson, June

DIETARY SUPPLEMENTS

Vitamins and minerals are organic food substances found only in plants and animals and are essential to the normal functioning of the body. Although only required in small amounts, as previously discussed1 in the past decade there has been an increased use of vitamin, mineral, herbal and nutritional supplements in the general population. While deficiencies in such nutrients can be harmful to health, conflicting claims have been made about the health benefits of such supplementation. In the second of an occasional series on vitamins, minerals, and supplements, JUNE THOMPSON gives an overview of the role that water-soluble vitamins play in the health of the individual, including their functions, and the potential impact of any deficiency of these

Community practitioner 2005; 78, 10: 366-368

Water-soluble vitamins

Vitamins are micronutrients needed for normal body metabolism. They cannot be synthesised by humans and thus must be ingested in the diet.

There are two types of vitamins: fat-soluble and water-soluble. Fatsoluble vitamins are stored in the body, primarily the liver, and include vitamins A, D, E and K. (see part one).1

Water-soluble vitamins which include the B vitamins and vitamin C are not stored by the body and need on-going replacement, as discussed below.

Reference Nutrient Intake (RNI)

Dietary Reference Values (DRVs) for energy and nutrients were most recently set for the UK in 1991.2 They define the range of estimated dietary requirements in different groups of individuals. DRVs include the Reference Nutrient Intake (RNI) - the amount of a nutrient that is enough for almost every individual, even someone who has high needs for the nutrient in the distribution of individual requirements. The RNI for the B vitamins will be included in this update.

The B vitamins

These are an interrelated group of nutrients that occur together in foods and are known as the B-complex. They consist of thiamin (B1), riboflavin (B2), niacin (B3) pantothenic acid (B5), pyridoxine (B6), cobalamin (B12), biotin and folic acid (folate).

Light micrograph of thiamin crystals: Thiamin is essential for the metabolism of carbohydrates and for normal functioning of the nervous system, muscles and heart

Thiamin (vitamin B1)

Thiamin is essential for the metabolism of carbohydrates (to release energy) and for normal functioning of the nervous system, muscles and heart. The amount required is related to the amount of carbohydrate eaten.

Sources

Foods providing rich sources of thiamin include unrefined grain products, meat, especially pork, vegetables, dairy products, peanuts, legumes, fruits and eggs. In the UK there is mandatory fortification of white and brown flour with thiamin, to a level of not less than 0.24mg/100g flour, to replace losses during production; thus, cereal products are also a rich source of thiamin.'

Reference Nutrients Intake

Body stores of thiamin are limited and a regular intake is necessary. Thiamin requirement is related to energy consumption. The Reference Nutrient Intakes (RNIs), for adults and children are:

Children: Under 1 year 0.4mg/ 1000 kcal and 0.3mg/1000 kcal in infants.

Adult: 1.4 and 1mg/day for adult males and females respectively. In pregnancy and lactation, thiamin requirement increases to approximately 1.6-1.8mg/day.

There is consistent evidence that a significant minority of industrialised populations consume diets that offer marginal amounts of thiamin.4

Deficiency symptons

Symptoms of sub-clinical deficiency may be vague and include headache, tiredness, anorexia and muscle wasting, depression, constipation, heart and gastrointestinal problems. A regular daily thiamin intake of below 0.2mg/1000 kcal results in clinical deficiency and the disease known as beriberi, which affects the cardiovascular and nervous systems.5

Recently, two Israeli infants who were exclusively fed a soya formula made in Germany that lacked vitamin B, (thiamin) died from encephalopathy and other children were treated for serious neurological damage.5

In developed countries, most cases of thiamin deficiency however, are associated with chronic alcoholism where dietary intake of the vitamin may be low and absorption and utilisation impaired.

Thiamin deficiency may also be involved in foetal alcohol syndrome, characterised by growth retardation, psychomotor abnormalities and congenital malformations in the offspring of alcoholic mothers.3

The activity of (B,) thiamindependent enzymes is decreased in the brains of patients with Alzheimer's disease.6

Thiamin is destroyed by: high temperatures, alcohol and coffee. Excess is excreted in the urine.

Riboflavin (Vitamin B2)

Riboflavin promotes normal growth and assists in the synthesis of steroids, red blood cells, and glycogen, and helps to maintain the integrity of mucous membranes, skin, eyes and the nervous system. It supports the activity of antioxiclants and is involved in the production of adrenaline by the adrenal glands.' It is thought that riboflavin also aids the body in absorbing iron, since it is common for iron deficiency to accompany a deficiency in riboflavin.3,7

Free riboflavin is transformed in the liver to form the essential coenzymes, known as flavoproteins which are required to release energy from protein, carbohydrate and fat. The absorption of iron, zinc and calcium is impaired in riboflavin deficiency.3,7

Sources

The major sources of riboflavin are milk, eggs, enriched cereals and grain, ice cream, liver, some lean meats and green vegetables. Because riboflavin is degraded by light, loss will occur if foods are left out in sunlight, or any UV light.

Riboflavin is stable when heated but will leach into cooking water. The pasteurisation process causes milk to lose about 20% of its riboflavin content. Alkalis, such as baking soda, also destroy riboflavin. Riboflavin is a permitted colouring agent in foods and pharmaceuticals.3

Pellagra is the classic syndrome of niacin deficiency... the most common symptoms include a skin rash in sunexposed areas, dizziness, vomiting, constipation or chronic diarrhoea, and inflammation of the tongue and gastric mucosa

Reference Nutrient Intake

1.1mg/day for women and 1.3mg/ day for men.3 Riboflavin dietary allowances are 7 % higher in pregnancy because of increased maternal and foetal tissue synthesis and a small increase in energy utilisation.8

Deficiency symptoms

Riboflavin deficiency may occur as a result of inadequate nutrition, or cooking losses3,8 or intestinal malabsorption.' It can occur during pregnancy as a result of extra demand by the foetus,8 and may arise in neonates during phototherapy for jaundice.3

Other groups prone to riboflavin deficiency include older people with poor diet, chronic 'dieters', patients taking tranquillisers, persons who use fibre-based laxatives regularly, patients with hypothyroidism and women who exercise excessively.3

Riboflavin may occasionally be deficient before six months of age in some fully breastfed infants.9

Deficiency signs and symptoms include dry and cracked skin, sensitivity to bright light, itching, dizziness, insomnia, slow learning, weakness, sore throat, hyperaemia and oedema of the pharyngeal and oral mucous membranes, cheilosis, angular stomatitis, glossitis, seborrhoeic dermatitis, corneal vascularisation and anaemia.3

Riboflavin deficiency has also been associated with the development of cataracts and of rheumatoid arthritis3 and affects the immune response by decreasing antibody responses, thymic weight, and circulating lymphocyte numbers.8 Excess riboflavin is excreted in the urine.

Niacin (vitamin B^sub 3^)

Niacin or B^sub 3^ is the generic term for nicotinic acid and nicotinamide and is essential in the production of energy as it is the functional factor of two important coenzymes, (NAD - nicotine adenine dinucleotide and NADP - nicotine adenine dinucleotide phosphate).' These are responsible for the metabolism of carbohydrates, fats, and many other substances in the body.

It has been found that a high intake of niacin, particularly from food sources, may reduce the risk of Alzheimer's disease and agerelated cognitive decline.10

High dose treatment in (gram amounts) with niacin is also used to reduce fatty substances in the blood and has been shown to reduce plasma cholesterol levels (by an average of 20 to 35%).3,11

Nicotinic acid can be formed in humans from the metabolism of dietary tryptophan (an essential amino acid) and so niacin is not really a vitamin providing adequate tryptophan is available.3

Sources

Important sources of preformed niacin include beef, pork, wheat flour, maize (corn) flour, eggs and cow's milk. Human milk contains a higher concentration of niacin than cow's milk.3

In the UK there is mandatory fortification of flour (except wholemeal and certain other specified types) with nicotinic acid at a level of not less than 1.6mg/ 100g flour.3 Niacin is also present in the diet as a derivative of tryptophan.11

Reference Nutrient Intake

The UK RNI for niacin is 6.6mg niacin equivalent/1000 kcal, equivalent to 17 and 13mg/day in adult males and females respectively. An increment of 2.3mg/day niacin is recommended for lactating women.3

Deficiency sysmptons

Pellagra is the classic syndrome of niacin deficiency and is prevalent in societies where dietary animal protein is scarce or, rarely, in chronic alcoholic patients.11

The most common symptoms include a skin rash in sun-exposed areas, dizziness, vomiting\, constipation or chronic diarrhoea, and inflammation of the tongue and gastric mucosa. The neurological symptoms can include fatigue, sleeplessness, depression, memory loss, dementia and visual impairment.2,11

Pantothenic acid (vitamin^sub 5^)

Pantothenic comes from the Greek word pantos for everywhere, since it is literally in all foods.

Pantothenic acid is part of a component of coenzyme A (CoA) and as the acyl carrier protein (ACP), which are essential in the metabolism of carbohydrate, fat and protein.5

Pantothenic acid also aids in the utilisation of vitamins; improves the body's resistance to stress; helps in cell building and the development of the central nervous system; helps the adrenal glands; and fights infections by building antibodies.

It has been claimed that supplementation with pharmacological doses of pantothenic acid may alleviate the symptoms of rheumatoid arthritis and lupus erythematosus.3

Sources

The majority of pantothenic acid within foods is present as CoA. Chicken, beef, potatoes, oat cereals, tomato products, liver, kidney, yeast, egg yolk, broccoli and whole grains are reported to be major sources of the vitamin, while very high levels are present in royal bee jelly and in the ovaries of tuna and cod.

Cooking is reported to destroy 15-50% of pantothenic acid in meats and 37-78% of pantothenic acid is lost from vegetables during processing.

Breakfast cereals may be fortified with 5-6mg pantothenic acid/ 100g.3 Pantothenic acid derivatives sold as supplements or medicines are prepared synthetically as calcium pantothenate or panthenol.

In the UK, dietary supplements generally contain up to 550mg pantothenic acid; licensed medicines may contain a maximum of 50mg/ day pantothenic acid.3

Reference Nutrient Intake

Dietary reference values for pantothenic acid have not been established in the UK as it is considered to be adequately provided by the diet and deficiency in humans is extremely rare.3

Deficiency symptoms

Signs and symptoms exhibited by induced deficiency of pantothenic acid (not all of which were necessarily due to the deficiency) included irritability and restlessness, fatigue, apathy, malaise, sleep disturbance, gastrointestinal complaints (such as nausea, vomiting and abdominal cramps) neurological and other clinical effects such as numbness, paraesthesia, muscle cramps and staggering gait, hypoglycaemia and an increased sensitivity to insulin.'

Historically, pantothenic acid deficiency has been implicated in the 'burning feet' syndrome experienced by severely malnourished prisoners of war.3,12

The remaining B complex vitamins - B^sub 6^ (pyridoxine), B12 (cobalamin), biotin and folic acid (folate) will be covered in part three of this series.

Thiamin deficiency and effect on mood

The effects of nutrients on mood will be discussed more fully later, but thiamin deficiency may also have a significant effect on mood. Studies have found that deprivation may result in increased irritability and depression and an improvement in mood has been reported following the taking of a relatively small dose of thiamin (2mg) in subjects not thiamin deficient, as usually defined.4 Another study found the taking of I Omg of thiamin, for six weeks, was associated with greater feelings of well-being, and less fatigue, in a group of elderly Irish females living in the community with poor or marginal thymus status.4

Vitamins and minerals are organic food substances found only in plants and animals and are essential to the normal functioning of the body

References

1 Thompson J. Vitamins, minerals and supplements. Community Practitioner 2005; 78, 1:24-26.

2 Department of Health. Report on Health Social Subjects 4L Dietary Reference Values for Food Energy and Nutrients for the United Kingdom. Report of the Panel on Dietary Reference Values of the Committee on Medical Aspects of Food Policy. London: HMSO, 1991.

3 The Food Standards Agency. Safe upper levels for vitamins and minerals: report of the expert group on vitamins and minerals. London: Food Standards Agency, May 2003.

4 Benton D, Donohoe R. The effects of nutrients on mood. Public Health Nutrition 2000; 2: 3, 403-409.

5 Siegel-Itzkovich J. Babies fed defective formula are still being treated for neurological damage. British Medical journal 2004; 329: 1128.

6 Sierpina VS et al. Complementary and integrative approaches to dementia. Southern Medical Journal 2W5; 98: 6, 636-645.

7 Fishman SM et al. The role of vitamins in the prevention and control of anaemia. Public Health Nutrition 2000; 3: 2, 125-150.

8 Ladipo OA. Nutrition in pregnancy: mineral and vitamin supplements. American Journal of Clinical Nutrition 2000; 72: 1, 280s-290s.

9 Foote KD, Marriott LD. Weaning of infants. Archives of Disease in Childhood2003; 88: 488-492.

10 Morris MC et al. Dietary niacin and the risk of incident Alzheimer's disease and of cognitive decline. Journal of Neurology Neurosurgcry and Psychiatry 2004; 75: 1093-1099.

11 Halsted CH. Absorption of watersoluble vitamins [Small intestine] Current Opinion in Gastroenterology 2003; 19:2, 113-117.

12 Plesofsky-Vig N. Pantothenic acid. In: Shils M (ed). Nutrition in Health and Disease. 9th ed. Baltimore: Williams & Wilkins, 1999,423-432.

June Thompson

Part time health visitor and freelance journalist

Copyright TG Scott & Son Ltd. Oct 2005

Source: Community Practitioner

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