Dietary supplement
According to US & Canadian Dietary Reference Intake guidelines, the protein Recommended Dietary Allowance (RDA) for adults is based on 0.8 grams protein per kilogram body weight. The recommendation is for sedentary and lightly active people. Scientific reviews can conclude that a high protein diet, when combined with exercise, will increase muscle mass and strength, or conclude the opposite. The International Olympic Committee recommends protein intake targets for both strength and endurance athletes at about 1.2-1.8 g/kg body mass per day. One review proposed a maximum daily protein intake of approximately 25% of energy requirements, i.e., approximately 2.0 to 2.5 g/kg.
Niacin
The U.S. Institute of Medicine (renamed National Academy of Medicine in 2015) updated Estimated Average Requirements (EARs) and Recommended Dietary Allowances (RDAs) for niacin in 1998. The European Food Safety Authority (EFSA) refers to the collective set of information as Dietary Reference Values (DRV), with Population Reference Intake (PRI) instead of RDA, and Average Requirement instead of EAR. AI and UL defined the same as in United States. For women (including those pregnant or lactating), men and children the PRI is 1.6 mg niacin per megajoule (MJ) of energy consumed. As the conversion is 1 MJ = 238.8 kcal, an adult consuming 2388 calories should be consuming 16 mg niacin. This is comparable to U.S. RDAs. The niacin UL is set at 10 mg/day, which is much less than the U.S. value. The UL applies to niacin as a supplement consumed as one dose, and in intended to avoid the skin flush reaction. This explains why the PRI can be higher than the UL.