Ah, Bacon, or butter, or beef! Whenever I tell people that I eat these foods and they are healthy (like the Chicken Bacon Quinoa Soup I posted yesterday) I see this look of disbelief or even fear come across their faces. Yes, saturated fat and cholesterol are not bad for you, as you have been told for decades. In fact, saturated fat has always been an integral part of our diet and our physiology. If you look logically and critically at the evidence that saturated fat is bad for your health, you will see it is very weak. Additionally, more and more research supports the importance of these lipids in your diet for overall health and how replacing them with carbohydrates (especially processed) and vegetable oils is actually detrimental to your health.
Some puzzling paradoxes pop up, especially for me, regarding saturated fat. Consider the following:
Half of the fatty acids that make up our cell membranes are saturated fats.
Saturated fat makes up only 26% of atherosclerotic lesions in coronary artery disease.
Carbohydrates are converted into the saturated fat palmitic acid in the body when ingested in quantities exceeding the glycogen storage and immediate energy needs.
Eating saturated fats decreases circulating levels of saturated fats in the blood due to increased use for cellular energy and decreased production.
Mother's milk contains high levels of saturated fats and lack of saturated fat in an infants diet is related to an infant's risk of failure to thrive.
Your heart's prefered energy source is saturated fat and high concentrations of steric and palmitic acids are located the in adipose stores that is in close proximity to the heart.
Your HDL levels are strongly correlated with your dietary fat intake and your triglyceride level is strongly correlated with your dietary carbohydrate intake.
If we look back through history, saturated fat has been a staple in the human diet. For millions of years humans have received a significant amount of their Calories from animal fat. Experts estimate that 65% of the Paleolithic man's diet was animal based, and only 35% plant based. Animal fat has always been a significant part of human's diets up until 100 years ago. At that point, food processing developed. The earliest reports of heart disease were in rare cases in the 1920s. Animal fat consumption decreased significantly from 1910-1970 due to the increased prevalence of processed foods and fear of the animal fat's and cholesterol's proposed negative relationship with heart disease. Concurrently, processed vegetable oils and processed carbohydrates increased significantly because of cheaper costs and longer shelf-lives.
The Seven Countries Study, a large nutrition and heart disease observational study, is most famous for first linking saturated fat intake to heart disease in the 1950s and 1960s. In this study, Americans were found to have a greater prevalence of heart disease and higher saturated fat intakes compared to other countries, such as Japan. Researchers made a leap of faith inferring causality- assuming higher saturated fat intakes causes heart disease. Whola, the Lipid-Heart Hypothesis is born! Too bad they didn't consider processed carbohydrate and processed vegetable oil intake. They probably would have seen different results. Think about it, people eating hamburgers are probably eating French fries (processed oils and high-starch carbohydrates) and soda (processed sugar). They go hand in hand in western culture.
Subsequent animal studies showed detrimental effects of cholesterol on heart disease, which you continue to hear today. Lesser known, is the the details of those studies. The cholesterol used was in high doses and oxidized (rancid) cholesterol, stored in vegetable oil and fed to herbivores (such as rabbits)! How about that, feed an animal a diet that they have not evolved to eat and they get sick.
More and more studies are finding flaws in the Lipid-Heart Hypothesis or contradictory results. The large, prospective Framingham Heart Study contradicts the Lipid-Heart Hypothesis. The authors conclude "the more saturated fat, cholesterol, and Calories eaten, the lower the serum cholesterol." And, "weight gain and cholesterol levels were inversely related to fat and cholesterol intake."
When processed carbohydrates are removed from the diet, the beneficial effects of animal fat are seen. Several populations around the world that eat lesser processed carbohydrates, but as much or more saturated fats, and appear to have good health. The French, Eskimos, Okinawians in Japan, and the Masai in Africa are all good examples.
In 2007, a large study was published in the Journal of the American Medical Association comparing the Atkins (low carb, high fat) diet to other popular and prescribed low fat/ low saturated fat diets for women. This was a randomly assigned, prospective study. Interestingly, the Atkins' diet showed the largest weight loss, and the biggest improvements in blood lipids and blood pressure.
As the evidence continues to mount against the Lipid-Heart Hypothesis, the media, pharmaceutical companies, and processed food manufacturers continue to propagate its validity. Conventional wisdom and corporate profits are powerful forces to overturn. Additionally, people have a hard time understanding complex phenomenia (such as biochemistry) and find it easier to think in simple cause-and-effect steps: eating fat will make you fat, fatty artery plaques must be caused by eating fat, and carbohydrates are heart-healthy.
Eating whole, unprocessed plant and animal foods (from free-ranging animals eating their native diets) is and always has been healthy. The evidence is in and animal fat is not guilty of causing ill health. Perhaps we should reconsider the 'bystander' to this century-long health crisis: processed vegetable oils and processed carbohydrates.