An important article in the May 19, 2017 New York Times discusses the latest accusations that some of America’s top athletes are using supplements, both legal and illegal, in the hope that they will improve athletic performance. I will present a brief review of some of the supplements that the accused U.S. athletes are taking and comment on their effectiveness or worthlessness, side effects and potential dangers to their health.

High Doses of Vitamin D
No good data show that large doses of vitamin D improve performance in athletes who are exposed to sunlight regularly (Curr Opin Clin Nutr Metab Care, Nov 2014;17(6):539-45). Large doses of Vitamin D do not strengthen bones in athletes who have normal blood levels of hydroxy vitamin D (>30 ng/mL). However, vitamin D receptors are found in muscles and some data show that vitamin D may decrease recovery time from intense workouts, so the athlete can take his next intense workout sooner and therefore improve muscle function (J Int Soc Sports Nutr, Aug 19, 2015;12:33). You should know that doses of vitamin D3 greater than 5000 IU/day have been reported to be associated with increased risk for kidney stones, arteriosclerosis and heart attacks.

Calcitonin is a hormone produced by your thyroid gland that acts to lower blood calcium levels by driving calcium from the blood into bones. There is some evidence that it may help strengthen bones, particularly in female athletes who stop menstruating because of their intense training, but I could find no good evidence anywhere that it improves athletic performance. High blood levels of calcitonin are associated with increased risk for thyroid cancer.

Lack of iron can cause anemia which certainly interferes with athletic performance by decreasing available oxygen for use by your muscles. Almost all the oxygen that goes to your muscles is carried by red blood cells. Iron outside your red blood cells does not carry oxygen to muscles. I could find no good evidence that having high levels of iron improves athletic performance in athletes who are not iron deficient. Fortunately, doctors have a simple test to tell if you are low on iron. Get a blood test called ferritin. If it is above 50 ng per ml, you have more iron than you need and do not need iron. You can be harmed by taking iron when you are not deficient because iron is a potent oxidant that can damage tissue.

Asthma Inhalers
Most asthmatics can benefit from using an asthma inhaler (salbutamol) prior to competition. The bronchial tubes of asthmatics can close down during exercise to decrease oxygen intake. A note from your doctor stating that you are asthmatic will allow you to take your inhaler prior to competitions legally. However, most studies show that some non-asthmatics do not appear to benefit from inhalers (Int J Sports Med. Oct, 2004;25(7):533-8). Even though an inhaler raises blood levels of free fatty acids (an energy source) at rest, it does not do so more than a placebo does during exercise. Even though asthma inhalers widened bronchial tubes at rest, they did not do so in non-asthmatics during or after exercise. Nonetheless, most Olympic swimmers have notes from their doctors that they are asthmatic and need to take inhalers before competitions.

Everyone agrees that caffeine improves athletic performance. For a while caffeine was banned in the Olympics, but it was impossible to control, because athletes with high levels claimed that they were getting the caffeine from coffee, tea, chocolate, soda, cocoa and other food sources. Now it is perfectly legal for athletes to take caffeine during competitions. Caffeine increases the use of fat to fuel your muscles to improve endurance and power, widens the bronchial tubes to let you breathe more oxygen, and even improves heart efficiency. At high doses, it can cause dizziness, insomnia, and raise blood pressure. See Caffeine Boosts Endurance and Strength

Anabolic Steroids (Testosterone – Male Hormones)
Anabolic steroids make you stronger, faster and give you greater endurance. You cannot strengthen muscles unless you damage them with an intense workout; when muscles recover, they will be stronger. All knowledgeable athletes train by taking an intense workout on one day, feel sore on the next day, and then go at a less intense pace until the soreness goes away so they can take their next intense workout. When an athlete starts taking anabolic steroids, within just a few days he notices that he recovers much faster from workouts, can do more intense workouts and becomes much stronger. Indeed, during long-term intense training, blood testosterone levels drop and a person can suffer from overtraining syndrome (Int J Sports Med, Nov 2002;23(8):555-60). However, taking anabolic steroids comes with a steep price including premature death from a heart attack.

Carnitine Injections
Carnitine is found in almost every cell in your body. It is made by your liver and kidneys from two amino acid protein building blocks and it carries fat into the mitochondria of cells where it can be used as a source of energy. Your muscles use fat and sugar as their primary sources of energy. You have enough fat stored in your body to last you for weeks, but you start to run out of your meager sugar supply stored in your liver and muscles after 70 minutes of intense exercise. Fatigue during exercise is caused by using up your meager supply of sugar.

Since carnitine carries fat into the mitochondria furnaces of your muscles, it was thought that increasing carnitine would cause muscles to burn more fat and therefore spare your meager sugar supply and give you greater endurance, but after more than 25 years of extensive research, there is no consistent evidence that carnitine pills or injections improve physical performance in healthy subjects (Ann NY Acad Sci. 2004;1033:67-78) and most studies show that carnitine pills do not increase the amount of carnitine in muscles (Am J Clin Nutr, 2000;72:618S-23S). One study shows that massive doses by intravenous infusion can raise muscle carnitine levels (J Physiol, 589.4 (2011) pp 963–973) and that sets the stage for some athletes taking massive doses of carnitine infused into their veins prior to competitions. These higher muscle levels of carnitine then force the muscle to use more fat, sparing the meager supply of sugar, which allows the athlete to exercise intensely for a longer period of time (Nutrition, 2004;20:709–715). All available data show that taking sugar sources during endurance events will give you all the sugar you need to keep on exercising. The only justification for an intravenous infusion of carnitine prior to races is that it is difficult to eat and drink a lot of sugar when you are racing. Otherwise, there is no reason for a person to have these intravenous infusions, and they are banned.

Anything that maintains blood sugar levels during exercise helps athletes to move faster, stronger and longer. Cortisone-type drugs can substantially improve athletic performance by raising blood sugar levels to prevent fatigue and prolong endurance. Athletes are prohibited from taking cortisone-type drugs in the Olympics and other competitions because cortisone-type drugs have terrible side effects. Long-term use can cause bone loss, decreased immunity, cataracts, stomach ulcers, insomnia, mood swings, personality changes, depression and more. However, athletes are allowed to take cortisone-type drugs if a doctor prescribes them to treat a medical condition. That means that, for example, an athlete can get a doctor’s note for cortisone-type drugs to treat tendon pain (tendinitis) and then win a race “legally” even if testing shows high blood levels of the drugs. See Benefits of Exercise from a Pill?

My Recommendations
Stop looking for ways to cheat to become a better athlete. The multi-billion dollar business of sports supplements drains the wallets of people who often can ill afford to waste their hard-earned money on a largely uncontrolled industry that sells products that are rarely tested for safety or efficacy.