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Can you benefit from taking a dietary supplement?

Athletes with less than optimal nutritional status compromise their physical performance. Athletes face several barriers to good nutrition--lack of nutrition knowledge, dietary extremism, poor practical skills in choosing or preparing meals, a busy lifestyle, and frequent travel. Nutrition plays a very important part in athletic performance, yet many active people fail to consume a diet that helps them perform at their optimum level. The first and most important modification an athlete must make to his or her diet to ensure optimal performance is to increase the energy intake in proportion to the energy used. Athletes also require more water, protein, vitamins and minerals (especially iron and calcium). To fulfill the extra nutritional requirements, athletes may turn to dietary supplements such as vitamin, mineral, protein and carbohydrate supplements. Before you stock up on these expensive dietary aids however, remember that it is cheaper and easier to just eat more food.

Ergogenic Aids

A substance used by an athlete to improve performance is called an ergogenic aid. Athletes have used ergogenic aids since ancient times. Ancient Greek Olympians ate mushrooms to increase their chances to win the laurel wreath and Aztec athletes ate human hearts. Nowadays the ergogenic aid industry is massive, and almost all sporting magazines contain advertisements for new "revolutionary" ergogenic aids. The world of sports is a competitive business. Athletes fear that others are taking something that will give them an advantage. This means that many athletes will try out new substances on the off chance that it will give them the edge over other competitors. Forgotten in the push to excel are the unknown dangers of unproven substances and the temptations for misuse and abuse. Supplements can be harmful as well as useful.

Supplements that may used by athletes as an ergogenic include: 

Source: Ahrendt DM. Ergogenic aids: Counseling the athlete. American Family Physician. 2001;63:913-22.

For more information on ergogenic aids, go to American Family Physician.

Caution!
Because of the lack of regulation with dietary supplements, athletes run the risk of consuming a dietary supplement that is contaminated. Ephedra (ephedrine) is one such contaminant that can be found in a number of dietary supplements. In addition, steroid contamination, such as anandrolone and testosterone, have been documented. An athlete WILL test positive for drug use if they consume a dietary supplement containing ephedra or steroids such as anandrolone and testosterone. Visit the Gatorade Sport Science Institute for more information.

Antioxidants

Exercise can have two detrimental effects on the body. First, the increased oxygen use by working muscles increases the amount of reactive forms of oxygen known as free-radicals. A growing amount of evidence indicates that free radicals cause skeletal muscle damage and inflammation during exercise [1]. People who exercise frequently and intensely should ensure that their consumption of antioxidants is sufficient to reduce recovery time[2]. This may be done with generous servings of fruits and vegetables or with dietary supplements. To prevent cell damage from free-radicals, antioxidants act by "mopping" them up. The traditional dietary antioxidants that inhibit free-radical damage are:

Vitamin E, Alpha tocopherol or tocopherol
Vitamin C or ascorbic acid
Vitamin A, Beta carotene or carotenoids

1. Sjödin B; Hellsten Westing Y; Apple FS: Biochemical mechanisms for oxygen free radical formation during exercise. Sports Med, 1990 Oct, 10:4, 236-54.

2. Goldfarb AH: Nutritional antioxidants as therapeutic and preventive modalities in exercise-induced muscle damage. Can J Appl Physiol, 1999 Jun, 24:3, 249-66.

Supplements for those wishing to lose weight

The thought of taking a pill to lose weight will never fail to attract interest. Many supplement manufacturing companies sell products that claim to be able to do this by "stimulating metabolism" or "blocking fat digestion." A review of the scientific studies turns up no solid evidence for the long term effectiveness of these products.

Two over-the-counter dietary supplements that are promoted to accelerate metabolism with subsequent weight loss have been labeled dangerous by the FDA. These two products are Ephedra (also known as Ma Huang, Ephedra sinica or Chinese ephedra), and Phenylpropanolamine.

In addition, other commonly used weight loss supplements like Cola acuminata, dwarf elder, Yohimbine, and Garcinia camborgia are either lacking controlled clinical trials, or in the case of the last two supplements, were shown in clinical trials to be ineffective (Garcinia was successful in trials as part of a mixture with other substances. It is unclear, however, if Garcinia itself was effective). The FDA also states that the safety of these weight loss supplements is currently unknown. With the increased marketing and use of these products, FDA has received an increasing number of reports of adverse reactions associated with their use including:

* Nervousness
* Dizziness
* Tremors
* Alterations in blood pressure or heart rate
* Headache
* Gastrointestinal distress
* Chest pain
* Myocardial infarction (heart attack)
* Hepatitis
* Stroke
* Seizures
* Psychosis
* Death

These adverse reactions have been reported both in young, healthy individuals and persons with confounding or complicating conditions such as high blood pressure. In addition, a stimulant "overdose" syndrome has been reported in children and teenagers who have used these products.

Related weight-loss products often marketed as "dieters" or "slimming teas" contain a variety of strong botanical laxatives and diuretics such as Cassia species (senna) and Cascara sagada. Adverse reactions associated with these products that have been reported to FDA are typically characteristic of those seen in laxative abuse. These include severe electrolyte imbalances leading to heart problems and even death.

The FDA is concerned about the seriousness of these reported adverse events and their increasing number. Because these weight loss products are commonly marketed as dietary supplements, there is no pre-market review by FDA of their safety or effectiveness, no reliable dosing information, and no monitoring advice.

Older Adults (65+)

Older adults (65+) are at an increased risk for poor nutrition.

Undernutrition in older adults can lead to loss of muscle protein and deficiencies of vitamins B-6, B-12, D and E as well as calcium, folate and magnesium. These nutritional inadequacies can lead to the following:

• Lethargy and weakness

• Reduced bone density leading to weak, brittle bones and painful disabling fractures

• Nervous system dysfunction

• Delayed wound healing

• Inability to carry out normal activities of daily living

Recommendations for the older adult

An adequate and balanced diet is without a doubt the best way to ensure adequate nutrition. However, much scientific evidence suggests that complementing the diet with a daily multivitamin-and-mineral supplement is a sensible precaution to help avoid nutrient deficiencies that are common in older adults.

Choose a supplement with very little or no iron. Iron needs of older adults are low, and excess iron increases the risk of developing cancer and heart disease.

In addition, look for a supplement that has no more than 100% of the RDA or DRI for vitamin A. With age, vitamin A is absorbed and retained more efficiently. The potential for vitamin A toxicity is therefore greater than at a younger age. Vitamin A toxicity is a serious matter, leading to such health problems as headache, vomiting, bone abnormalities, and liver damage.

Choose a dietary supplement that DOES NOT contain:

Many vitamin and mineral supplements are aimed at the older adult. Read the labels and decide with the above warnings in mind.

If you are thinking about taking single nutrient supplements, only calcium and vitamin D have been specifically recommended for older adults. If you have any doubt whatsoever, visit your physician and get an individualized dietary assessment before taking supplements.

If you are currently taking any medication, be sure to discuss with your physician what supplements you can take. Many drugs interact with dietary supplements. Some supplements can prevent drugs from working. Other supplements can intensify drug effects to dangerous levels. Your physician and pharmacist will be able to provide more information.

Pregnant or planning on getting pregnant

Pregnant women must consider both their own requirements and the requirements of the baby. Vitamins and minerals are needed during pregnancy for the maintenance of the mother's health, to support the developing infant's growth, and to help prevent developmental defects.

Supplements to Consider:

• Folic Acid: Scientific studies show that the risk of recurrent neural-tube defects is decreased in women who take folic acid before conception and during the first 6 weeks of pregnancy [1]. A standard vitamin and mineral supplement will provide adequate folate to reduce the risk of this birth defect.

• Iron: During pregnancy, iron stores become low due to increased iron need for the fetus. The need is particularly great during the last trimester [2].

• Zinc: Zinc supplementation significantly reduces the incidence of low birth-weight babies. In addition, most measurements of labor and fetal health were better in women who took modest zinc supplements.

• Calcium: Calcium and phosphorus are vital to the structure of bones and teeth. In the last trimester of pregnancy, skeletal growth is highest and the fetus draws calcium directly from the mother's stores. In addition, clinical trials have shown that adequate calcium during pregnancy lowers blood pressure and may reduce the incidence of premature births [3].

• A simple multivitamin/mineral supplement is recommended for pregnant women who do not ordinarily consume an adequate diet and for women in high-risk categories, such as multifetal gestation, cigarette smokers, and alcohol and drug abusers [4].

 

Recommendations for Pregnancy

During pregnancy, some women can especially benefit from certain nutrients. In general, these would all be contained in a prenatal multivitamin/mineral supplement.  Those requiring vitamin and mineral supplementation in addition to a prenatal supplement include:

• Vegetarians may need supplemental vitamin B12 and zinc.

• Women carrying twins, taking seizure medication, or who have sickle cell anemia could benefit from  additional folate.

• Women who do not use dairy products and/or do not get enough sunlight would benefit from additional vitamin D.

• Adolescents and smokers may benefit from a multivitamin/mineral supplement.

Supplementing additional nutrients other than iron and a prenatal multivitamin/mineral tablet is not only unnecessary, but can be dangerous. For example, taking mega doses of vitamin A may cause birth defects. Daily vitamin A intake in the range of 10,000 IU or more can result in defects of the fetal skeletal, urinary tract, and central nervous systems. Before taking any supplements, seek advice from your physician or a registered dietitian.

1. Czeizel AE; Dudás I: Prevention of the first occurrence of neural-tube defects by periconceptional vitamin supplementation. N Engl J Med, 1992 Dec, 327:26, 1832-5.

2. Vogt C: Iron requirements of pregnancy. Clin Issu Perinat Womens Health Nurs, 1991, 2:3, 364-7.

3. Repke JT, Villar J. Pregnancy-induced hypertension oand low birth weight: the role of calcium. Am J Clin Nutr 1991; 54(1 Suppl):237S-241S.

4. Menard MK: Vitamin and mineral supplement prior to and during pregnancy. Obstet Gynecol Clin North Am, 1997 Sep, 24:3, 479-98.

 

Vegetarians

Any restriction in the foods one would eat holds the potential for dietary inadequacies. It is through eating a wide variety of foods that we are assured of getting the wide range of nutrients humans need for good health. Dietary studies have often found that vegetarians, especially vegans, consume some vitamins and minerals at less than recommended amounts. A well-chosen vegetarian diet, on the other hand, can be entirely adequate, obviating the need for dietary supplements.

Although lacto-ovo-vegetarians have no obvious need for dietary supplements, vegans are a different story. At least one study has concluded that vegans need to increase their intake of vitamin B12, riboflavin and possibly even iodine, iron and zinc [1].

• Lacto-ovo-vegetarian
  Avoids all animal flesh (fish, chicken and red meats) yet consumes dairy products and eggs.

• Lacto-vegetarian
  Avoids all animal flesh and eggs yet consumes dairy products.

• Ovo-vegetarian
  Avoids all animal flesh and dairy products yet consumes eggs.

• Vegan
  Not only avoids all meats but also abstains from all animal products such as eggs and dairy products.

1. Reddy S, Saunders TB. Haematological studies on pre-menopausal Indian and Caucasian vegetarians compared with Caucasian omnivores. Brit J Nutrition 1990; 64: 331-338