Replacing Saturated Fat with Heart Healthy Oils

If you are a Gary Taubes fan you may like this one. A link to this fascinating little study was posted by blogger David Evans on his "Healthy Diets and Science" (a very fun blog to dig around in). The name of the study is: "Use of dietary linoleic acid for secondary prevention of coronary heart disease and death: evaluation of recovered data from the Sydney Diet Heart Study and updated meta-analysis" and it was published this month in BMJ. The Sydney Diet Heart Study was conducted in 1966-1973 with 458 males, aged 30-59 years, who already received care for coronary issues .  The study was to measure the effectiveness of replacing dietary saturated fat with omega 6 linoleic acid (safflower oil).  The researchers assumed that the safflower oil would decrease total serum cholesterol and thereby increase health benefits. And yes, the cholesterol levels did decrease.  However, death rates for all causes of mortality rose for those on the "heart healthy" oils.  We all know the extent of dietary advice given that we should replace saturated fat with omega-6 rich vegetable oils such as safflower, soybean, and corn oil, and yet most of us are unfamiliar with the lack of evidence to conclusively back this up. Here are some eerie comments from the study:

"Advice to substitute vegetable oils rich in polyunsaturated fatty acids (PUFAs) for animal fats rich in saturated fatty acids (SFAs) has been a cornerstone of worldwide dietary guidelines for the past half century. When this advice originated in the 1960s, PUFAs were regarded as a uniform molecular category with one relevant biological mechanism—the reduction in blood cholesterol. Omega 6 (n-6) linoleic acid (LA) was the best known dietary PUFA at the time. Therefore, the terms “PUFA” and “LA” were often used interchangeably when interpreting clinical trial results and delivering dietary advice...
However, there is currently no clinical trial evidence indicating that replacing SFAs with n-6 LA, without a concurrent increase in n-3 PUFAs, lowers the risk of cardiovascular disease or death. Thus, benefits attributed to PUFAs as a general category might be due to n-3 PUFAs specifically, particularly eicosapentaenoic acid and docosahexaenoic acid. Such benefits are not necessarily generalizable to n-6 LA or other PUFA species. Since n-6 LA is the most abundant dietary PUFA, and edible oil sources with markedly different contents of fatty acids are commercially available it is important to ascertain the benefits and risks specific to n-6 LA."

"Oxidation products of n-6 LA have been implicated in the pathogenesis of cardiovascular disease,  and alcohol use and cigarette smoking are major sources of free radical mediated oxidation.Therefore, we hypothesized that alcohol use or smoking at baseline modified the association between longitudinal change in PUFA intake and mortality using likelihood ratio tests (α=0.15). The original SDHS investigators posited that the LA intervention would reduce serum cholesterol as an intermediate for the prevention of cardiovascular death. Thus, to examine whether the magnitude of postrandomization changes in total blood cholesterol were associated with mortality, we calculated hazard ratios for each mortality outcome as a function of time varying change from baseline in total blood cholesterol."

"Among intervention patients (in whom the PUFA increase was n-6 LA from safflower oil), an increase of 5% of food energy from n-6 LA predicted 35% and 29% higher risk of cardiovascular death and all cause mortality, respectively (models adjusted for age, dietary cholesterol, body mass index at baseline, smoking, alcohol use, and marital status)."

"Conclusions Advice to substitute polyunsaturated fats for saturated fats is a key component of worldwide dietary guidelines for coronary heart disease risk reduction. However, clinical benefits of the most abundant polyunsaturated fatty acid, omega 6 linoleic acid, have not been established. In this cohort, substituting dietary linoleic acid in place of saturated fats increased the rates of death from all causes, coronary heart disease, and cardiovascular disease. An updated meta-analysis of linoleic acid intervention trials showed no evidence of cardiovascular benefit. These findings could have important implications for worldwide dietary advice to substitute omega 6 linoleic acid, or polyunsaturated fats in general, for saturated fats."

Food and Bugs - Two Different TED Talks

There are two different TED talks here that I found very interesting. Both talks are fascinating and easy to understand. TED talks have a short format, under 18 minutes I believe.

The first one is from Stephan Guyenet on "The American Diet: a Historical Perspective". He discusses the different composition of diet today versus about a hundred years ago. There has been enough of a change to raise a few eyebrows. Stephan also has a blog Whole Health Source.


The second TED talk is from Bonnie Bassler on "How Bacteria Talk" (just scroll down to the little TED screen). Ms. Bessler is a microbial geneticist at Princeton University.  In the late 1990's she was studying the glowing bacteria in angler fish (if you've seen Finding Nemo, this is the monster fish with the "pretty light"). She tried to figure out how they all knew to glow at the same time. Up till then, for the most part, bacteria were not considered intelligent enough to communicate with each other. She discovered that not only do they communicate, they are multi-lingual. The have an intra-species language and a sort of universal language that most bacteria seem to understand.

Can a Grain-Free Diet Reverse Tooth Decay?

Here's an interesting post from Stephen Guyenet of Whole Health Source called Dr. Mellanby's Tooth Decay Reversal Diet. He discusses a study published in 1924 called "Remarks on the Influence of a Cereal-free Diet Rich in Vitamin D and Calcium on Dental Caries in Children". Three different diets were studied for their effect on dental caries. The grain-free diet supplemented with vitamin D not only slowed the rate of dental caries, but actually reversed some decay.

What's the Fat on Breakfast?

For some reason I have to start my day with a high fat breakfast. If I don't then I can't make it to lunch and I just don't feel right. I could eat a plate of veggies for dinner and be fine, but for some reason I need that fat in the mornings like some folks need coffee. So I found this article very interesting:

Bacon or Bagels? Higher Fat at Breakfast May Be Healthier Than You Think

Butter'em Up!

I love tips that help make food more nutritious and taste great. Who doesn't? Here's an interesting post from Chris Kresser of The Healthy Skeptic. I usually add a little pat of butter to my cooked veggies for flavor, but I had no idea it was greatly improving the utilization of the nutrients.