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REVIEW MULTIVITAMINS By Ronelle van der Merwe (B.Pharm) Amayeza Information Centre Information on vitamins Vitamins are organic substances that cannot be produced by the human body. The only way of getting all of the vitamins the body needs is to ingest them, in small quantities, through the diet. Vitamins are essential for normal cell function, growth and development. There are 13 essential vitamins, which the body needs to function. They can be divided into two groups, fatsoluble or water-soluble. Fat-soluble vitamins include vitamins A,D,E and K. The body stores small amounts of these for use as needed. The water-soluble vitamins are the B vitamins and vitamin C. These vitamins are easily absorbed by the body, which normally doesn't store large amounts. The kidneys remove excess water-soluble vitamins ingested, which are excreted in the urine. The recommended daily allowance (RDA) is the amount of each vitamin that the average person needs to remain healthy. A person who consumes too little or too much of a certain vitamin is at risk of developing a nutritional disorder. Although many of the vitamin deficiency diseases, such as rickets and scurvy, have been largely eliminated from developed countries, many western diets are poor in nutritional value. There is currently great debate around whether or not vitamin supplementation can prevent many of the diseases that plague western culture. Similarly, ingesting too much of a certain vitamin can have negative consequences for a person’s health. When taken in daily doses that are more than 10 times the recommended daily allowance, vitamins A and D are toxic but not vitamins E and K. Even though high doses of vitamins E and K may not be toxic, they may still cause unpleasant side effects, for example, nausea and headaches. High doses of the water-soluble vitamins, on the other hand, will simply be excreted from the body and supplementation in excess of the RDA would simply be a waste. Only two of the fat-soluble vitamins (A and E) are stored in the body to any extent. Depending on the body’s requirements, vitamin C is stored in the smallest amounts and vitamin B12 in the largest amounts. It is estimated that it would require about seven years to deplete the body’s reserves of vitamin B12. Ensuring an adequate vitamin intake To ensure sufficient vitamin intake it is important to consume a variety of nutrient-dense foods and beverages within the basic food groups. At the same time, choose foods that limit the intake of saturated and trans-fats, cholesterol, added sugars, salt and alcohol. Ideally, vitamins should be obtained in sufficient quantities from the diet. Vitamin needs should be met primarily through consuming foods, with supplementation suggested for certain sensitive populations, such as: People with certain health problems (e.g. people who are chronically ill, alcoholics) People following a vegetarian or vegan diet Women who are pregnant or breastfeeding Whole foods are the best source of vitamins and minerals. Some of the benefits they offer over vitamin supplements are; Greater nutrition. Whole foods usually contain a variety of the micronutrients the body needs. An orange, for example, provides vitamin C but also beta carotene, calcium and other nutrients. Essential fibre. Whole foods provide the essential fibre the body needs for effective digestion. It may even help prevent certain diseases, for example diabetes and heart disease. Protective substances. Whole foods also contain other substances recognised as essential for good health. Fruits and vegetables, for example, contain phytochemicals. These are naturally occurring food substances that may help protect against certain diseases for example cancer, diabetes and heart disease. Whole foods are also sources of antioxidants – substances that slow down oxidation – a natural process that leads to cell and tissue damage. Table 1. Sources, needs and RDA’s of fat- and water-soluble vitamins Vitamin Principal source Fat-soluble vitamins Vitamin A Liver, whole milk, fortified dairy products, eggs, carrots, dark leafy vegetables, dark yellow squashes, sweet potato, pumpkin Vitamin D Vitamin E Vitamin K Fortified dairy products, egg yolks Vegetable oil, margarine, wheat germ, nuts, green leafy vegetables, sunflower seeds Green leafy vegetables, broccoli, brussels sprouts, cabbage, lettuce, soybean oil, canola oil Water-soluble vitamins Vitamin B1 Enriched, fortified (Thiamine) or whole-grain products, brewer's yeast, organ meats, pork, legumes, seeds, nuts Vitamin B2 Organ meats, dairy (Riboflavin) products, enriched or fortified grain products Niacin (Nicotinic acid) Vitamin B6 (Pyridoxine) Principal importance Effects of deficiency Effects of excess RDA (SA recomme adults) 1000 mic Normal vision Healthy skin and other surface tissues Defence against infections Absorption of calcium and phosphorus from the intestine Bone mineralisation Growth and repair Antioxidant Animal protein, enriched, fortified or whole-grain products Chicken, fish, pork, kidney, liver, bran, potatoes and other starchy vegetables, Formation of blood clotting factors Normal blood clotting Night blindness Thickening of skin around hair follicles Drying of the whites of the eyes and cornea Blindness Spots on the whites of the eyes Risk of infection Death Abnormal bone growth and repair Rickets in children Osteomalacia in adults Muscle spasms Rupture of red blood cells Nerve damage Bleeding Headache Peeling of the skin Enlargement of the spleen and kidneys Bone thickening Joint pains Poor appetite Nausea Vomiting Increased urination Weakness Nervousness Thirst Skin itching Kidney failure Calcium deposits throughout the body Increase in vitamin K requirement 5 microg 10 micro 65 micro Carbohydrate metabolism Nerve and heart function Beriberi in infants and adults, with heart failure and abnormal nerve and brain function 1,4 mg Carbohydrate metabolism Healthy mucous membranes Fissures and scaling of the lips and corners of the mouth Dermatitis Pellagra 1,6 mg Chemical reactions in cells Carbohydrate metabolism Amino acid and fatty acid metabolism Nervous system function Convulsions in infants Anaemias Nerve and skin 18 mg 2 mg non-citrus fruits, disorders Healthy skin highly fortified cereals Biotin Kidney, liver, milk, Carbohydrate and Inflammation of the egg yolk, fresh fatty acid skin and lips vegetables, rolled metabolism oats Vitamin B12 Animal and dairy Maturation of red Anaemias (Cobalamin) products, liver, blood cells Some psychiatric beef, shellfish, Nerve function disorders fortified ready-to DNA synthesis Poor vision eat cereals Folic acid Liver, yeast, Maturation of red Decrease in number legumes, green leafy blood cells, and type of blood vegetables, orange cells DNA and RNA juice, fortified synthesis ready-to-eat cereals, pasta, flour, bread Pantothenic acid Animal products, Carbohydrate and fat Neurologic disease whole-grain cereals, metabolism Burning feet legumes Vitamin C Green and red Bone and connective Scurvy (bleeding peppers, broccoli, tissue growth loose teeth, spinach, tomatoes, inflammation of the Wound repair potatoes, gums) Function of blood strawberries, citrus vessels fruit, guavas Antioxidants 1. RE = Retinol Equivalent 2. One RE = 1 microgram of retinol = 3.33 IU of vitamin A activity = 6 micrograms of beta-carotene. 3. Vitamin D is expressed as cholecalciferol. One microgram of cholecalciferol = 40 IU of vitamin D. 4. Alpha-TE = alpha-tocopherol equivalent. 5. One alpha –TE = 1 mg of d-alpha-tocopherol=1.49 IU of vitamin E activity. 1 IU=1 mg of dl-alpha-tocopheryl acetate. In summary Vitamins are important for the normal functioning of the body. The best source of vitamins is a balanced diet. It is important to remember that multivitamin supplements are not a substitute for a healthy diet. Where vitamin supplementation is concerned it is simply not a case of “if some is good, a lot is better.” High doses of certain vitamins can be toxic. The best way to get all of the vitamins and other nutrients the body needs is through ingesting a variety of nutrient dense foods and beverages. References 1. Up to Date. Version 15.3, 2008. 2. Micromedex Healthcare Series. 2007. Thomson Micromedex, Greenwood Village, Colorado. 3. http://www.fda.gov/consumer/updates/vitamins 4. http://www.mayoclinic.com/print/supplements 5. http://www.hsph.harvard.edu/nutritionsource/what-should-you-eat/vitamins 6. Berkow R. The Merck Manual of Medical Information. Home Edition. 1997. USA: Merck & Co, Inc. 100 micr 1 microg 200 micr 6 microg 60mg