More on good saturated fats

A few months ago the big news in nutrition (at least, as far as the national media is concerned) was that not all saturated fat is bad for you. We wrote about two studies that looked at different types of saturated fat: one discussing very-long-chain saturated fatty acids (a certain type of saturated fat), and another looked at the risk of diabetes associated with greater intake of high-fat dairy products and higher-fat unprocessed meats.

The latter research, while long term, relied on the participants to accurately report their diets - then assumed that their diets would remain the same throughout the study. While it's reasonable to believe that people tend to eat about the same things over time - we are creatures of habit, to be sure - as a research method it is not nearly as powerful as, say, yearly dietary questionnaires. Nor is it nearly as powerful as simply providing all of the participants' food for a period of time.

That's quite expensive, however, and of necessity that type of research is usually limited to small groups of subjects, as in today's study, published in the American Journal of Clinical Nutrition (2015;102:573-81). A team in Denmark recruited 14 overweight, postmenopausal women to participate in their feeding study. Each participant was provided with all meals and snacks for two weeks, in amounts designed to maintain their body weight. They were randomly assigned to one of three types of diets. Two of the diets were higher in saturated fat, while a third diet was lower in fat, as follows:

A CHEESE diet, in which they consumed 36% of their energy from fats (half of that in saturated fat), 49% of their energy from carbohydrates, and 15% from protein. Half of the fats came from high-fat cheese.

A MEAT diet, with 36% of energy from fat (also half of that in saturated fat), 49% of energy from carbohydrates, and 15% from protein. Half of the fats came from high-fat processed and unprocessed meats.

A CARB (low-fat) diet, with 23% of energy from fat (also half in saturated fat), 60% of energy from carbohydrates, and 15% from protein. This diet did not include any dairy products but did include lean meats.

After two weeks (known to be the amount of time to see dietary changes in cholesterol levels), the participants showed no change in their weight, waist or hip circumference, or blood pressure. Those who followed the CHEESE diet improved their HDL cholesterol (the good cholesterol) by 5% over the (low-fat) CARB diet, while those on the MEAT diet improved their HDL by 8% over the CARB diet. There were otherwise no significant differences between the three diets in total cholesterol or LDL cholesterol (the bad cholesterol).

What this means for you

One thing that concerns us about this study is that the researchers do not specify the types of meat consumed in the MEAT diet. It is simply described as "high-fat processed and unprocessed meats," although the study does mention beef and pork. By comparison, the authors describe the CHEESE diet as including half Danbo cheese (a popular local cheese containing 27% fat by weight) and half cheddar (33% fat by weight). Another limitation is the relatively short duration of the study: while 2 weeks are enough to see the types of changes they were investigating, a longer term study that included many more people would provide more insight into the effects of the saturated fats from the respective specific sources. What we can conclude from this study is that demonizing a particular nutrient - or even a particular food - is not the answer. High-quality food sources, eaten in moderate amounts, is the most reasonable, and the most personally sustainable, solution to a healthy diet.

First posted: September 2, 2015