Scientists still have much to learn even about common vitamins. One recent study found unexpected evidence about vitamin E. Earlier research suggested that men who took vitamin E supplements might have a lower risk of developing prostate cancer. “But much to our surprise, a large NIH-funded clinical trial of more than 29,000 men found that taking supplements of vitamin E actually raised—not reduced—their risk of this disease,” says Dr. Paul M. Coates, director of NIH’s Office of Dietary Supplements. That’s why it’s important to conduct clinical studies of supplements to confirm their effects.
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.
Don’t fear the fats! Healthy fats provide the structural component to many cell membranes which are essential for cellular development and carrying various messages (hormones) through our body quickly. Protein is also responsible for hormone production, so it’s important for women to get foods that will provide you with healthy fats and protein. Women’s cycles can also deplete your body of B vitamins, iron, zinc, and magnesium so you should be aware of your whole food intake and possibly choose to supplement (see above for more if it’s right for you).
For example, while increased consumption of fruits and vegetables are related to decreases in mortality, cardiovascular diseases and cancers, supplementation with key factors found in fruits and vegetable, like antioxidants, vitamins, or minerals, do not help and some have been found to be harmful in some cases. In general as of 2016, robust clinical data is lacking, that shows that any kind of dietary supplementation does more good than harm for people who are healthy and eating a reasonable diet but there is clear data showing that dietary pattern and lifestyle choices are associated with health outcomes.