Where do the vitamins in supplements come from?

Most vitamins are extracted from the food sources in which they naturally occur. For example, vitamin A is often extracted from fish liver oil. Vitamin B comes from yeast or liver, vitamin C from rose hips, and vitamin E from soybeans, wheatgerm or corn.

Supplements are available from many sources but most supplement manufacturers get the raw materials from the same small group of suppliers. They are then packaged and labeled before being sent to distributors or retail outlets.

What types of supplements are available?

There is a vast range of vitamin, mineral and other nutritional supplements available in supermarkets, health food stores and drugstores. Products vary widely in quality and effectiveness, and evidence to support some of the claims made by those who sell them is inconclusive at best.

Most supplement manufacturers follow good manufacturing practices, which ensure that the product contains what it says on the label; that it breaks down to a form which is available for absorption; and does not contain toxic chemicals. If in doubt, it is worth checking with the supplier. Good quality supplements are available from medical practitioners, health food stores, drugstores and supermarkets. Many experts recommend buying name brands, such as USANA Vitamins, or own brand supplements from large national stores with a reputation for quality.

Vitamin and mineral supplements come in various forms. The most common are tablets which are convenient to store and carry and have the longest shelf life. Capsules are also easy to store, but may not be as good at protecting the contents from oxidation. Enteric-coated capsules, which are also known as timed release supplements, are another form. They are designed to pass through the stomach to dissolve in the intestine. Fat soluble vitamins and other oil supplements often come in the form of gelatin capsules. Powder forms do not contain fillers, binders or additives. Liquids are suitable for people who have difficulty swallowing capsules.

Vitamin supplements contain many other substances such as fillers, binders, lubricants, disintegrators, colors, flavors and sweeteners, coating materials and drying agents. A person who is prone to allergies should check the ingredients of a particular type of supplement.

When buying supplements, it is helpful to have a clear idea of what nutrients are necessary, and in what amounts. This should be based on dietary strengths and weaknesses and particular needs. Reading the labels carefully should provide enough information to match the product with a person’s individual needs.

Supplement labeling

The US government has recently announced new rules on the labeling of dietary supplements. The new rules are designed to give consumers more complete information regarding the ingredients in dietary supplements. They apply to vitamins, minerals, herbs and amino acids. The rules require the products to be labeled as dietary supplements and to carry a ‘Supplement Facts’ panel that lists how much of the RDI of nutrients are in the product. For ingredients that have no RDI, such as herbs, the package will list the ingredients. Herbal products must identify the part of the plant used to make the substance.

Supplements could only claim to be ‘high potency’ if a nutrient is present at 100 per cent or more of the RDI. For multivitamin supplements to carry the ‘high potency’ labeling, at least two-thirds of the nutrients must be present at levels that are more than 100 per cent of the RDI.

The term, antioxidant, may be used to describe a nutrient where scientific evidence shows that if it is absorbed in sufficient quantity, the nutrient (such as vitamin C) will inactivate free radicals or prevent free radical-initiated chemical reactions in the body.

The amounts of vitamins and minerals in supplements are indicated in a number of ways:

A milligram (mg) is 1/1000th of a gram (g); there are 1000 mg in a gram.

A microgram (abbreviated mcg or mg) is 1/1000th of a milligram; there are 1,000,000 micrograms in a gram.

The international unit (IU) is an arbitrary measure used for vitamin A (and beta carotene), vitamin D and vitamin E.

Retinol equivalents (RE) are now being used to measure vitamin A (and beta carotene activity) and tocopherol equivalents (TE) to measure vitamin E. This is because vitamins A and E are found in several different forms in the body and these measurement units make it possible to compare the various forms.