Creatine is a substance found in muscle cells that can help your muscles produce energy, particularly while lifting heavy weights or exercising intensely. Your body makes creatine from three amino acids (protein building blocks) called L-arginine, glycine, and L-methionine. You also get creatine when you eat animal protein: meat, poultry or seafood. A 160-pound person uses about two grams of creatine per day, usually with about half made by your body and half from your food. One pound of beef or salmon provides about 1-2 grams of creatine. Creatine is stored primarily in skeletal muscles, with small amounts stored in the liver, kidneys and brain.
How Creatine Supplies Energy for Muscles
Your muscles get their energy from carbohydrates, fats and protein in the presence of oxygen. However, when you exercise so intensely that you can’t get all the oxygen you need to burn food for energy, your muscles can get their energy without oxygen from ATP (adenosine tri phosphate), also called A3P. Your muscle removes a phosphate from ATP (A3Phosphate) to form ADP (A2Phosphate) to supply energy. ADP offers no energy for cells, so your body uses creatine to supply a phosphate molecule to convert ADP (no power) back to ATP (a source of power that doesn’t need oxygen). If you increase the supply of creatine, theoretically you could have more phosphate to convert ADP (A2P) to ATP (A3P) and thus have more energy to lift heavier weights. However, studies of this are very contradictory.
North Americans spend more than 2.7 billion dollars a year on sports supplements, of which creatine is the most common. Creatine pills and powders will help you to become stronger only if you also do heavy resistance exercises at the same time (J Int Soc Sports Nutr, 2012; 9: 33). Taking creatine supplements will not help you to run faster (International Journal of Sport Nutrition and Exercise Metabolism, 2017;27(3):285–292) or help to control weight (Human Kinetics Journals, 2017;27(3):285-292). Creatine offers no benefit in preventing muscle injuries or cramps (Sci Sports Exerc, 2001;33(2):183–188).
There are several different forms of creatine. Since we have cumulative data only on creatine monohydrate, you may be risking your health if you take other forms of creatine that have not been studied.
The studies we have show that creatine is possibly safe taken in doses of up to 5 grams daily for up to 18 months (J Sprts Med, 2017;8:213-226), and possibly safe taken in doses up to 10 grams daily for up to five years (Sports Medicine, 2015;45(9):1285-1294). It appears that doses greater than 20 grams per day offer no additional muscle benefits. These high doses may harm you by causing:
• stomach pain, nausea, diarrhea, or muscle cramping
• weight gain by causing muscles to retain extra fluid (Journal of Athletic Training, Jan 2003;38(1):44–50)
• increased risk for kidney problems, particularly if you have high blood pressure or diabetes, or take non-steroidal anti-inflammatory drugs (NSAID) such as ibuprofen
The chemical process of extracting creatine in the laboratory forms toxic contaminants called dicyandiamide and dihydrotriazines, that have to be removed before humans can take them safely. The industry that distributes creatine is unregulated and you have no way to know what you are actually buying.
Creatine supplements will not help you grow larger or stronger muscles unless you also do heavy resistance exercises. Creatine can enlarge muscles without increasing strength by causing them to retain more water.
If you decide to take creatine supplements, make sure you have healthy kidneys and do not have heart disease, liver disease or diabetes, do not take NSAID pain medicines, and are not pregnant.
I believe that you should never exceed five grams per day of creatine supplements. Since you have no way to know what you are actually getting in creatine supplements, I think that the best sources of creatine are fish or chicken.