Science of supplements

Taking the right supplements can be beneficial to your health, but they’re not without risk. “Natural” does not always mean “safe”. For example, the herbs comfrey and kava can cause serious harm to your liver. So, never take any supplement without first talking to your doctor.

What you need to know

The “science” behind supplements is not always clear. For example, a growing body of evidence suggests that multivitamins offer few or no health benefits, and some studies suggest that high doses of certain vitamins may even cause harm. As the dosage is not always scientifically determined, overdosing can be a problem. For example, an overdose of vitamin A is toxic to the liver and may lead to serious consequences. High doses of water soluble vitamin C are not much use as 76% is excreted by the kidneys!

There’s no clear regulation on supplements in South Africa. Supplement companies do not need to test and prove that their products are effective, pure and safe before they’re put on the market. Supplement manufacturers may mention “scientific” evidence, but the evidence may be insufficient, irrelevant, misinterpreted or even fabricated.

Therefore, be aware that:

• • Products sold as “nutritional supplements” (including sports supplements) can be advertised and sold with misleading claims, incorrect labelling, and no scientific proof that they’re safe.

• • Herbal supplements may not contain the correct plant species.

• • Supplements may contain more or less ingredients than the label states. That means you may be taking less or more of the supplement than you realise.

• • The supplement may be contaminated with other herbs, pesticides, metals, or even contain illegal ingredients such as prescription medication.

• • Most dietary supplements have not been tested in pregnant women, nursing mothers, or children.

Advantages

In certain conditions or situations supplements may have advantages. For example:

• • Vegetarians may find a vitamin B12 supplement (naturally present in meat and eggs) helpful.

• • If you’re allergic to milk and milk products, you may need a calcium supplement.

• • If you don’t consume certain foods such as fish or walnuts that contain omega 3 fatty acids, you may need this supplement, which is beneficial to the brain.

• • A specific type of folic acid taken during pregnancy can help reduce the risks of a baby developing birth defects.

• • HIV-positive people could take multivitamins to boost immunity and slow the progression of the disease.

Talk to your doctor

If you take any medications (whether prescription or over-the-counter) you should discuss supplementation with your doctor. Some dietary supplements can interact with medications. For example, vitamin D lowers the blood levels of certain cholesterol lowering medications and St. John’s wort makes many medications less effective.

Before having surgery tell the doctor about your supplements. Certain dietary supplements may increase the risk of bleeding or affect your response to anaesthesia.

“People most likely to take supplements are those who least need them. It may be doing no good, and could be harmful. If you eat well, you don’t need supplements”, according to Susan Taylor Mayne, professor at Yale School of Public Health.

 

Sources

Brenda Goodman. 2013. HealthDay News. Dec. 16.
Gary Gabriels, Mike Lambert, Pete Smith, Donavon Hiss. South African Medical Journal. Vol 101, No 8 (2011)
http://nccam.nih.gov/health/supplements/wiseuse.htm
www.dsld.nlm.nih.gov/dsld/
www.mdhil.com
www.scientificamerican.com