The new year is a time to set new goals, and for many people this means losing weight and improving fitness. Although these goals are best met with a nutritious diet and regular physical activity, many people may turn to dietary supplements for a boost to their routines. To help cut the confusion, the Office of Dietary Supplements (ODS) at the National Institutes of Health has two new resources to help people understand what is known about the effectiveness and safety of many ingredients in dietary supplements promoted for fitness and weight loss.

Dietary Supplements for Exercise and Athletic Performance (https://ods.od.nih.gov/factsheets/list-all/ExerciseAndAthleticPerformance/) covers products -- sometimes called ergogenic aids -- that claim to improve strength or endurance, increase exercise efficiency, achieve a performance goal more quickly, and increase tolerance for more intense training.

"Dietary supplements marketed for exercise and athletic performance can't take the place of a healthy diet, but some might have value for certain types of activity," said Paul M. Coates, Ph.D., director of ODS. "Others don't seem to work, and some might even be harmful."

This fact sheet covers more than 20 ingredients found in fitness supplements, including antioxidants, beetroot, tart cherry, branched-chain amino acids, caffeine, creatine, and protein. Creatine, for example, might help with short bursts of high-intensity activity like sprinting or weight lifting, but not for endurance efforts like distance running or swimming. However, antioxidants such as vitamins C and E don't seem to improve any type of physical activity, though they're needed in small amounts for overall health.

More than two-thirds of adults in the United States are overweight or obese, and many are trying to lose those extra pounds. Dietary Supplements for Weight Loss (https://ods.od.nih.gov/factsheets/list-all/WeightLoss/) guides readers through the confusing set of options in the marketplace.

"Americans spend over $2 billion a year on dietary supplements promoted for weight loss, but there's little evidence they actually work," said Anne L. Thurn, Ph.D., director of the ODS Communications Program. "And people may not know that many manufacturers of weight-loss supplements don't conduct studies in humans to find out whether their product works and is safe."

This fact sheet covers 24 ingredients found in these products, including African mango, beta-glucans, chromium, garcinia, green tea, hoodia, and raspberry ketones. Chromium, for example, might help you lose a very small amount of weight and body fat, and is safe, but raspberry ketones haven't been studied enough to know whether they're safe or effective. And while drinking green tea is safe, taking green-tea extract pills has been linked to liver damage in some people.

Both fact sheets are available in a health professional version that is detailed and fully referenced, as well as consumer versions in both English and Spanish. In fact, most ODS fact sheets on dietary supplement ingredients are available in these multiple formats.

"We encourage people to talk with their healthcare providers to get advice about dietary supplements and to visit the ODS website to learn valuable information about these products," said Coates. "People can also sign up for the ODS listserv to be notified when we add new information to our website."