Supplements are many and varied. The study listed protein powders, sports bars, and creatine, among others. Some workout supplements may be aimed at benefiting people with specific goals — like running a marathon or boosting muscle mass — or those dealing with joint pain, says Nicole Avena, PhD, an assistant professor of neuroscience at the Mount Sinai School of Medicine in New York City and a visiting professor of health psychology at Princeton University in New Jersey. According to the National Institutes of Health’s Office of Dietary Supplements (ODS), supplements are designed to improve performance, reduce the risk of injury, and enhance recovery. And while some supplements may live up to those promises, it’s important to remember the message right there in their name: Their purpose is to supplement, not substitute for, a food-forward diet. “They are never meant to totally replace anything,” says Albert Matheny, RD, CSCS, a cofounder of SoHo Strength Lab in New York City. “Your goal should be to get what you need for optimal health through your normal diet, but supplements are a good way to address a deficiency.” A primary care provider can help you identify nutrient deficiencies, per Rush University Medical Center. In other words, start with a healthy, balanced diet and consider adding supplements on top of, rather than in place of, whole foods. “If you can choose between a nice piece of fish or a protein shake, I’m going to tell you to have a good piece of fish,” Matheny says. “[Because in addition to protein], you’re going to get other nutrients as well.” If you decide to go the supplement route, be sure to choose carefully, Dr. Avena says, since the U.S. Food and Drug Administration (FDA) does not regulate them in the same way it does prescription drugs. Look for a reputable product that’s been on the market for a period of years, and make sure it’s been third-party tested, Avena suggests. If it’s been tested, you’ll likely easily find the third party’s logo on the bottle — look for those from the United States Pharmacopeial Convention (USP) or NSF International, advises Johns Hopkins Medicine. And always talk with your doctor before starting a new supplement. They may interfere with other medications, introduce side effects if taken before surgery, or may not be safe for you to take if you have existing health conditions, says the National Institutes of Health. It’s also a good idea to approach marketing claims by supplement companies with skepticism. “There is a place for supplements, but people need to be mindful of making sure they’re doing their homework and reading the labels,” Avena says. “The unfortunate reality is that there are a lot of falsehoods out there.”

1. Creatine

What it does You may have heard of creatine — it’s one of the top three workout supplements recommended by sports scientists, says Micheil Spillane, PhD, CSCS, an assistant professor with the H.C. Drew School of Health and Human Performance at McNeese State University in Lake Charles, Louisiana. According to the Mayo Clinic, creatine is naturally found in your body’s muscles and in your brain. It may help produce energy for high-intensity exercises like sprinting, as well as lifting heavy objects. Many athletes use creatine to improve strength and gain muscle. What research and experts say A small study published in June 2020 in Nutrients found that physically active young adults who supplemented with creatine during six weeks of resistance training significantly increased their leg press, chest press, and total body strength compared with the placebo group. Another study, published in the November 2018 Nutrients, found that supplementing with creatine increased muscular strength and decreased muscle damage after four weeks of training. Most athletes’ bodies tolerate creatine well. “We have a good safety profile on creatine,” Dr. Spillane says, emphasizing that it’s one of the best-studied sports supplements. “This is something that we typically will give to anybody.” While research on the effectiveness of creatine is lacking, in Spillane’s experience, about 70 percent of people respond to the supplement. Speak with your doctor before taking creatine if you’re also taking nonsteroidal anti-inflammatory drugs (NSAIDs), caffeine, diuretics, Tagamet, drugs that affect the kidneys, or probenecid (which treats gout), per Mount Sinai. It’s generally safe to take but may lead to side effects, including weight gain, muscle strains and cramps, upset stomach, high blood pressure, liver dysfunction, and kidney damage.

2. Leucine

What it does University of Rochester Medical Center states that leucine is one of three types of branched-chain amino acids (BCAAs) and is used to fuel the skeletal muscles during exercise. Leucine’s job is to repair and build muscle, including in older adults who may need assistance maintaining muscle, and is another one of the top sports supplements recommended by experts, Spillane says. Bodybuilders and athletes who need to build strength typically use this supplement. “Leucine will activate a specific pathway in your muscle that basically makes it turn on the activation for growth and repair,” Spillane says. That said, it may not be necessary to take this supplement, because you can source leucine from your diet. It’s found in meat, fish, poultry, eggs, and milk. What research and experts say According to previous research, BCAA supplements such as leucine can help improve lean muscle mass and decrease the percentage of body fat. A small study found that among 36 men and women ages 65 to 75, participants who took a supplement containing leucine twice a day improved their lean muscle tissue and functional performance. Approach high doses with caution, however, as that can lead to low blood sugar or a disease called pellagra, notes University of Rochester Medical Center. The daily upper limit of safe intake is about .53 grams (g) per kilogram of body weight, according to previous research. Also, avoid taking if you’re pregnant or breastfeeding or have maple syrup urine disease.

3. Protein

What it does Protein offers loads of nutritional benefits, and from a fitness perspective, it’s prized for enhancing muscle growth and repair and appetite control, according to Harvard Health. Most Americans get plenty of protein from their diet, but athletes who exercise at higher volumes may want to increase their protein intake to maximize the muscle-repair benefits. That’s why some athletes supplement with plant-based protein (such as pea or rice protein) or animal-based protein (such as whey), which often comes in powder form. As powders, these supplements are easy to add to workout smoothies. What research and experts say According to the ODS, athletes need 0.5 to 0.9 g of protein per pound of body weight a day. That amount could increase during times of intense training. Taking in high amounts of protein is fine from a safety perspective (in other words, there are no health risks to overdoing it for most healthy people), but there’s no benefit to going beyond the recommended amounts, according to the ODS. The authors of a review published May 2018 in Current Nutrition Reports recommended that protein come from real food if possible, and to use supplements only if you can’t get enough via diet. Marie Spano, RD, CSCS, the Atlanta-based coauthor of Nutrition for Sport, Exercise and Health, agrees. “It’s not necessary [to supplement] if you eat enough protein through food,” she says.

4. Beta-Hydroxy Beta-Methylbutyrate (HMB)

What it does When your body breaks down leucine, HMB is created. Memorial Sloan Kettering Cancer Center says HMB prevents or slows damage to muscle cells that can occur as a result of exercise, so some exercisers take it as a supplement to aid muscle growth and improve strength and endurance. What research and experts say According to a study published in the Journal of Human Kinetics in 2019 , HMB can reduce post-exercise muscle damage and speed recovery while also improving strength. Spano says it may be particularly helpful for those recovering from an injury. “Let’s say you have a 70-year-old who broke their hip, and they’re in the hospital and on bed rest,” Spano says. “HMB will help prevent muscle breakdown because there’s a lot of muscle loss while on bed rest. But for the young, average person who’s in the gym and working out, they don’t need HMB.” Memorial Sloan Kettering Cancer Center says more research is needed to back up the potential benefits to exercisers.

5. Caffeine

What it does Yes, your daily cup of coffee can do more than jolt you awake in the morning — it may also boost your exercise performance. It’s an extremely popular workout aid: According to a review published in December 2020 in Frontiers in Sports and Active Living, three out of every four athletes (including triathletes, marathoners, tennis players, and weight lifters) consumed caffeine before or during a sports competition. There are a few ideas as to why caffeine aids performance; it may preserve muscle glycogen or interact with the nervous system in a beneficial way, according to the review. What research and experts say Research suggests caffeine is effective as a workout supplement. The Journal of the International Society of Sports Nutrition evaluated research involving caffeine in January 2021 and concluded it mainly benefits aerobic endurance when taken in doses of 3 to 6 milligrams (mg) per kilogram (kg) of body weight. Experts caution that there are risks to taking caffeine supplements in any form, however. Some supplements contain 600 to 800 mg of caffeine, “which isn’t near your upper limit, but can cause severe cardiac arrest in some people,” Spillane says. Too much caffeine can also lead to less-severe — but still concerning — side effects, such as insomnia, headaches, dizziness, and increased heart rate, per MedlinePlus. The ODS recommends curbing your caffeine intake to 500 mg per day; teens shouldn’t have more than 100 mg of caffeine a day. If you take 10,000 mg in a single dose — which is 1 tablespoon of pure caffeine powder — it can be fatal. Keep a wary eye out for caffeine products mixed with ephedra, especially if you have a heart condition, hypertension, diabetes, or thyroid disease, according to Kaiser Permanente. The combination, which may be found in weight loss and energy supplements, can increase heart rate and blood pressure.

6. Beta-Alanine

What it does Beta-alanine is an amino acid that’s produced by the liver and is also available through foods, such as meat and chicken, per a previous study. Supplementing with beta-alanine may enhance sports performance because it can prevent lactic-acid buildup generated by exercise, which contributes to soreness and fatigue. The main benefit is that “you can work out longer and recover quicker,” Spillane says. What research and experts say Spillane says there’s strong evidence supporting the effectiveness of beta-alanine. For example, a small study published in April 2018 in the Journal of the International Society of Sports Nutrition found that beta-alanine supplements taken during a five-week strength-training program led to strength gains measured by the load the 30 study participants were able to lift, as well as the number of repetitions they were able to complete, compared with their initial baseline. Spano is also a fan. “I absolutely love beta-alanine for athletes,” she says. “It can be a game changer. If you’re out there on the football field or basketball court, and you’ve got a lot of muscle fatigue, beta-alanine can help buffer fatigue so your muscles don’t feel as heavy and tired.” You may not see the benefits of taking beta-alanine immediately, Spano cautions. The researchers behind the Journal of the International Society of Sports Nutrition study noted performance improvements after participants took a 4 g to 6 g supplement daily for at least two to four weeks.

7. Sodium Bicarbonate

What it does You probably already have sodium bicarbonate in your house: It’s simply baking soda. Some gymgoers use the household staple in supplement form to improve performance. It can be found in powder or tablet form. According to ODS, sodium bicarbonate can reduce lactic-acid buildup from intense, explosive, or sustained exercise that can lead to exhaustion and reduced muscle force. What research and experts say The ODS noted sodium bicarbonate could improve performance slightly during intense, short-term activities like sprinting and intermittently intense sports such as boxing. But in some people, sodium bicarbonate either provides no benefit or hinders performance. Spillane says there’s another caveat to keep in mind: “It causes significant GI distress, which can include nausea and vomiting. Of course, experiencing those side effects during a race or game could impact your performance.” Delayed-release capsules of sodium bicarbonate may be less likely to have these side effects than when it’s directly dissolved in water and ingested, according to a small 12-participant study published in January 2019 in Sports Medicine Open. Be sure you talk to your doctor before taking baking soda, especially if you take antacids, aspirin, benzodiazepines, flecainide, iron, ketoconazole, lithium, methenamine, methotrexate, quinidine, sulfa-containing antibiotics, tetracycline, or vitamins, says MedlinePlus.