This past quarter I took a class called "Critical Evaluation of Nutrition Research". While sitting through two hours of discussions on research methods may seem tedious to some, I came to the conclusion that this class is one that everyone should be required to take. Maybe not just on nutrition, but on understanding health studies in general. I started this blog because I began to feel frustrated with all of the contradictory studies on health and nutrition that were reported on a daily basis. I felt like it was important to filter through all the reports to try and help people understand the basics, but it isn't always that simple. There are those who believe if you see it on the news, it's the truth. There are also those who write off anything they hear on the news choosing to ignore the "hype". Most people want someone to filter through all the contradictory information, and just give them the truth.
This class gave me a better understanding of what goes into making a successful study, why nutrition based research can prove to be so difficult, and again reiterated why we really should open a critical eye when evaluating research. Often times a headline completely sensationalizes a study, with the results being a lot different than the media makes it appear.
I decided to put my newly honed critical evaluation skills to the test today because I keep seeing headlines publicizing a new study published in the Archives of Internal Medicine linking high levels of red meat consumption with increased risk of mortality. Before actually reading any of the news reports (aside from the scary headlines) I decided to go straight to the source. You can too by clicking here.
Here is what I found: I was actually impressed with this study. The researchers followed a group of a half a million men and women aged 50-71 (a cohort from the National Institute of Health-AARP Diet and Health Study) over a period of ten years to assess if high levels of red meat consumption produced an increased risk of death. Often a study is flawed because they don't adjust for additional variables, and as food and diet work synergistically together to produce health benefits or risks, it is extremely important to statistically adjust for these things. This study adjusted for a wide range of factors, including age, race, BMI, family history of cancer, fruit and vegetable consumption, smoking, and overall energy intake (total calories eaten), plus a few others.
The result? One of the important things the class I took really drilled into my head was the necessity of reading and understanding the statistics of the study. A result means nothing if it isn't statistically significant meaning that a result has very little chance of being an effect of an unknown factor and not the issue being studied. This study did in fact show some important statistically significant findings.
The researchers divided the groups into quintiles of intake after analyzing their data and then compared all of the intake levels with the lowest level of consumption. For this study the highest intake level was 62.5 grams of red meat per 1000kcals (so this is about 2.23 ounces of red meat per 1000 kcals) and the lowest intake level was 9.8 grams per 1000 kcals (less than 0.5 grams). Both men and women who consumed the higher levels of red meat as compared the men and women in the lower were at increased risks for mortality. Smaller, but still significant results also showed an increase in overall deaths for those men and women who ate the highest amount of processed meats versus those who ate the least. And there appeared to be an inverse relationship between mortality and those who ate white meat.
Bottom line for the study: More red meat equals more chance of death. The highest quintile of intake started at 2.33 ounces of red meat per 1000 kcals, and as most restaurants serve no smaller than a 6 ounce piece of meat on their menus, you can see that this is not very much. But again, nutrition studies are tough because we don't live in a bubble where the only thing affecting our health is the nutrient being studied. We do all kinds of things to our bodies that can skew the results.
Ok, you may ask, so what's your point? Do I eat red meat or not? Take a look at the bigger picture. This study also noted the fact that people who ate the high levels of red meat were also less likely to exercise, to eat fruits and vegetables, and , all components also linked to health issues, and not all the news outlets reported that part of the study. My advice? I for one choose not to eat red meat, but not because I think that ground beef once a week is going to kill me. If you are someone who enjoys red meat you can keep it in your diet as long as it is eaten in moderation (that means not every day or in huge amounts), and it is supplemented by an overall healthy diet and activity level. The American Institute for Cancer Research, The World Cancer Research Fund and The American Cancer Society all echo this advising the importance of limiting your red meat intake.
Please feel free to ask if you have any more questions about this study. Enjoy your weekend!