This is part 1 in a series that will examine the current scientific evidence regarding cardiovascular disease/coronary heart disease/dietary saturated fat/blood lipids/etc. After I sat down and started collecting articles for my research, I realized just how big of a topic this is, and that it deserves to be broken up into several parts in a series.
Most people's first reaction to hearing a recommendation to eat more saturated fat, more animal fat, more dietary cholesterol, and more meat (including red meat) is usually something like "Whoa. What about my arteries? Won't that give me heart disease?" Despite all of the propaganda since the middle of the last century from the government in support of the diet-heart hypothesis and against dietary fat, cholesterol, and red meat, the scientific evidence doesn't back it up.
There are scientists who have spent a whole lot more time than me reading, researching, and thinking about this subject. And they've published review articles in peer-reviewed journals. What's the big deal about review articles? They are a critical part of the scientific literature, and are, quite simply, comprehensive reviews/summaries of experiments published to date testing any given hypothesis (in this case, the diet-heart hypothesis). Published individual experiments can be great sources of information. But review articles that critically examine dozens of published experiments spanning decades can provide much better insight about the current state of knowledge on a given topic. That said, let's take a look at what these review articles found.
First: A systematic review of the evidence supporting a causal link between dietary factors and coronary heart disease, which concludes that there is insufficient evidence of association between coronary heart disease (CHD) and intake of saturated and polyunsaturated fatty acids, total fat, meat, eggs, or milk.
Did you get that? According to the Methods Section, they covered experiments published from 1950 up until June 2007, and concluded that there is insufficient evidence among studies spanning those 57 years to support the idea that saturated fat, meat, milk, or egg consumption is associated with developing coronary heart disease. What they did find to be strongly associated with developing CHD was consumption of trans-fatty acids and foods with high glycemic index or load. I plan to go into much more detail in a follow-up post about what the literature says the real risk factors of developing CHD are.
Up next we have: The questionable role of saturated and polyunsaturated fatty acids in cardiovascular disease. It's a fantastic article that is really worth reading all the way through to see how Dr. Ravnskov dismantles the diet-heart hypothesis study by study, but unless you work some place that subscribes to this journal, you won't be able to see the full text. The abstract is informative, albeit a little dense, but the overall conclusions are just as strong as the first article. Here are some quotes:
"Considering the emphasis with which the “prudent” diet has been promoted by health authorities all over the Western world and the impact that this advice has had, it was a great surprise to discover the almost total lack of scientific evidence for that diet. In fact, support was mainly found in studies of the lowest scientific validity, the early ecological studies whose findings could be explained in another way."
"The low intake of animal fat in a few ethnic groups in the cross-sectional studies cannot explain their lack of atherosclerosis and CVD [cardiovascular disease] because other groups such as the Asian Indians and the vegetarian Seventh-Day Adventists also consume little fat but have a relatively high rate of CVD, while others, such as the people on Crete and in western Finland, the Navajo and Seminole Indians, the Masai warriors, some of the Japanese emigrants, not to mention the Punjabi, the most striking example, consume a lot of animal fat but have relatively little CVD."
This review spans 1943-1997, and reaches the same conclusion as the first article, that dietary saturated fat has nothing to do with developing cardiovascular disease.
One more, for now, from 2010: Meta-analysis of prospective cohort studies evaluating the association of saturated fat with cardiovascular disease, that concluded "A meta-analysis of prospective epidemiologic studies showed that there is no significant evidence for concluding that dietary saturated fat is associated with an increased risk of CHD or CVD."
This review includes studies from 1960-2010, and reaches the same conclusion as the others.
That's all for Part 1, but if you are curious to learn more, I've already collected a large number of citations in the Science! section of the site that I will be including in follow-up posts. In fact, you can go to the Science! page and click on any of the tags if you are interested to learn more about a specific topic.
In the meantime, don't feel guilty about enjoying your veggies roasted in coconut oil or sauteed in beef tallow.
