Americans have been conciously avoiding saturated fat since the '80s, but began replacing animal fat with vegetable fat in the 1920s. Has anyone ever stopped to ask why? We are told that saturated fat is bad for us and that it causes heart disease, but is there any evidence to support this?
The answer is no. In fact, the evidence shows that saturated fat is actually very healthy and the lack of saturated fat in the diet explains the increase in chronic disease, obesity, ADHD and more.
If the evidence supports the health benefits of saturated fat, why are we told not to eat it?
I'll be answering that questions in several blogs as it demands a lot of attention.
First, a little chemistry lesson. This will be the boring part, but it is essential to have a basic understanding of the chemistry.
There are three types of fat. Saturated, unsaturated and trans. Saturated fat is generally solid at room temperature such as the fat on meat, butter, coconut oil and palm oil. Saturated fats have no double bonds and are therefore the most stable of the fats and do not go rancid as easily as unsaturated fats.
There are two groups of unsaturated fats. Monounsaturated and polyunsaturated. Examples of monounsaturated fat are olive and peanut oils, chicken skin and lard. Monounsaturated fats have 1 double bond so they are less stable than saturated fats, but more stable than polyunsaturated fats.
Polyunsaturated fats contain 2 or more double bonds and are, therefore, highly unstable. They go rancid very fast. Within the polyunsaturated group are the essential fatty acids, omega-6 and omega-3. Polyunsaturated fats are found in soybean, corn, cottonseed, canola, sunflower, safflower and flaxseed oils and in fish.
What most people don't realize is that all fats have a combination of saturated, monounsaturated and polyunsaturated fats. In whole foods, there is a preponderance of saturated and monounsaturated fats with a small amount of polyunsaturated fats.
There are two types of trans fats, natural and man made. Natural trans fats are found in dairy and meat and are very healthy. They do not have the same chemical structure as man made fats. Man made trans fats are liquid vegetable oils (highly unstable polyunsaturated fats) that have hydrogen added to them to make them more solid at room temperature (fat is composed of carbon and hydrogen). When man makes them, the chemical structure gets all messed up and it becomes a fat that the body will incorporate into tissues, but it doesn't function the same as saturated fat. This is what causes health problems.
End of chemistry lesson. Now for a little history. In America, we are operating under the lipid hypothesis. This hypothesis states that saturated fat and cholesterol in the diet lead to plaque build-up in the arteries causing atherosclerosis which leads to coronary heart disease.
This hypothesis is based on two studies. In the 1950's, David Kretchevsky studied rabbits. He fed rabbits pure cholesterol and noticed that they developed a form of plaque in their arteries. Inspired by this research, Ancel Keys did his famous 6 country study. He basically hand picked 6 countries out of 22 and determined that the more fat available for consumption in a country, the more deaths from heart disease occured.
Sounds convincing, but there are some flaws. First, rabbits are herbivores and have no way to process cholesterol (cholesterol is found only in animal foods). We cannot compare a rabbit to humans because we don't have the same physiology. In Key's 6 country study, if you added the other 16 countries, there is no correlation between available fat (Keys did not test actuall fat intake) and heart disease death. Keys choose the countries that would give the result he was looking for.
That is not good science. Good science involves developing a hypothesis and then trying to prove the hypothesis wrong. But when the lipid hypothesis was formed, instead of trying to prove it wrong, we have desparately tried to prove it true. The reason we are still trying to prove it is because most of the studies have actually proved it false. We just don't hear about those studies.
Stay tuned next time for some of those unheard of, but published studies and the reason why they are kept from us.