Since the 1970’s, nutrition policy and recommendations have focused on reducing dietary saturated fat (SFA) and cholesterol. However, during the past decade, we’ve begun to learn that SFA and cholesterol are likely under false arrest. They’ve been framed with guilt by association and not with solid facts. Let’s explore the evidence against SFA.
The case against saturated fats dates back to the 1950’s and Dr. Ancel Keys. Dr. Keys was a researcher in public health at the University of Minnesota and a native of the island of Crete off of Greece in the Mediterranean. He observed that people in Minnesota ate more meat, dairy and SFA than people in Crete and they had greater incidence of heart disease. Keys decided that was an important link to the cause of heart disease and he set out to prove it. Keys surveyed 21 countries around the world for their intake of SFA and incidence of heart disease. To his amazement, he found no association – absolutely zero! But, Keys was convinced he was right – and did not want to ruin a good theory with facts – so, he set about to eliminate countries from his survey that did not support his theory. After eliminating the data from 14 countries (including Greece that had the same diet as Crete), he finally found 7 countries that supported his theory and he published what has become known as the “Seven Countries Survey.” Beyond the manipulation of the data in the report, other facts that Keys ignored were that people living in the more topical climate on Crete ate more fresh green vegetables, olive oil, fish, and walked everywhere. No one was over weight and the lifestyle was slow and relaxed, but those facts did not support the SFA story and were hidden from the jury.
Since the 1950’s, the SFA recommendation has remained controversial. There is an axiom in science that a theory that is true will gain momentum over time as other scientists test the theory. For SFA, just the opposite has occurred with doubts increasing over time.
How can we make sense out of the SFA case? The true part of the story is that when the blood contains high amount of SFAs, there are usually increases in the bad cholesterol (LDL). So more SFA seems to equal more bad cholesterol and presumably greater risk for heart disease. But the confusing part comes from why blood levels of SFA increase. We’ve been told it’s because we eat too many animal fats, but since 1970 consumption of red meat declined by 25%, milk by 35% and eggs by 40% and heart disease stayed the same. So the evidence doesn’t fit the crime. The truth is most of the SFA in the blood comes from dietary carbohydrates that the body makes into SFA. Scientists call this de novo lipogenesis or the process of making SFA from carbohydrates in the liver.
Okay, let’s look a little deeper. The SFA that seems to be the problem is called palmitate, a long-chain saturated fatty acid. The interesting thing about palmitate is that after thousands of years of human evolution, it is the only SFA the human can make. When you eat a meal that contains more than about 40 grams of carbohydrates, the body is forced to convert the carbs into fat for storage. The average American diet contains over 100 grams of Carbs at every meal. So about 60 grams must be converted into fat and the only fat that the body can make in the liver is palmitate.
Dr. Julie Hirsch at Rockefeller University established this piece of the puzzle back in 1996. Dr. Hirsch did a cool experiment. He fed test subjects two different diets, one diet with 40% fat and 45% Carbs and the other diet with 10% fat and 75% Carbs. Both diets used the same fat, just different amounts. The fat in each diet was a combination of olive oil, lard and corn oil containing about 31% SFA. So the subjects getting the high carb diet had ¼ the amount of palmitate in their diet. After consuming these diets for 25 days, the subjects eating the high carb diet had significantly more palmitate in their blood than the subjects eating the high fat diet. Really! The subjects getting the high fat diet got 31% of their fat as palmitate and most of the rest was olive oil, while the subjects eating the high carb diet had to convert all of the extra Carbs into fat and the ONLY fat they could make was palmitate. So they ended up with almost 45% more palmitate in their blood eating a low fat diet.
The true evidence in the SFA case is only now being uncovered from the mass of misinformation. The landmark paper by Drs. Frank Hu and Ron Krauss in the American Journal of Clinical Nutrition in 2010 found that after reviewing all of the published scientific reports “…there was no association of dietary SFA with heart disease … except when combined with a high carbohydrate diet.”
We now know that dietary SFA is dangerous only when at least three other dietary problems occur at the same time: 1) eating too many calories (obesity), 2) eating too many Carbs, and 3) eating too little protein. If your diet is balanced and healthy, then SFA are not a problem. This is the healthy balance created by the
METABOLIQ Lifestyle and part of the science incorporated into every
METABOLIQ Shake, Bar, and meal.
For your health,
Dr. Donald K. Layman
Qivana, CSO
Dr. Donald K. Layman is Professor Emeritus of Nutrition in the Department of Food Science and Human Nutrition at the University of Illinois. With more than 33 years of teaching and research experience, Dr. Layman has numerous awards and recognitions, including awards from the American Society for Nutritional Sciences, the Nat
