Units of measure and other terminology pertaining to nutritional supplements are sometimes confusing.
Most vitamins and minerals are measured in milligrams (mg.) or micrograms (mcg.). These are measurements of weight that are based on the metric system. A milligram is one thousandth of a gram and a microgram is one thousandth of a milligram.
For some perspective on this, consider that it takes 28.35 grams to make an ounce and 16 ounces make a pound.
The point I want to convey here is that milligrams and micrograms are extremely small amounts. For the body to function properly, these small amounts of essential vitamins and nutrients must be present or symptoms of deficiency (illness) results.
When reading labels of nutritional supplements, you will see milligrams and micrograms for water soluble vitamins B & C, essential minerals, herbs and other substances such as omega 3 oils, glucosamine, etc. When looking at the oil soluble vitamins A, D, and E, you will see International Units (I.U.).
International Units are a qualitative measurement that is equal to the amount of a substance that is needed to produce a specific biological result. Because I.U. is a measurement of potential activity, it does not readily convert to weight based units discussed above.
Another helpful fact about nutritional supplements is that they are generally formulated for a 150 pound adult. Children’s products tend to have weight or age specific designations since the weight range for children is assumed to be greater than that of adults.
A simple proration by weight is sometimes helpful in determining how much to take. For example, a 100 pound adult would take two thirds of the recommended dosage since their weight is only two thirds that of an average 150 pound adult.
Another confusing issue about vitamin labels is the references to RDA and DV. RDA’s or Recommended Dietary Allowances were set by the government in 1941 to be the amount of essential nutrients that are necessary to meet nutritional needs of most healthy persons. The objective of the RDA’s is to state a minimum level necessary to prevent deficiency. Daily Values, or DV are an update of the old concept of RDA’s.
The primary issue with RDA’s and DV’s is that the levels are set to prevent deficiency rather than to promote optimum health. Many vitamin companies put several times the RDA or DV in their pills because their research shows that more of certain nutrients is better.
Another reason large amounts are put into supplements is that the absorption rates are sometimes extremely low. There is a vast difference between the absorption rate of a mass marketed supplement that is usually full of synthetic ingredients and fillers and the absorption rate of a high quality supplement with food based nutrients.
Margaret Durst owns The Green House, a vitamin, herb and health food store in Mason, Texas. www.thegreenhouse.myshopify.com