Supplements are extra sources of dietary components that are available in pill, powder or liquid form. They are intended to be taken by mouth and nutritionally supplement the diet. They may include vitamins, minerals, herbs or other substances (e.g., amino acids, enzymes, probiotics, hormones). Tens of thousands of products in the United States are marketed as dietary supplements. Multivitamins and minerals make up the largest group of these products. 

The use of supplements may ensure that people with inadequate nutrition receive adequate amounts of essential nutrientsessential nutrients to promote good health and performance. Supplements may be recommended for people who receive insufficient nutrients (due to a poor diet or too few foods consumed), have certain medical conditions (e.g., food intolerance), lifestyle choices (e.g., excessive drinking, smoking) or at certain stages of life (e.g., during pregnancy, menopause, older adults).

Most responsible nutrition organizations recommend that people receive their daily nutritional requirements through food instead of using supplements. Supplements can interact with medications (both prescription and over-the-counter), other supplements and certain medical conditions. Side effects may range from bothersome to deadly.

Receiving needed nutrients from food is less likely to lead to a toxic buildup of certain substances within the body. In addition, multiple varieties of nutrients may be available in a single food source, and additional health benefits can be obtained from foods (e.g., phytochemicals) that may not necessarily be provided in a supplement.

Supplements are not intended to treat diseases or medical conditions, replace prescription medication or make up for poor dietary choices.

Manufacturers or distributors of supplements are responsible for determining that their products are safe and their product claims are substantiated by adequate evidence to show they are not false or misleading. Some supplements have convincing scientific evidence supporting their claims. In most cases, however, there is a lack of independent and well-designed scientific studies on supplements.

The U.S. Food and Drug Administration (FDA) is responsible for overseeing labeling requirements for supplements. Certain information is required on supplement labels and only certain types of product claims can be made. The advertising of supplement products is regulated by the U.S. Federal Trade Commission.

There are certain things to look for when purchasing supplements. These include reading product labels carefully, using supplements appropriately and avoiding megadoses (more than 100 percent of the daily value) of any one dietary ingredient. Recommended daily levels are available for certain vitamins and minerals, although not for herbal supplements or other non-nutrient supplements.

As the name implies, dietary supplements are intended to supplement and not replace food from the diet. Supplements are not considered a food or a drug. Energy bars or high-calorie, fortified treats may be considered a supplement when they are represented to be the sole item of a meal or diet. Most importantly, supplements are required by the U.S. Food and Drug Administration to be labeled a “supplement.”

Supplements contain one or more dietary ingredients intended to provide nutritional value to the human body. New dietary ingredients are those sold in the United States after October 1994 (when the Dietary Supplement Health and Education Act was enacted), and are subject to additional regulations.

Generally, healthy people who eat a variety of foods do not need supplements. Diets high in fiber, low in fat, that include a variety of fruits and vegetables (five to nine servings per day) and whole grains provide a balanced level of nutrients for most people.

However, the use of supplements may be recommended in some cases. These may include:

• Insufficient dietary nutrients. People who consume too little food (e.g., less than 1,200 calories per day), too small a variety of foods or engage in poor dietary choices (e.g., diets high in fast foods or processed foods) may not get enough nutrients through diet alone. In addition, vegetarian diets may result in deficiencies of calcium, iron, zinc and vitamins B12 and D, depending on the categories of foods not consumed.
  
  
• Medical conditions that affect nutrient absorption, use or excretion. Allergies or certain food intolerances (e.g., lactose intolerance) may result in specific nutritional deficiencies (e.g., calcium). Difficulty absorbing nutrients can result from a variety of disorders, including liver, gallbladder, intestinal (e.g., Crohn’s disease) or pancreatic diseases. Surgeries affecting the digestive tract and certain medications may also affect nutrient absorption, use or excretion.
  
  
• Pregnancy. Women may need more of certain nutrients during pregnancy (e.g., calcium, folate and iron). Adequate levels of folate are important before and early in pregnancy to reduce the risk of certain birth defects (e.g., spina bifida). Iron is also important during pregnancy to help prevent fatigue.
  
  
• Menopause. Women going through menopause may require extra nutrients, due to a drop in levels of the hormone estrogen. Calcium and vitamin D supplements may help reduce the risk of osteoporosis in these cases.
  
  
• Heavy menstrual bleeding. Women who lose significant amounts of blood during menstruation may experience an iron deficiency, which can lead to anemia.
  
  
• Old age. Older adults may experience a lack of adequate nutrition due to reduced appetite. This may occur in conjunction with a variety of illnesses that are more prevalent among older adults. Ill-fitting dentures as well as hormonal or other biological changes can result in a loss of adequate nutrients among older adults.
  
  
• Smoking. Tobacco hinders the absorption of many different types of vitamins and minerals (e.g., vitamin C, folate, magnesium, calcium). People who smoke may benefit from certain types of supplements.
  
  
• Excessive drinking. Consuming alcohol in large quantities over a long period of time can impair digestion and the absorption of certain vitamins and minerals (e.g., vitamin B1, iron, zinc, magnesium, folate). Excessive drinking has been defined as more than two drinks per day for men under 65 and more than one drink per day for all women or men over 65.
  
  
• Limited dairy product consumption or sun exposure. People who do not or cannot consume milk, or who do not receive at least 10 to 15 minutes of exposure to sunlight per day may not receive enough vitamin D.  

The use of supplements is widespread. Tens of thousands of products in the United States are marketed as dietary supplements. Multivitamins and minerals that contain a variety of dietary ingredients make up the largest proportion of these products.  

All dietary supplements are intended to nutritionally supplement the diet and be taken by mouth. They can take many forms, including pill, tablet, capsule, liquids or powders. They may come in the form of energy bars or beverages – but these supplements are not intended or represented to be the sole item of a meal or diet. Certain supplements are available in lozenge or chewable form, although these often contain additional ingredients such as sugar to enhance their taste.

The dietary ingredients in supplements may include one or more of the following:

• Vitamins. A variety of organic substances that can be found in foods from plant and animal sources. Fourteen vitamins are essential for human metabolism, growth and development, and cell function. These are: vitamins A, C, D, E, K and the B vitamins (B6, B12, biotin, folate, niacin, pantothenic acid, riboflavin, choline and thiamine). All of these vitamins can be obtained from foods. Two of these may also be created by the human body under certain circumstances. Vitamin D can be created by the body after small amounts (e.g., 10 to 15 minutes) of exposure to sunlight. Vitamin K may be produced by bacteria in the intestines.
  
  Each vitamin has a specific effect in the body. For example, vitamins A, C and E act as antioxidants, which can help prevent damage to cells. Vitamin K helps blood clot and may help prevent hemorrhaging. Vitamins are either water soluble (vitamin C, B vitamins) or fat soluble (vitamin A, D, E, K). This affects whether the vitamin can be stored in body tissues or excreted by urine.
  
  Multivitamins contain a variety of vitamin types and are intended to be a convenient way to supplement the diet (usually one is taken per day) for normal healthy adults.  It is generally recommended that a multivitamin should contain 100 percent DRI (Dietary Reference Intake) or less for each ingredient. They may also contain certain minerals (e.g., calcium, iron, zinc).
  
  
• Minerals. A chemical element or compound found in trace amounts in a variety of foods. Minerals do not come from plant or animal sources, but rather from the earth (e.g., in the soil). Certain minerals are necessary in small amounts to help regulate body function and maintain good health. The human body does not produce minerals, so all minerals the body needs must be consumed, either in food or supplement form. Certain minerals (macrominerals) are required by the body in larger amounts than others (trace minerals).
  
  Different minerals have specific effects on the body. For example, iron is necessary for the production of red blood cells, calcium helps strengthen teeth and bones, and sodium helps regulate fluid levels in the body. While sodium is considered an essential mineral, it is not usually taken as a supplement because it is so common in foods and beverages.
  
  
• Herbal supplements or other botanicals. Plants or parts of plants used for cooking, tea and medicinal or therapeutic purposes. Some of these products have been used for hundreds of years, although scientific evidence of their efficacy and safety is rarely conclusive. Herbs may be associated with a wide range of effects on the body. Examples of these types of dietary ingredients include echinacea, ephedra, ginkgo biloba, ginseng and St. John’s wort.
  
  
• Other substances found in supplements include:
  
  
• • Amino acids (e.g., branched chain amino acids)
    
    
  • Enzymes and hormones (e.g., coenzyme Q10, DHEA, melatonin)
    
    
  • Ergogenic aids (e.g., chromium picolinate, creatine)
    
    
  • Glucosamine and chondroitin (supplements for certain painful conditions)
    
    
  • Phytochemicals (e.g., carotenoids, beta-carotene)
    
    
  • Probiotics (e.g., lactobacillus acidophilus)
    
    
  • Zoochemicals (non-nutrient chemicals from animal sources, such as conjugated linoleic acid)
    
    
  • Omega-3 fatty acids (e.g., fish oil, flaxseed)
    
    
  • Soluble fiber (e.g., psyllium)
    
    
  • Spirulina (e.g. blue green algae)
    
    
  • Tissue (e.g., shark or bovine cartilage)

Almost all substances that affect the body (including supplements) can have both positive and negative effects.  

The use of supplements may ensure that people with inadequate nutrition receive adequate amounts of essential nutrients to promote good health and performance.

Many supplements have proven health benefits and may be used to help protect against certain diseases or disorders. For example, the American Heart Association recommends that people at risk of cardiovascular disease take supplements containing omega-3 fatty acids. Calcium supplements can help reduce the risk of osteoporosis in postmenopausal women. Folic acid supplements taken before and during pregnancy may help prevent certain birth defects (e.g., spina bifida). Some evidence suggests that the herb St. John’s Wort may help some people with mild depression.

Supplements may also be used to correct deficiency diseases, such as anemia (iron deficiency), pellagra (niacin deficiency) and beriberi (thiamine deficiency), goiter (iodine deficiency) and scurvy (vitamin C deficiency).

Research continues to discover potential new benefits of many supplements. For example, one recent study found that people who take folic acid supplements may retain more of their ability to hear low-frequency sounds as they get older. Another study found children may have improved hand-eye coordination if their mothers take fish oil supplements during pregnancy.

In contrast, some other studies have failed to confirm claims made for supplements. Recent research indicates that taking calcium supplements during childhood probably does not reduce the risk of aging-related fractures later in life.  

It is important to note that these findings have not yet been confirmed by broader research.

Supplements have limits. They cannot:

• Replace prescription medication
  
  
• Treat or cure diseases or medical conditions (e.g., high blood pressure)
  
  

• Make up for a poor diet or bad habits (e.g., smoking, physical inactivity)
  
  

• Work miracles (e.g., promote weight loss without exercise or reducing calories)

Supplements may also interact with prescription or over-the-counter drugs, other supplements, and even components of conventional foods or beverages. Side effects may range from bothersome to deadly. Supplements may also interfere with surgery or recovery from surgery (e.g., ginseng). Certain supplements may not be appropriate for people with certain diseases or medical conditions. For example, vitamin C is not recommended for people with hemochromatosis because it may contribute to iron accumulation in people with this condition. Likewise, ginseng may adversely affect blood sugar levels in patients with diabetes.  

Examples of possible supplement interactions include:

Almost any nutrient (including supplements) can be toxic if taken in large quantities. Excess amounts of certain supplements may lead to the following:

It is unclear what levels of certain supplements, especially herbs or other botanical products, are safe. For many, it is not known at what point some dietary ingredients become excessive and can lead to negative effects on a person’s health. It is important to read any warnings on the label regarding supplement use. However, manufacturers are not required to list warnings on the label, so consumers are advised to contact the manufacturer for information about any possible warnings or side effects of their product.

Herbal dietary ingredients that may pose serious health problems include:

• Aristolochic acid. A potential carcinogen that can cause permanent kidney damage.
  
  
• Chaparral. May cause sudden, irreversible liver and kidney damage.
  
  
• Comfrey. A possible carcinogen that may cause liver damage.
  
  
• Ephedrine/ephedra sinica/epitonin. A stimulant that can be especially dangerous when mixed with other stimulants (e.g., caffeinated products). Possible effects range from nervousness to seizures, heart attack and death.
  
  
• Lobelia. Particularly dangerous to people with heart disease, it may cause breathing problems, low blood pressure and death.
  
  
• Germander. May cause liver disease and death.
  
  
• Magnolia-stephania preparation. May lead to kidney failure.
  
  
• Willow bark. This herb has chemical components (salicylates) that can have similar effects to aspirin. Potential adverse effects include Reye syndrome (fast-acting and potentially fatal disease in children under 18 associated with aspirin use following a viral infection) and possible allergic reactions.
  
  
• Wormwood. May cause neurological effects such as arm or leg numbness, delirium and paralysis.
  
  
• Yohimbe. May result in kidney failure, stomach problems, fatigue, seizures, paralysis and death.  

Certain supplements taken for long periods of time may also cause problems. For example, echinacea taken every day for more than two months may damage the liver. This risk is increased in patients taking other medications that may cause liver damage.

There are many types of supplements that may be unsafe in certain circumstances. For example, some types of hormone supplements (e.g., androstenedione) may be harmful when used by adolescents whose bodies are still developing. Parents should consult their child’s physician or a registered dietitian before providing any type of supplement to children or teenagers. 

Symptoms of adverse reactions that may occur with supplements includes:

• Abdominal pain
• Nausea
• Headache
• Hair loss
• Skin rash
• Fatigue
• Dizziness
• Diarrhea (may be black or bloody)
• Shock
• Liver or kidney damage
• Coma
• Birth defects

Many organizations associated with nutrition recommend that people receive all their daily nutritional requirements through food instead of using supplements. These organizations include the American Dietetic Association, American Heart Association (AHA), National Academy of Sciences and the National Research Council.

The AHA makes an exception for omega-3 fatty acids because this substance is difficult to get in sufficient quantities through diet alone. According to the AHA, people at risk for cardiovascular disease may benefit from increased amounts of omega-3, which can be obtained from supplements. The AHA recommends that people who fit this profile consult with their physician about the potential benefits of taking omega-3 supplements.

In addition, certain populations may benefit from supplement use. For example, physicians recommend that a woman who is pregnant take folate. The physician may also recommend calcium and/or iron supplements if the woman is not able to get adequate levels of these vitamins and minerals through diet alone. People who consume certain types of vegetarian diet, those with allergies or food intolerances, and older adults may benefit from the use of supplements. Anyone in doubt about whether supplements are appropriate for them should consult their physician or a registered dietitian.

Relying on supplements may give people a false sense of security about their level of protection against certain diseases. People using supplements may be less likely to seek needed medical care for ongoing health problems. In general, supplement use has a tendency to encourage self-diagnosis and care instead of seeking proper medical attention.  

Benefits of obtaining daily nutrients from food (instead of also using supplements) include:

• Safety. An overdose of nutrients rarely occurs from food sources, but can easily occur with supplements. In addition, tolerance levels may differ among people, and it can be easy to receive toxic levels of certain nutrients by consuming a single pill or liquid.  Also, some dietary ingredients are more safely received in conventional foods or beverages. For example, drinking green tea is generally considered safe but green tea supplements may actually be harmful. Many supplements can result in adverse side effects in people with certain medical conditions and may interact with current medications (prescription or over-the-counter).
  
  
• Added nutrients. Most whole foods contain more than just one type of nutrient. For example, an orange contains vitamin C, calcium, fiber and other essential nutrients. Supplements (except for multivitamins) may provide only one specific type of nutrient. It is easier to meet a wide variety of nutritional needs through food sources than through supplements.
  
  
• Specific health benefits. Many foods (plant- and animal-based) contain non-nutrient chemicals or compounds that are associated with specific health benefits, in addition to their basic nutrients. For example, there are hundreds of phytochemicals in plant foods that are associated with reduced risks of cancer and heart disease. Many act as antioxidants, which help prevent cellular damage in the body. Certain fatty acids (e.g., omega-3 fatty acids, conjugated linoleic acid) from animal sources can help reduce blood cholesterol levels and the risk of some cancers. Although some of these are available in supplements, it is much more difficult to get all the health benefits available from foods in the form of supplements. Also, in some cases, when certain substances are taken in supplement form, they do not provide the same level of health benefit as when they are consumed in food (e.g., the phytochemicals lycopene and flavonoids).
  
  
• Reliability and cost. For many over-the-counter supplements, especially herbs and botanical products, the strength of the scientific evidence is not conclusive. There have not been enough scientifically valid research studies performed to determine the potential benefit and risks of these products. Some experts have also argued that using supplements is expensive and may offer no real return for the money spent on them.

The safety and labeling of supplements in the United States are governed by the Dietary Supplement Health and Education Act (DSHEA). Enacted in 1994, DSHEA defines which products are considered supplements (products taken by mouth that contain a dietary ingredient intended to supplement the diet) and establishes how they are to be regulated. Prior to DSHEA, supplements were regulated as a type of food.

Under DSHEA, manufacturers or distributors of supplements are responsible for determining their products are safe, and their product claims are substantiated by evidence to show they are not false or misleading. However, these companies are not required to provide this evidence to any government agency prior to marketing or distributing their product.

An exception applies to new dietary ingredients (those introduced after DSHEA was enacted). In these cases, the manufacturer/distributor is required to supply the U.S. Food and Drug Administration (FDA) with the evidence it relied upon to substantiate that the claims are truthful and not misleading. Even so, most supplements in the marketplace today have not been reviewed or approved by the FDA.

Some supplements have convincing scientific evidence supporting their claims. However, in most cases, there is a lack of well-designed scientific studies regarding the effect of supplements.

The FDA is responsible for overseeing labeling requirements for supplements. Certain information is required on supplement labels, and only certain types of product claims can be made regarding supplements. Product advertising of supplements is regulated by the U.S. Federal Trade Commission.

Supplements are required by law to contain the following information on product labels:

• Statement of identity.  The name of the product (e.g., vitamin C, ginseng) and the identifier, “supplement” (e.g., herbal supplement). If the product is botanical (e.g., an herb), the plant or plant part must be identified.
  
  
• Net quantity of contents. The total number of pills or volume of liquid contained in the product.
  
  
• Directions for use. Instructions on how to use the product (e.g., one capsule daily)
  
  
• Supplement Facts Panel. This should include serving (dosage) size, amount per serving and percentage of daily value per serving (e.g., 1 tablet, Vitamin C, 1000 mg, 1667 percent daily value). This information is contained in a bordered area of the label. Serving size is determined by the manufacturer.
  
  
• Other ingredients. This may include ingredients added for color, safety (e.g., preservatives) or taste, and is usually in the “Supplement Facts” panel on the label. These ingredients are not required to be listed in order of the predominance within the product.
  
  
• Name and place of manufacturer, packer or distributor. This usually includes company name and city and state where they are located.

Supplement labels may also contain the following information (although federal regulations do not require it):

• Warnings and cautions (e.g., product should not be used if pregnant)
  
  
• Interactions and possible side effects
  
  
• Expiration date (if applicable)

In addition, the following types of claims may also appear on supplement labels:

• Structure-function claims. Describes the effect of dietary ingredients on body structure or function (e.g., vitamin C is a powerful antioxidant that boosts the immune system). These claims may not imply or state an association with a disease or medical condition – except in the case of deficiency diseases, which may be mentioned as long as the national prevalence of the disease is also mentioned. Structure-function claims must including a disclaimer that: 1) the FDA has not evaluated the claim; and 2) the product is not intended to diagnose, treat, cure or prevent any disease. These types of product claims are commonly used on supplement labels.
  
  
• Nutrient content claims. Describes comparative references to nutrient levels in a product (e.g., excellent source of calcium). These claims are regulated by the FDA.
  
  
• Health claims. Confirmed statements about the relationship between dietary ingredients and risk of disease. Claims are approved by the FDA based on significant scientific agreement. Qualified health claims are statements about a developing relationship between dietary ingredients and risk of disease. Claims are approved by the FDA based on credible scientific evidence and must include a disclaimer on the limitations.
  
  FDA-approved health claims for supplements include:
  
  
• Folate (reduced risk of neural tube birth defects)
  
  
• Calcium (reduced risk of osteoporosis)
  
  
• Soluble fiber from oat bran and psyllium (reduced risk of cardiovascular disease)
  
  
• Omega-3 fatty acids (reduced risk of cardiovascular disease)

The FDA also monitors supplement safety through voluntary adverse event reporting. If a dietary ingredient in a supplement has a significant or unreasonable risk of illness or injury, the FDA can take action to remove the product from the market. However, adverse effects must be reported to the FDA before this can occur. Even then, the FDA has to prove the supplement is unsafe.

For example, the herbal supplement ephedra was banned from the marketplace by the FDA in 2004, after it had been associated with numerous complaints (e.g., cardiovascular problems) and the much-publicized death of a professional baseball player. In 2005, a federal district court in Utah overturned the FDA ban with regard to products sold in that state, because the FDA failed to prove adverse health risks at low doses. However, because of the seriousness of the health risks involved, the FDA is ethically unable to study its effects at low doses in humans. It is unclear whether the ban on ephedra will remain in most markets.

Regulatory concerns regarding the quality control of supplements include:

• Standardization. Supplements are not currently required to be standardized within the United States. Thus, it is not possible to ensure precise outcomes for every product. Levels of active ingredients in supplements may vary significantly from batch to batch. The amount of active ingredient in a product may also differ, depending on manufacturer, product type and form (e.g., capsule, liquid). Until formal national guidelines can be established, supplements that currently indicate “standardized” on their label do not necessarily indicate product quality.
  
  
• Purity. Supplements may be mixed or diluted with other matter. Thus, supplements may not in fact contain the amount of active ingredient they claim to contain.

The FDA intends to issue regulations on Good Manufacturing Practices (GMP) especially for dietary supplements. This will help to ensure the identity, purity, quality, strength and composition of supplements. In the interim, manufacturers for supplements are required to abide by the GMP for foods, which are generally more concerned with hygiene and sanitation.

Supplements carrying the term USP (U.S. Pharmacopeia) have met the standards for strength, purity and the ability to dissolve the organization requires. This organization also follows safe and sanitary manufacturing procedures. People may want to choose supplements with USP on the label.

The most important questions concerning supplement use depend on a variety of factors. However, health professionals usually recommend that people receive adequate nutrients from foods instead of from supplements.

Optimal supplement usage may depend on a person’s current diet and stress levels, individual body size and tolerance levels. It may also depend on age, current health status and any temporary conditions (e.g., cold, flu). What time of day to take a supplement may depend on the type (e.g., stimulants should not be taken before bedtime, and supplements that may upset the stomach should be taken with meals).

Consumers are advised to consult their physician or a registered dietitian before using any type of supplement. Certain supplements may interfere with medications (both prescription or over-the-counter), other supplements, foods or beverages, and certain medical conditions. Lifestyle habits (e.g., smoking, alcohol use, level of physical activity) may also affect supplement use. A physician or registered dietitian may be able to offer the best advice as to which supplements may be right for a particular person.

Additional consumer advice regarding supplements includes:

• Read label carefully. Know what is contained in the supplement and what effect it has on the body before using it. This is especially true for people with allergies or food intolerances. Certain supplements may contain ingredients from potential allergens (e.g., shellfish, gluten, milk products).
  
  
• Get more information. Contact the supplement manufacturer for information on their product, such as substantiation of its product claims and product safety.
  
  
• Beware of claims that are too good to be true. Supplements cannot diagnose, treat or cure any disease. Any claims to this effect should be questioned. Supplements that promise miracle cures (e.g., lose weight without exercise or dieting) should not be believed.
  
  
• Purchase reliable brands.  Because most product claims and safety for supplements are the responsibility of the product manufacturer or distributor, purchasing reliable brand name supplements may result in a better quality product, although it is not guaranteed.
  
  
• Avoid megadose supplements. There is little evidence that more than the recommended daily value (e.g., 500 percent daily value) of nutrients provides “extra” protection against disease. In addition, high levels of nutrients may build up in the body and cause toxic effects, especially fat soluble vitamins (A,D,E,K). Consumers are advised to purchase supplements that do not contain more than 100 percent of the daily value for any one nutrient.
  
  
• Check expiration dates. Supplements, like drugs, may lose potency over time.
  
  
• Ignore “natural” or “organic” claims. Dietary ingredients in supplements may be synthesized (put together) organically (e.g., in the plant that originally contained the chemical) or inorganically (e.g., in a lab). However, no matter where the synthesis takes place, the body uses the ingredient the same way. Thus, supplements that claim to be “natural” or “organic” do not mean the product is any more safe or risk-free than inorganic supplements.
  
  
• Use appropriately. Consumers should follow directions on the supplement label, and should be careful not to overuse the product because it may be toxic in large amounts.
  
  
• Store safely. Supplements should be stored in a cool, dry place. They should also be kept out of reach of children to avoid accidental ingestion and possible overdose.
  
  
• Do not use supplements to treat a medical condition. Supplements cannot diagnose, treat or cure any disease. Consumers should consult a physician for proper diagnosis and treatment.
  
  
• Start small. Keep supplement use as simple as possible. Consumers may want to limit supplement use to two or three basic supplements – such as a multivitamin, an antioxidant (e.g., vitamin C or E) and a specialty supplement (e.g., amino acids or enzymes). Which supplements are chosen may depend on a variety of factors and should best be determined by consulting a physician or registered dietitian.  

Many experts recommend purchasing supplements produced in Germany because that country’s supplement regulations are stricter than those currently practiced in the United States.

For the most part, there are no recommended or safe dosage levels that exist for herbs and certain other non-nutrient supplements. These products have not been subjected to regulated research studies designed to determine safe or recommended amounts.

Recommended daily allowances of vitamins and minerals have been developed by the National Academy of Science, Institute of Medicine, Food and Nutrition Board. Dietary Reference Intakes are defined as reference values for planning and assessing nutrient intakes of healthy people. There are three types of these reference values:

• Recommended Daily Allowances (RDA). The average daily intake required to meet the nutritional needs for most healthy people (in specific age and gender groups).
  
  
• Adequate Intakes (AI). This value is used when an RDA cannot be established due to a lack of sufficient scientific evidence.
  
  
• Tolerable Upper Intake Levels (UL). The maximum daily intake that can be safely tolerated in most healthy people. 

Preparing questions in advance can help patients have more meaningful discussions with health professionals regarding their conditions. Patients may wish to ask their doctor or registered dietitian the following questions about supplements:

1. What types of dietary supplements should I be taking?
   
   
2. Are they safe?  What are their side effects?
   
   
3. Will these supplements interact with any of my current medications?
   
   
4. Are there certain over-the-counter medications I should avoid while taking these supplements?
   
   
5. Are there certain types of foods I should avoid while taking these supplements?
   
   
6. If I become pregnant or develop certain health conditions (e.g., high blood pressure, heart problems), should I discontinue use of certain supplements? Which ones?
   
   
7. If I’m scheduled for surgery, which supplements should I stop taking prior to surgery? How long before surgery should I stop taking them?
   
   
8. How long should I take these supplements?
   
   
9. Is it possible to overdose on these supplements? What amount is appropriate for me?
   
   
10. What types of symptoms that I experience while taking these supplements should I report to you?