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WHAT HAPPENS IF I TAKE MORE VITAMINS AND MINERALS THAN I NEED? HOW MUCH IS TOO MUCH? These are common concerns, fuelled by media reports linking vitamin C with kidney stones and warnings against vitamin A in pregnancy. How much is fact and how much is fiction? The optimal intake of a nutrient varies considerably for each individual depending on their age, sex, health and numerous other factors. Therefore it is to be expected that the level of a vitamin that would induce signs of toxicity also varies considerably. When certain illnesses are present, a person’s need for a vitamin can increase dramatically. Vitamin C is the prime example of this when a person is fighting an infection. Here, I have erred on the side of caution by listing the levels of nutrients that may induce toxicity in a small percentage of people, both if taken over a short period of time (up to one month), and over a long period of time (three months to three years), indicating which symptoms persist and which go away once the high level is reduced. It’s important to realize that just about everything is toxic if the dose is high enough. In 1990 a man died of drinking 10 liters of water in 2 hours. The greatest risk from the drug Ecstasy, say doctors from the
The general conclusion from a survey of the results of over one hundred research papers in proper scientific journals is that for the majority of vitamins, with the exception of vitamin A and D, levels 100 times greater than the US RDA are likely to be safe for long-term ingestion. In practical terms, this means that the chances of having a toxic reaction to even the higher dose supplements available in health food shops, is extremely unlikely unless you take a considerably greater number of tablets than recommended. This is broadly consistent with the public health record of deaths attributed to nutritional supplements. For example, a survey of Local Poison Control Centers in the
VITAMIN A Vitamin A comes in two forms: the animal form, retinol, which stores in the body; and the vegetable form, beta-carotene, which is converted into retinol, unless body levels are already high. Beta-carotene is therefore not considered toxic, with the exception that excessive intake can cause a reversible yellowing of the skin. There are a number of incidences of adverse reactions to retinol, usually from intakes of 500,000ius of more over a considerable length of time. The symptoms include peeling and redness of the skin, disturbed hair growth, lack of appetite and vomiting. According to Dr. John Marks, medical director at
A number of cases of toxicity and birth defects have been reported for a synthetic relative of vitamin A, isotretinoin, sold as the drug Roaccutane. These reports of birth defects have been wrongly extended to natural vitamin A. Five cases of birth defects have been reported in women taking large amounts of retinol (25,000 to 500,000ius per day) however no clear cause and effect relationship has ever been established in any of these cases. Other studies have shown that women who supplement their diet with multivitamins including vitamin A usually at a level of 7,500 to 25,000iu have a lower incidence of birth defects. One study published last year found a possible association. In a study of 22,747 women, of whom 121 gave birth to children with the kind of defect associated with, among other things, vitamin A toxicity. Of these 121 two of the cases could have been attributable to supplementing in excess of 10,000ius of vitamin A in the form of retinol. In view of the possibility that retinol, in large amounts, could induce birth defects, it is wise for women of a child bearing age to supplement no more than 10,000ius of retinol. The same caution does not apply to beta-carotene. VITAMIN D Of all the vitamins, vitamin D is the most likely to cause toxic reactions. Vitamin D encourages calcium absorption and excessive intake can lead to calcification of soft tissue. However the levels that create this effect are certainly in excess of 10,000ius and probably more like 50,000ius. A daily intake not exceeding 2,000ius for adults and 1,000ius for children is generally considered to be safe. VITAMIN E Vitamin E has been well researched for toxicity. A review of 216 trials of high dose vitamin E in 10,000 patients showed that daily doses of 3,000ius for up to eleven years and 55,000ius for a few months had no detrimental effect. However, adverse reactions have occasionally been reported at lower levels of 2,000ius, especially in children, possibly due to an allergic reaction to the source of the vitamin E. Vitamin E appears to potentiate the anti-clotting effects of the drug Warfarin, and therefore high levels are not recommended for those on Warfarin. High levels are also best avoided by those suffering from rheumatic fever. Some old reports that vitamin E should not be supplemented by those with breast cancer are inaccurate. It is highly beneficial to supplement in this condition. A daily intake of up to 1,500iu is considered safe. VITAMIN C Vitamin C is water soluble and therefore excess is readily excreted from the body. RDA’s vary considerably from country to country. A general consensus, based on up to date research, is that 100mg a day represents a good basic intake. The optimal intake is probably between 1,000 and 3,000mg a day. A number of studies have investigated the effects of vitamin C of specific diseases using over 10,000mg a day. The recommendation of these high levels have attracted controversy and allegations that vitamin C can cause kidney stone formation, interferes with B12 absorption, and causes a ‘rebound scurvy’ when supplementation is stopped. All of these allegations have been shown to be without substance. The only adverse effect of taking large amounts of vitamin C is that it can have a laxative effect. Generally, supplementing up to 5,000mg of vitamin C can be considered safe. B VITAMINS B vitamins are water soluble and excess is readily excreted from the body via the urine. Hence they are generally of very low toxicity. Thiamin (B1), riboflavin (B2), pantothenic acid (B5), B12 and biotin show no sign of toxicity at levels of at least 100 times the US RDA. Vitamin B3, in the form of niacin, causes a blushing sensation at levels of 75mg or more. This is part of its natural action and therefore is not generally considered to be a toxic effect. According to Dr. John Marks, director of medical studies at Girton College, Cambridge, "doses of 200mg to 10g daily have been used therapeutically to lower blood cholesterol levels under medical control for periods of up to ten years or more, and though some reactions have occurred at these very high dosages, they have rapidly responded to cessation of therapy, and have often cleared even when therapy has been continued." Levels of up to 2,000mg per day on a continuous basis are considered safe, although they will induce blushing (vasodilation). Vitamin B6 has been extensively tested for toxicity by a number of research groups including the
The safety of minerals depends on three factors. Firstly, the amount. All minerals show toxicity at exceedingly high doses. Secondly, the form. Trivalent chromium, for example, is essential, while hexavalent chromium (found in neither foods nor supplements) is very toxic. Thirdly, the balance with other minerals in the diet. Iron supplementation can exacerbate zinc deficiency since it is a zinc antagonist. The reason for this antagonism is that many minerals are atomically very similar to each other. They’re just different sizes of cogs. So if you lack one mineral but take in an excess of another similar mineral it can slot into the wrong enzyme, speeding up or slowing down or simply blocking the enzyme from working. In view of these factors the levels given as safe for long term ingestion in the following text presuppose that other essential minerals are also adequately supplied. Larger amounts than those stated may also be safe for short term ingestion, particularly for people with certain illnesses which result in an extra requirement for a mineral. Selenium requirement, for example, is thought to increase in certain types of cancer. CALCIUM Calcium comes in many forms, the best absorbed of which include calcium ascorbate, amino acid chelate, gluconate, orotate and carbonate. In normal, healthy people there is little danger of toxicity since the body excretes excessive amounts. Some cultures consume in excess of 2g a day from diet alone, so this amount is certainly considered safe. 3.6g per day is used to treat calcium deficiency disorders. Problems of excessive calcium arise from other factors such as excessive vitamin D intake (above 25,000ius per day), parathyroid or kidney disorders. Calcium interacts with magnesium and phosphorus, therefore calcium supplementation should only be given to those with an adequate magnesium and phosphorus intake, or also supplementing these elements. Phosphorus is rarely deficient while magnesium deficiency is quite common. The ideal calcium/phosphorus ratio is probably 2/1. Less than 1/2 is not desirable. The ideal calcium/magnesium ratio is probably 3/2. MAGNESIUM Magnesium comes in many forms, the best absorbed of which include magnesium aspartate, amino acid chelate, gluconate, orotate and carbonate. Toxic effects of magnesium include flushing of the skin, thirst, low blood pressure, loss of reflexes and respiratory depression. Toxicity is only likely to occur in those with kidney disease taking magnesium supplements. For normal, healthy adults a daily intake of up to 1,000 mg is considered safe. Magnesium interacts with calcium, therefore magnesium supplements should only be given to those with adequate calcium intake, or supplementing calcium. The ideal magnesium/calcium ratio is probably 2/3 and, in cases of magnesium deficiency 1/1. IRON Iron is one of the most frequently deficient minerals. At least 6 per cent of women in the
Iron is antagonistic to many other trace minerals including zinc which is commonly deficient, especially among pregnant and lactating women. Therefore extra iron should not be supplemented without ensuring adequate zinc status or supplementing zinc. The normal requirement for zinc and iron is approximately equal. ZINC Zinc is one of the most thoroughly researched and commonly deficient minerals. About a thousand papers are published each year indicating its value for a variety of conditions. The best absorbed forms of zinc include zinc picolinate, amino acid chelate, citrate and gluconate. Zinc supplementation is relatively non-toxic. In doses of 2,000mg symptoms of nausea, vomiting, fever and severe anemia have been reported. Small amounts of zinc, particularly in the form of zinc sulfate, can act as an irritant in the digestive tract when taken on an empty stomach. There is also some evidence that zinc, at levels of 300mg per day, may impair rather than improve immune function. It is generally considered safe to supplement up to 50mg per day. Zinc is an iron, manganese and copper antagonist therefore an adequate intake of these minerals is advisable if large amounts of zinc are taken over a long period of time. Manganese is very poorly absorbed and therefore it is generally advisable to supplement half as much manganese as zinc if more than 20mg of zinc is supplemented per day. The normal requirement for zinc is about ten times that of copper. Since the average intake of copper for those on a healthy diet is in the order of 2mg, those supplementing more than 20mg of zinc may be advised to add 1mg of copper for each additional 10mg of zinc. It is also best to ensure that at least 12mg of iron is supplemented when taking more than 20mg of zinc. COPPER Copper deficiency is quite rare, probably because we receive it from drinking water as well as from unrefined foods. The best absorbed forms of copper include copper amino acid chelate and gluconate. Requirements are low (2mg per day) and only 5mg a day are required to correct deficiency. Copper toxicity does occur, mainly due to excessive intake as a result of copper plumbing. Copper is also a strong antagonist of zinc and for this reason it is advisable not to supplement more than 2mg or a tenth of one’s intake of zinc. Copper also depletes manganese. MANGANESE Only 2 to 5 per cent of dietary manganese is absorbed and therefore larger intakes have a small effect on overall body levels. The better forms for absorption include amino acid chelates, gluconates and orotates. There is some evidence that vitamin C may help the absorption of manganese. In animals it is one of the least toxic of all trace elements. Toxicity has never been reported in man. A daily intake of up to 50mg is considered safe. Excessive zinc or copper intake interferes with manganese uptake. SELENIUM Selenium is required in very small amounts of 25 to 200mcg per day. It comes in two forms: organic such as selenomethionine or selenocystine, sometimes in the form of selenium yeast; and inorganic sodium selenite. The inorganic form is more toxic, with toxicity occurring at levels of 1,000mcg or more. The organic forms show toxicity above 2,000mcg. No toxicity has been reported with either form at intakes of 750mcg. An intake of up to 500mcg for an adult is generally considered safe. In view of the relatively small difference between a beneficial and a detrimental intake, selenium should also be kept out of reach of children. CHROMIUM Chromium is found in two forms in nature - hexavalent and trivalent. Hexavalent chromium is much more toxic, however it is neither found in food nor supplements so contamination can only occur from occupational exposure. The better absorbed forms of chromium are picolinate and amino acid chelate. Trivalent chromium has a very low toxicity partly because so little is absorbed. Cats show signs of toxicity at 1,000mg per day. An intake of up to 500mcg is certainly considered safe. Do's & Don'ts of Supplement Taking Very few problems can or do occur with vitamin supplements, however it is good to be aware of the following: Vitamin A (as retinol) in doses in excess of 10,000ius (3,000mcg) should not be given to a pregnant woman or women trying to conceive. There is a theoretical risk, based on animal studies, that very large amounts of retinol could be undesirable during pregnancy. The same caution does not apply for beta-carotene, the vegetable form of this vitamin. Beta-carotene, in excess, makes your skin go yellow. if you have excessively yellowing skin check your beta-carotene intake from food and supplements. This is quite different to jaundice or hepatitis in which the eyes go yellow. It is harmful but indicates you have more than enough beta-carotene in your diet. Vitamin B2 (riboflavin) makes your urine bright yellow. This is normal. Vitamin B3 in the form of niacin, usually in doses of 100mg or more, can make you flush, go red, hot and itchy for up to 30 minutes. This is normal and is not an allergy. While beneficial as it improves circulation and detoxification, if you do not like it, take less or take half the dose twice a day. Your flushing potential reduces with regular supplementation. Vitamin C has a laxative effect in very high doses, normally above 5 grams a day. Some people are very sensitive, even at 1 gram a day, while others can tolerate 10 grams a day. The ideal level is the ‘bowel tolerance’ level, which is the level below that that result in loose bowels, so adjust your intake accordingly. THE SIDE-EFFECTS The side effects of optimum nutrition are increased energy, mental alertness and a greater resistance to disease. In fact, a survey of supplement takers found that 79 per cent noticed a definite improvement in energy, 66 per cent felt more emotionally balanced, 60 per cent had better memory and mental alertness, skin condition improved in 55 per cent of people, and, overall 61 per cent had noticed a definite improvement in their well-being. As long as you stick to the levels given in this website and don’t take toxic levels, explained above, the only side effects are beneficial. A small number of people do, however, experience slight symptoms on starting a supplement program. This may be because they take too many supplements with too little food, or perhaps because a supplement contains something that doesn’t agree with them, for example, yeast. These problems are usually solved by stopping the supplements, then taking one only for four days, then adding another for the next four days and so on until all supplements are taken. This procedure will usually identify if there is a supplement that is causing a problem. More often than not the problem simply goes away. Sometimes people feel worse before they feel better. Imagine if your body is coping with the onslaught of pollution, poor diet, toxins and stimulants, and suddenly gets a wonderful diet and all the supplements it needs. This can lead to ‘detoxification’, the body cleansing itself. This is not a bad thing and usually subsides within a month. However, if you have inexplicable symptoms on starting a supplement program or are suffering in any way see a clinical nutritionist.
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