http://www.consumerlab.com/Multivitamins/multiminerals are among those supplements most likely to have quality problems. They contain multiple ingredients and, therefore, more possibility for error. Earlier tests by ConsumerLab.com have found multis that were short on ingredients, failed to dissolve properly, or were contaminated with heavy metals.
Consumer Lab conducted an independent study of various vitamin and mineral supplemtns and found:
Ten, or nearly one-third, of the multivitamins selected for testing were found to contain significantly more or less ingredient than claimed or were contaminated with lead. In addition, several products (including three for children) exceeded tolerable limits established by the Institute of Medicine for nutrients such as vitamin A, folic acid, niacin and zinc.
Overview of Vitamins and Minerals and their action in the body:Vitamin A Necessary to maintain good vision and skin. In supplements, "Vitamin A" usually refers to retinol (including retinyl palmitate and retinyl acetate) as well as beta-carotene. Retinol is found in animal-derived sources such as dairy foods and liver. Beta-carotene comes from fruits and vegetables, such as carrots and spinach. It is thought that beta-carotene is converted in the body into vitamin A based on the body's need for vitamin A and, therefore, may be a safer form of vitamin A to avoid potential overdosing.
B Vitamins:Thiamin (B-1) assists nervous function. It is found in yeast, peas, beans, enriched flour and whole grains in large enough amounts that supplementation is normally not necessary.
Riboflavin (B-2) maintains vision and the skin. Although found in many vegetables and nuts, as well as enriched flour, some supplementation may be needed in children and the elderly.
Niacin (B-3) helps release energy from carbohydrates. It is available in the diet from enriched white flour, as well as from peanuts, fish and meat.
Pyridoxine (B-6) is important in many aspects of metabolism and in maintaining the immune and nervous systems. B-6 is widely available in the diet, but marginal deficiency is believed to be relatively common in the developed world. Inadequate B-6may raise blood levels of the substance homocysteine, and elevated homocysteine may in turn increase risk of cardiovascular disease. On this basis, B-6 supplements have been suggested as a means of helping to prevent cardiovascular disease, but efficacy has not been proven.
Folic acid (Folate, Folacin or B-9) is known to reduce the risk of certain birth defects in offspring. Furthermore, adequate folate, along with vitamin B-6 and vitamin B12, are necessary to keep homocysteine levels low (see B-6 above). Good natural sources of folic acid include dark green leafy vegetables and oranges. Because folic acid is added to enriched grains and some other foods, most people get sufficient folic acid from their diet. Nonetheless, supplements are generally recommended for women who are pregnant or may soon become pregnant.
B-12 deficiency can cause anemia, and, if the deficiency is severe enough, irreversible nerve damage may occur. B-12 is also required, along with folate and B-6,to maintain low homocysteine levels. However, true deficiency of this vitamin is rare. Vitamin B-12 is found in abundant quantity in meat, dairy products and eggs, and the body can store enough B-12 to last for years. Note, though, that B-12 is not found at useful levels in any purely plant-based substance. For this reason, total vegetarians (vegans) need to take a B-12 supplement. Deficiency might also occur in people with low stomach acidity, such as seniors or those taking drugs that reduce stomach acid (such as Prilosec or Zantac). The reason is that stomach acid is required to separate B-12 from the proteins in which it is naturally found. People with low stomach acid can still absorb the purified B-12 found in supplements.
Vitamin C (ascorbic acid) is required for healthy blood vessel walls, gums, and bones. It is also a strong antioxidant. Vitamin C is found in many vegetables, such as broccoli and Brussels sprouts, as well citrus and other fruits, so that a healthful diet should allow one to meet the RDA.
Vitamin D (cholecalciferol) helps the body absorb calcium to promote strong bones and teeth. It can be obtained in sufficient amounts from fortified milks and foods and from exposure to sunlight. However, people who live in northern climates may easily become vitamin D deficient during the winter, especially if they are dark-skinned. Also, increased concern about skin cancer has caused people to avoid the sun, and this creates a potential risk of reduced vitamin D. There is some evidence that inadequate vitamin D intake can lead to an increased risk of various forms of cancer, including breast cancer.
Vitamin E (tocopherol) is an antioxidant. Most diets provide enough vitamin E to meet RDAs as it is easily obtained from food sources such as nuts, seeds, whole grains, vegetable oils, and the fatty part of meats.
Vitamin K plays a central role in blood clotting as well as bone formation. Foods, such as green leafy vegetables, can provide sufficient amounts, and intestinal bacteria also produce vitamin K. True deficiency is rare; however, there is some evidence that vitamin K supplements at doses higher than nutritional needs may help fight osteoporosis.
Minerals and Other IngredientsCalcium: While critical for strong bones and teeth, calcium is a very bulky material and most multis therefore do not contain the total recommended daily intake amount in a tablet, as it might make the tablet too large. Consequently, people should consider getting their calcium from a separate calcium supplement or fortified food or beverage.
Chromium plays a role in the body's regulation of blood sugar. Chromium is found in liver and whole-wheat products.
Copper is necessary for proper development of connective tissue, nerve coverings, and skin pigment. Copper is found in foods such as organ meats, oysters, nuts, and seeds and can be obtained in sufficient quantity from a good diet.
Iodine is needed for making thyroid hormones, and iodine deficiency causes hypothyroidism (low thyroid). However, iodine deficiency is uncommon in the developed world, and too much iodine can also cause hypothyroidism! Seafood and seaweeds provide iodine. In addition most table salt is now iodized and represents a good dietary source of iodine.
Iron deficiency is the leading cause of anemia. Deficiency is most common in menstruating woman and is also seen in some children and pregnant women. Adult men are seldom deficient in iron, and many multivitamins for adult men specifically leave out iron, because there are concerns that excess iron intake might increase risk of heart disease. Meat, poultry and fish are rich in iron. Dried fruits, grains and green leafy vegetables are also good sources, although iron from plant sources is absorbed only half as well as that from animal sources.
Magnesium assists metabolism and the nervous system. There is some controversy regarding whether marginal magnesium deficiency is a rare or a common occurrence. Whole grains, nuts and beans are good sources of magnesium.
Manganese is involved in bone formation and metabolism. Nuts, legumes, tea, and whole grains are rich sources of manganese and can provide adequate amounts.
Molybdenum is a constituent of various enzymes in the body and can be obtained from legumes, grain products, and nuts in the diet.
Selenium is used by the body in it its antioxidant system. There is some preliminary evidence that selenium supplements may help prevent certain forms of cancer, but this benefit appears to be limited to those who are deficient in the mineral, and deficiency is thought to be relatively uncommon in the developed world. Foods containing selenium include nuts, wheat germ, whole wheat, and orange juice.
Zinc plays a role in brain function, wound healing, and sperm production. Many breakfast cereals are fortified with zinc and it is naturally abundant in red meats, certain seafood, and whole grains. However, mild zinc deficiency is thought to be fairly common.
Too Much Folic Acid in a Vitamin Water
Glaceau Vitamin Water Multi-V, one of three vitamin waters selected, contained fifteen times of its claimed amount of folic acid. Although the label notes that there are 2.5 servings per bottle, ConsumerLab.com cautioned that drinking one bottle would provide 1,500 mcg of folic acid – an amount over the upper tolerable level for adults. Children should not get more than 300 to 600 mcg of folic acid per day – the amount in less than half a bottle of this product.
