You probably have heard about the new popular diet, “Paleo diet”, revered by fans of crossfit and heavy weight lifting. In short, this diet is trying to simulate a cave man diet. Those people eliminate sugars and grains and substitute it with the more meat, eggs and fat in their meals. They also probably told you that they also lose weight, and feel great. It’s hard to believe, just by knowing how much fat and cholesterol they consume from animal fats, that it doesn’t hurt them. It is well known that animal fat is bad for our arteries and for the heart. Or is it bad?
Recent research just published by The American Journal of Clinical Nutrition questions that well-known “fact”. Thomas Sanders and his colleges investigated Animal fat and Plant fat diets of 121 people over a 24 week period and came with a shocking conclusion; “animal fat does not impair functions of the arteries, and does not lead them to stiffness.” This could mean it is not bad for the heart.
Could doctors then be wrong advising less animal fat in our diets? It’s hard to say, but always be cautious about new studies that speak against other well accepted research. Also note this study was done on insulin resistant patients, and while some people say it should work even better for healthy people, the answer is- we really don’t know that yet. Just remember, a balanced diet works best.
Just to clarify, Animal fat examples are lard, tallow, butter and other fats that are made of or from animals and in “nutrition” are called Saturated fats (SFA). Plant fats- olive oil, corn oil and other liquid plant oils are called Unsaturated fats (which could be polyunsaturated (PUFA) or monounsaturated (MUFA) fats).
One hundred twenty one participants were insulin resistant but are not diabetic, 51 years old, mostly white/Caucasian women that were overweight or obese in this study. Volunteers were assigned to one of the 5 diets: 1) High-Saturated & High Glycemic Index diet; 2) High Monounsaturated & High Glycemic Index diet; 3) High Monounsaturated &Low Glycemic Index diet; 4) High –Carbohydrate & High Glycemic diet; and 5)High Carbohydrate & Low Glycemic Diet. The researchers used measurement of endothelial function called Flow Mediated Dilation (FMD). The stiffness of the arteries was measured using Wave Velocity (WV). The oxidative stress was measured using plasma 8-Isoprostane F2a-III, which becomes high when oxidant stress is increased.
Compared with High SFA diet, SFA were reduced to less than 10% in all other diets. Intake of MUFA was the highest in the MUFA diet and intake of carbohydrates similarly was the highest in the High Carbohydrate diet. The researchers concluded that that over the period (4 months), 121 overweight participants eating one of five assigned diets were found to have no significant difference in their artery function, pulse stiffness, carotid to femoral pulse wave velocity or plasma oxidative stress. However, the research team observed pulse stiffness to be lower with the High Carbohydrate than High SFA diets.
Thank you so much for this post! I’ve been wondering if the Paleo claims are always up-to-date with scientific information.