The Asthma Center

Nutritional/dietary supplements

Vitamins and minerals in doses larger than daily allowances have been suggested to improve natural body defense against many illnesses. Such treatments are often used for colds. They may also prevent acute sinusitis. These products include zinc and Vitamin C. Zinc is available as a lozenge, nasal gel, or pill. Studies on zinc in reducing infection length have varied. Some studies have shown zinc’s benefit. Others have found zinc has no effects on infection length. Zinc should be taken according to a recommended dosing regime. Excessive amounts of zinc can lead to nausea and vomiting. It can also affect serum high density lipoprotein (HDL) and cholesterol levels. Vitamin C, although widely taken for common colds, has not been scientifically proven to prevent them. It is possible that larger doses could reduce the duration of symptoms. However diarrhea, nausea and vomiting may also occur with large doses. A recent study reported subjects on 800mg/day of Vitamin E had less nasal symptoms compared to placebo. Vitamin E supplements may have some value in some individuals with seasonal allergic rhinitis, but more work needs to be done to confirm this observation.

Nutritional supplements including vitamins, minerals, herbs and other compounds are not regulated by the federal government. This is different than prescription medications where manufacturers must meet strict standards by the FDA for safety, efficiency and quality of manufacturing. With unregulated supplements, the products may or may not contain what is claimed on the label and may contain impurities.

The nongovernmental, nonprofit organization known as U.S. Pharmacopeia (USP) is a well respected and recognized agency that sets quality standards for pharmaceutical products. Recently USP has started a Dietary Supplement Verification Program (DSVP). This program signifies that a dietary supplement has undergone vigorous independent tests by the USP. The DSVP mark on a supplemental bottle assures consumers that the product contains the ingredients at the stated strengths and has been tested for purity and disintegration properties. It also verifies that products are manufactured in sanitary environments. This program only certifies products that are legally marketed in the United States. Post marketing assessments ensure that manufacturers continue to follow USP manufacturing guidelines. The DSVP mark, however, does not mean that the product is safe or has a health benefit.

Two other private organizations have certification programs for nutritional supplements. The best known is ConsumerLab buys products through various sources (retail stores, internet, marketing companies) and does independent testing on the products. Tests are done for ingredients, strength, contamination and dissolubility. A product passing the test may display a label – CL “Approved Product Quality” Seal. The National Sanitation Foundation (NSF) International – known for testing water products – also tests dietary supplements. Testing is done by NSF labs, and products will display the NSF mark.