While reading a new Danish study about cheese and heart disease, I found myself getting a little angry! The headline declares “When Choosing Cheese, Low Fat May Not Matter.”
I thought, ‘This looks interesting,’ and I continued reading, looking for keys about whether or not this is a study worth noting. The more I read, I was reminded of the many ways studies can be flawed. In fact, it provided so many examples of poor design, I thought I would use it to offer a guideline for what to watch out for when reading nutrition news in the media.
- Watch for studies with funding sources that could be a conflict of interest. In the case of this study, funding was provided by the dairy industry of Denmark and other countries, raising some question about self-interest.
- Use a critical eye to notice any glaring study design components that don’t seem logical. The control group in the Danish study did not sound like the neutral “no treatment” group it should have been to allow for valid comparisons with the treatment groups. The controls had part of their diet replaced with bread and jam. The other two groups had part of their diet replaced with low fat cheese and full fat cheese. The intent of the study was to compare the effect of low fat cheese to full fat cheese, with the control group representing a supposedly neutral effect. The problem is that there are several good studies that show negative effects on heart health from a low fat diet containing higher amounts of processed carbohydrates and sugar, as in . . . you guessed it – bread and jam. Hardly neutral!
- The number of participants matters! This study used 139 volunteers, which may or may not have been large enough to draw a valid conclusion for larger groups of people. Larger numbers are always more dependable.
- The length of the study matters! In this case, the study ran for 12 weeks. That may have been long enough to see changes in the blood levels of the values they were tracking, which has some value, but the long term effect on heart health cannot be determined in 12 weeks.
- Truly good nutrition studies are difficult to do on human subjects, because control of actual behavior is usually very limited. When allowed to live freely in their own environments outside of a lab, researchers usually must depend on self-reported adherence to diet standards. This is understandable, because it is prohibitively expensive to study large groups of people for long periods of time while being constantly observed.
It may be absolutely true that it makes no health difference whether you eat full fat cheese or low fat cheese. That is not the point I am trying to make. I am merely pointing out the potential flaws in nutrition research to look out for.
I am not saying that nutrition research is not worth doing unless it holds up to gold standards of practice. Good research is always valuable. It is simply important to keep in mind whether a study is a little flawed or flawed to the point of being useless.
I also like to remind others as well as myself that we are all unique individuals, and studies are performed on a select group of people. Even when studies are well designed and performed, results are only truly representative of the group examined. You may be one of the less common outliers. Ask yourself if the results make sense and would work well for you.