Vitamin and Mineral Supplements: Buy with Care
If you choose to take vitamin and mineral supplements, pick one that contains no more than 150 percent of the Reference Daily Intake (RDI) for each nutrient. Some nutrients can be toxic in high doses, and much is still unknown about toxicity levels. Supplements of iron, zinc, chromium, selenium and other minerals can be toxic at levels not much higher than the recommended allowances. High levels (daily vitamin A intake of greater than 25,000 IU) can cause headaches and liver damage. More than 1,000 mg of vitamin C can cause cramps and diarrhea and may interfere with the body's ability to use other nutrients.
Natural and synthetic vitamins are virtually identical. Synthetic vitamins are cheaper to make because it would require mountains of natural foods to extract enough material to make all the vitamins sold. (The one exception is vitamin E: The natural form is biologically more active than the synthetic version. This has been taken into account, so when you but 30 IU of synthetic vitamin E, you're getting the same as 30 IU of the natural form.)
- Always check the expiration dates.
- It's OK to buy supplements containing sugar and starch; they are sometimes added to ensure better nutrient absorption.
- Store brands may be just as good as name brands, and are sometimes made by the same manufacturer. These no-name brands are less expensive because you're not paying for advertising.
Daily, all purpose vitamins with mineral supplements are very safe when taken as directed. The same cannot be said for herbal products, so use caution if you take them. Herbal preparations are not standardized for dose or regulated for safety. In recent years, popular supplements such as Ma huang (used in energy-boosting and weight-loss products) and Jin Bu Huan (promoted as a sleep aid and pain reliever) have caused serious problems.
Other herbal remedies have run into problems stemming from contamination in the manufacturing process. Most cases of herbal toxicity, however, probably stem from the chemistry of the plant itself. Until there are stricter regulations on the manufacturers of herbs and supplements, be cautious. If you take these products, take only small quantities of any single preparation, check that the package lists the actual plants used in the preparation, and let your doctor know what products you're consuming. Also, never take herbal supplements if you are trying to get pregnant, are pregnant or are breast-feeding.