High Carbohydrate Intake Worse than High Fat for Blood Lipids:
Recent data presented at the World Heart Federation’s World Congress of Cardiology & Cardiovascular Health 2016 (WCC 2016) in Mexico City last month may radically change our perspective on how carbohydrates and different types of fats affect blood cholesterol and other lipid biomarkers. The presentation was based on data from the Prospective Urban Rural Epidemiological (PURE) study. The data have not been published yet, and the results are only available in an abstract
In the above study, the only benefit of a high carbohydrate diet was a lowering of TC and LDL-C. However, the effect on other lipid biomarkers such as HDL-C, TG, and ApoB/ApoA ratio may be harmful.
A diet rich in SFAs raised TC and LDL-C but lowered TG while a diet rich in MUFAs improved all lipid biomarkers. A diet high in PUFAs had a mixed effect on lipid biomarkers.
The study suggests that placing carbohydrates at the bottom of the food pyramid based on their effect on blood cholesterol was a mistake. In fact, the data show that replacing dietary carbohydrates with different types of fat may improve lipid profile.
In an interview on Medscape, Dr. Mahshid Dehghan, the principal author of the abstract said (3):
To summarize our findings, the most adverse effect on blood lipids is from carbohydrates; the most benefit is from consumption of monounsaturated fatty acids; and the effect of saturated and polyunsaturated fatty acids are mixed. I believe this is a big message that we can give because we are confusing people with a low-fat diet and all the complications of total fat consumption, and WHO and AHA all suggest 55% to 60% of energy from carbohydrates.
Today, most experts agree that diets high in SFAs or refined carbohydrates are not be recommended for the prevention of heart disease. However, it appears that carbohydrates are likely to cause a greater metabolic damage than SFAs in the rapidly growing population of people with metabolic abnormalities associated with obesity and insulin resistance.
I assume we all agree that partially hydrogenated fats (trans-fats) should be avoided. However, the singular focus on reducing the intake of SFAs, and dietary fats in general, may have been counterproductive and promoted the rapidly growing popularity of refined carbohydrates. The recent nutritional data from the PURE study clearly suggest that it is time to shift our focus away from reducing fat in our diet toward reduced consumption of carbohydrates.