I am concerned with the indiscriminant use of products like MET-Rx due to the potential for intake of toxic levels of some nutrients, not to mention very un-balanced diets. My major concerns are that only 4 packets of MET-Rx provide:

• 1040 kcal.
• Over two times the RDA [recommended daily allowance] for protein for most individuals. Chronic high protein intake may have some adverse effects. Many people are experimenting on themselves, so maybe we will have a better idea when they get to premature kidney failure age.
• 160% of RDA for vitamin A (as retinol). Higher intakes could definitely be dangerous for women at conception or in early pregnancy.
• No fiber.
• About five times the RDA for adults of vitamin D. These levels of intake can be dangerous if consumed chronically according to the RDA manual.
• 2800 mg of calcium. Experts recommend no more than 2000 mg/day. Higher amounts may have adverse effects on bone remodeling rate.
• 29 mg of iron. This level can be dangerous for men and post-menopausal females, especially if they are genetically predisposed to hemocratosis (iron overload disease).
• 24 mg of zinc. Zinc consumed at this or higher levels can interfere with copper utilization (see the RDA manual).

Implication. Use MET-Rx and similar products only in moderation and with care and good sense. Athletes should not indulge these supplements without the advice of a physician or registered dietitian. A natural varied diet can provide the essential nutrients needed for athletic performance.

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