Dietary Supplements
Dietary supplements include vitamins, minerals, amino acids, herbs, enzymes, and other compounds. Although dietary supplements are sold over the counter and often thought of as safe and natural, they may contain powerful bioactive chemicals that have the potential for harm. About one-quarter of all pharmaceutical drugs are derived from botanical sources, and even essential vitamins and minerals can have toxic effects if consumed in excess.
In the United States, dietary supplements are not legally considered drugs and are not regulated like drugs. Before they are approved by the FDA and put on the market, drugs undergo clinical studies to determine safety, effectiveness, side effects and risks, possible interactions with other substances, and appropriate dosages. The FDA does not authorize or test dietary supplements, and manufacturers are not required to demonstrate either safety or effectiveness before they are marketed. Although dosage guidelines exist for some of the compounds in dietary supplements, dosages for many are not well established.
Large doses of some dietary supplements can cause health problems by affecting the absorption of certain vitamins or minerals or interacting with medications. Garlic supplements, for example, can cause bleeding if taken with anticoagulant (blood-thinning) medications. Some supplements can have side effects. St. John’s wort, for example, increases the skin’s sensitivity to sunlight and may decrease the effectiveness of oral contraceptives, drugs used to treat HIV infection, and many other medications. For this reason, ask your doctor or a dietitian before taking any high-dosage supplement.
Dietary Supplements Photo Gallery
There are also key differences in the way drugs and supplements are manufactured: FDA-approved medications are standardized for potency, and quality control and proof of purity are required. Dietary supplement manufacture is not as closely regulated, and there is no guarantee that a product contains a given ingredient at all, let alone in the appropriate amount. The potency of herbal supplements can vary widely due to differences in growing and harvesting conditions, preparation methods, and storage. Contamination and mis-identification of plant compounds are also potential problems.
In an effort to provide consumers with more reliable and consistent information about supplements, the FDA has developed labeling regulations. Labels similar to those found on foods are now required for dietary supplements; for more information, see the box “Using Dietary Supplement Labels.”
Food Additives
Today, approximately 3000 substances are intentionally added to foods to maintain or improve nutritional quality, to maintain freshness, to help in processing or preparation, or to alter taste or appearance. The most widely used additives in foods are sugar, salt, and corn syrup; these three, plus citric acid, baking soda, vegetable colors, mustard, and pepper, account for 98% by weight of all food additives used in the United States.
Food additives pose no significant health hazard to most people because the levels used are well below any that could produce toxic effects. Two additives of potential concern for some people are sulfites, used to keep vegetables from turning brown, and monosodium glutamate (MSG), used as a flavor enhancer. Sulfites can cause severe reactions in some people, and the FDA strictly limits their use and requires clear labeling on any food containing them. MSG may cause some people to experience episodes of sweating and increased blood pressure. If you have any sensitivity to an additive, check food labels when you shop and ask questions when you eat out.
Foodborne Illness
Many people worry about additives or pesticide residues in their food, but a greater threat comes from microorganisms that cause foodborne illnesses. Raw or undercooked animal products, such as chicken, hamburger, and oysters, pose the greatest risk, although in recent years contaminated fruits and vegetables have been catching up. And one in 10,000 eggs may be contaminated with Salmonella inside the egg shell.
The Centers for Disease Control and Prevention (CDC) estimates that 48 million illnesses, 128,000 hospitalizations, and 3000 deaths occur each year in the United States due to foodborne contaminants. One out of six people contract a food-borne disease each year. Symptoms include diarrhea, vomiting, fever, pain, headache, and weakness. Although the effects of foodborne illness are usually not serious, some groups, such as children, pregnant women, and elderly people, are more at risk for severe complications such as rheumatic diseases, seizures, blood poisoning, and death. Young children and older adults are more likely to have severe complications
