Check intake against RDA percentages.
Label percentages are printed against one serving and against a generic reference population, so they rarely describe what you actually ate. Multiplying the per-serving amount by the servings consumed and dividing by your own reference value fixes both problems. The second percentage matters just as much: for nutrients with a tolerable upper intake level — vitamin A, vitamin D, niacin, selenium, iron, zinc — a very high RDA percentage from supplements can approach a level that causes harm.
Intake against reference values
Consumed = per serving x servings; RDA share = consumed / RDA x 100; upper limit share = consumed / UL x 100
These figures are population-average estimates for general planning only and are not medical or dietetic advice. Individual energy and nutrient needs vary widely with body composition, activity, medication and health status. Consult a qualified health professional or registered dietitian before making significant changes to what you eat, and especially if you are pregnant or breastfeeding, are under 18, or have a medical condition or a history of disordered eating.
Labels use a single reference value for the whole population — often the highest adult requirement — and assume exactly one serving. Your own requirement varies with age, sex and pregnancy, and you rarely eat exactly one serving.
Usually not. The RDA is set to cover nearly everyone's needs, so modest excess is harmless for most water-soluble nutrients. The figure to watch is the upper limit share, which is where genuine toxicity risk starts.
Vitamin A (3000 mcg retinol), vitamin D (100 mcg), niacin (35 mg), vitamin B6 (100 mg), folic acid (1000 mcg), iron (45 mg), zinc (40 mg) and selenium (400 mcg) are the ones most commonly exceeded through supplementation.