Have you been following the conversation about the results of the recent systematic review and meta-analysis published in the Annals of Internal Medicine? The authors indicated that the type of fat people eat may not be as closely related to coronary risk as previously believed. The results lead to new questions on dietary guidance that focus on the total amount of saturated or unsaturated fat in the diet, without considering how fat from different food sources, such as dairy or nuts, impact heart health.
This discussion among experts interviewed by mainstream media outlets (e.g., a blog in the New York Times, CBS news, Reuters, etc.) has been about how this study challenges long-held beliefs about fat and heart disease risk. For example, check out the NPR story and audio interview with one of the co-authors of the study and other experts in the field. This comment posted to a CBS news article expresses the frustration many people feel when science seemingly contradicts itself. As one reader put it, “ever wonder why nobody listens to scientists anymore, especially with respect to nutrition? Because no matter what they say, you can just wait a couple years, and they’ll reverse themselves.”
How do you respond when people ask for your expert opinion about evolving science or seemingly conflicting information they hear or read in the media?
Using this meta-analysis as an example, here are some considerations that may help you think through how to address questions about evolving and seemingly conflicting science:
What did the study find?
First of all, the study’s comprehensive design allowed it to estimate the cumulative impact of many studies – providing a strong testament to the body of emerging science on the role of fat in heart health.
The meta-analysis of data from 72 unique studies with over 600,000 participants from 18 countries was supported by an international research collaboration led by the University of Cambridge. The researchers looked at dietary fat consumption, biomarkers of fat intake in the blood, and fat from supplements and their association with coronary risk. Here are the key findings:
- Dietary intake and supplementation of polyunsaturated fatty acids (e.g., omega-3’s from fish and plants or omega-6’s from plants) did not significantly reduce the risk for coronary outcomes.
- Dietary intake of saturated fat had no effect on coronary outcomes.
- Higher blood levels of margaric acid, a saturated fat that reflects dairy consumption, was associated with lower coronary risk.
How do these findings fit into the whole body of science on the topic?
This outcome supports previous emerging evidence showing that higher blood levels of margaric acid were associated not only with reduced risk of coronary heart disease (Khaw et al., 2012, Warensjo et al., 2010) but also with reduced risk of type 2 diabetes (Hodge et al., 2007, Krachler et al., 2008).
How do the findings compare to current dietary guidance?
Among their recommendations for overall health and to reduce the risk of heart disease, the Dietary Guidelines and the American Heart Association call for replacement of saturated fats (from meat and full-fat dairy products) with polyunsaturated fats (from nuts, seeds, and vegetable oils). While the goal of current dietary guidance is to reduce the risk of chronic disease and promote overall health, it is important to recognize that it was developed in the context of an overweight population. Many Americans are overweight, which increases their risk for a number of health problems, not just heart disease. Thus, it is recommended that we consume foods in their lowest caloric version. For dairy, that means low fat or fat free. However, more research is needed on types of fat in foods and its relationship to health outcomes.
What are your conclusions? How will you advise clients?
As people are becoming increasingly aware of the recent conversations about the role of fat in a health-promoting diet, you can help them understand how to create a balanced, nutrient-rich meal plan that is right for them based on their weight, health and wellness goals. Some may need your help in balancing higher and lower-calorie options. It’s about how people want to “spend” their calories. Find out more here.
At the end of the day, it’s about embracing nutrition as science. As new findings are published, we learn more and make adjustments along the way. That’s why the Dietary Guidelines are reviewed, updated if necessary, and published every 5 years — it is a science-based process, which continues to evolve. And continued research will lead to better ways to help people stay healthy.