Dietary supplements: More is not necessarily better

The use of dietary supplements among adults in the United States has increased, according to a report from the Centers for Disease Control. Multivitamins and multiminerals are the most commonly used dietary supplements that include herbals and botanicals, amino acids, enzymes, and specialty products such as fish oils, glucosamine, and probiotics. Studies have shown that healthy adults who take dietary supplements are often more active, more highly educated, and are nonsmokers.

 

As defined by the U.S. Congress in the Dietary Supplement Health and Education Act, which became law in 1994, a dietary supplement is a product (other than tobacco) that is intended to supplement the diet; contains one or more dietary ingredients (including vitamins, minerals, herbs or other botanicals, amino acids, and other substances) or their constituents; is intended to be taken by mouth as a pill, capsule, tablet, or liquid; and is labeled on the front panel as being a dietary supplement.

 

The use of dietary supplements among members of the U.S. Armed Forces has been studied as well.  One study found higher use of performance-enhancing dietary supplements, in particular, protein and amino acid supplements among active duty military personnel compared to civilians. Performance-enhancing supplements are defined as any combination of protein, carbohydrates, fats, vitamins, and minerals taken to improve athletic performance. For active duty soldiers, the most common reasons for taking dietary supplements were to promote general well-being, boost energy levels, improve performance, and bolster gains in strength. In addition to performance-enhancing supplements, bodybuilding supplements, weight loss products and joint health products are popular among active duty military.

 

While some supplements provide the essential nutrients recommended for optimal functioning, they are not to take the place of a nutritious variety of food that are important for a healthy and balanced diet. Promotional (marketing or advertisements) materials may claim that calcium and vitamin D can reduce bone loss; folic acid prevents certain birth defects; and omega-3 fatty acids may provide a level of prevention for people with heart disease. It is important to know, however, that the U.S Food and Drug Administration (FDA) does not determine the efficacy and safety of dietary supplements before they are made available in the market.

 

A number of dietary supplements contain ingredients that can have unexpected side effects or interactions with other drugs. Here are a few examples of products that interact with other prescription drugs:

  • Vitamin K is being marketed as an over the counter supplement to promote a health heart and vascular system. Vitamin K, however, can reduce the efficacy of warfarin (Coumadin®), an agent prescribed for patients with an increased risk for heart attack, stroke and blood clots.

  • Ginkgo biloba, a popular herbal supplement, and vitamin E can interact with the blood-thinning agents, warfarin and aspirin, and when taken concurrently, can raise the risk for bleeding.

  • St. John’s wort, a widely available supplement used for depression, premenopausal symptoms, and sleep disturbances, among many others, can increase the metabolism of many other prescription drugs resulting to reduced effectiveness.

Given the amount of information available and the inconsistencies noted in various reports, it is highly recommended that the use of dietary supplements be communicated to healthcare professionals as part of an annual physical examination and health maintenance visit.

 

Here are some practical tips on the use of dietary supplements:

  • Some ingredients are added to a growing number of processed food, including cereals and smoothies. You may already be receiving more than your recommended daily allowance for these supplements. Some supplements may not be harmful when taken in excessive quantities but may cause unnecessary expense. Some agents have unwanted side effects, such as nausea and vomiting in iron overload (many products are fortified with iron).

  • Don’t take dietary supplements in place of, or in combination with medication prescribed for certain conditions without your healthcare provider’s approval.

  • Always let your health care provider know prescription drugs and over-the-counter drugs and supplements before any type of surgical procedure.

  • “Natural” doesn’t always mean safe. There are many ingredients in nature that may cause unwanted effects when metabolized or when combined with other agents.