Quality and number of subjects in blinded controlled clinical trials about the nutrition and dietary supplements discussed here is variable.
Glucosamine sulfate and
chondroitin sulfate have sufficient controlled trials to warrant their use in
osteoarthritis, having less side effects than currently used nonsteroidal anti-inflammatory drugs, and are the only treatment shown to prevent progression of the disease. Dietary supplements of
ephedrine plus
caffeine for
weight loss (
weight loss being the current first line recommendation of physicians for
osteoporosis) show some promise, but are not sufficient in number of study subjects.
Phenylpropanolamine is proven successful in
weight loss. Both
ephedrine and
phenylpropanolamine have resulted in deaths and hence are worrisome [table: see text] as an over-the-counter dietary supplement. 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, have clinical trials showing lack of effectiveness (although Garcinia has been successful in trials as part of a mixture with other substances, it is unclear if it was a necessary part of the mixture). Safety of these
weight loss supplements is unknown.
Chromium as a body building supplement for athletes appears to have no efficacy.
Creatine may help more in weight lifting than sprinting, but insufficient study subjects and safety information make more studies necessary.
Carbohydrate loading is used commonly before endurance competitions, but may be underused as it may be beneficial for other sport performances. Supplements for muscle injury or
cramps have had too few studies to determine efficacy. Although proper
rehydration with fluids and
electrolytes is necessary, a paucity of actual studies to maximize prophylactic treatment for exercise induced cramping still exists. Nutritional supplements for cardiovascular disorders are generally geared to prevention. The United States Department of Agriculture has good recommendations to prevent
atherosclerosis; a stricter version by Ornish was shown to reverse
coronary heart disease, and the low meat, high fruit, and vegetable
DASH diet has been found to decrease
hypertension. The epidemiologic studies of
hyperhomocysteinemia are impressive enough to give
folic acid (or
vitamin B6 or B12) supplements to those with elevated
homocysteine levels and test patients who have a history of atherosclerotic disease, but no controlled clinical trials have been completed. Soluble fiber has several positive studies in reduction of
cholesterol levels and generally is accepted. The data on
vitamin E are the most confusing. This
vitamin was not helpful in cerebrovascular prevention in China and not helpful at relatively small doses (50 mg) in the United States or Finland against major coronary events. Levels of 400 mg appeared to decrease
cardiovascular disease in the United States in studies based on reports by patients and in one large clinical trial.
Vitamin E also was successful in prevention of restenosis after PTCA in one clinical trial. Both of these clinical trials need to be repeated in other developed country populations. Some nutritional and dietary supplements are justifiably useful at this point in time. Several meet the criteria of a late Phase 3 FDA clinical trial (where it would be released for public use), but many dietary supplements have insufficient numbers of studies. Some deaths also have occurred with some supplements. If these supplements were required to undergo clinical trials necessary for a new
drug by the FDA, they would not be released yet to the public. Several nontoxic supplements appear promising, though need further study. Because they have essentially no toxicity (such as
folic acid with B12, soluble fiber, and
vitamin E) and may have efficacy, some of these supplementations may be useful now, without randomized clinical trials.