Don’t assume more treatment is better.
Many health actions that are helpful also have harms. Increasing the dose or amount of a treatment can increase harms without increasing beneficial effects.
Explanation
It is common that health actions have unwanted effects. Sometimes, these unwanted effects (also called side effects or harms) can be serious. Research has shown that about three-quarters of reported unwanted effects are related to the dose or amount of the treatment.
Example
Millions of people take dietary supplements hoping to maintain or improve their health. These include vitamins, minerals, amino acids, and other substances. Sales of dietary supplements exceeded $30 billion in the U.S. alone in 2011. However, fair comparisons have not detected beneficial effects in healthy people. In fact, some fair comparisons suggest that routine and high-dose supplementation may not be safe.

Remember: If something we do for our health (a health action) is believed to be beneficial, do not assume that more of it is better.
- Book: More is not necessarily better. In: Testing Treatments.
- Video: Bohemian Polypharmacy. This is a parody by James McCormack lasting 6:45 minutes.
- Video: Do vitamin supplements really work? This is a Reactions video lasting 4:48 minutes.
- Video: Do supplemental vitamins actually work? This is a BrainStuff video lasting 5:16 minutes.
- Video: The disturbing truth about vitamin supplements – sharp science This is a Mashable video lasting 5:11 minutes.
- Video: Are multivitamins a waste of money? This is a PictureFit video lasting 6:05 minutes.
- Blog: More is not necessarily better. Students 4 Best Evidence.