Source: U.S. Department of Health & Human Services, National Institutes of Health, Office of Dietary Supplements (2017).

Arginine is an amino acid in foods that contain protein, like meat, poultry, fish, eggs, dairy products, and legumes. A nutritious diet supplies about 4 to 5 grams a day. Supplement sellers claim that taking larger amounts of arginine in supplements improves performance, partly because the body converts it into nitric oxide, which expands blood vessels and increases blood flow. Increased blood flow helps deliver oxygen and nutrients to exercising muscle and speeds up the removal of waste products that cause muscle fatigue.

DOES IT WORK? Although the research is limited, arginine supplements seem to have little to no effect on strengthening and muscle-building exercises (like bodybuilding) or aerobic activities (like running and cycling). Studies have used 2 to 20 grams a day of arginine for up to 3 months.
IS IT SAFE? Arginine supplements seem safe when users take up to 9 grams a day for several days or weeks. Taking more can cause GI discomfort and can slightly lower blood pressure.
BOTTOM LINE There’s little scientific evidence to support taking arginine supplements to increase strength, improve performance, or help tired and sore muscles recover after exercise.
REMARK Many performance supplements in the marketplace contain more than one ingredient, and ingredients can work differently when they’re combined. Because most ingredient combinations have not been studied, it is not known how effective or safe they are in improving performance.

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