According to Dr Michael Gregor of Nutrition Facts “People going on low carb diets may not see a rise in their cholesterol levels. How is that possible? Because weight loss by any means can drop our cholesterol. We could go on an all-Twinkie diet and lower our cholesterol as long as we didn’t eat too many. A good cocaine habit could do it. Anything that drops our weight can drop our cholesterol, but the goal isn’t to fit into a skinnier casket; the reason we care about cardiovascular risk factors like cholesterol is because we care about cardiovascular risk, the health of our arteries.”
The crux of the cardiovascular argument from Nutrition Facts now that they can’t rest on low-carb diets negatively affecting blood lipids seems to rest on the purported effect of a higher protein, or higher fat, lower carbohydrate diet on blood flow to the heart. However even Dr Gregor concedes that “There has only been one study ever done measuring actual blood flow to the heart muscles of people eating low-carb diets.”
In this one published study Dr. Richard Fleming (1) enrolled 26 people into a comprehensive study of the effects of diet on cardiac function and measured blood flow within the coronary arteries. The 26 were initially instructed to follow a low fat, low protein, high carbohydrate diet in conjunction with various medical treatments depending on the case. AT the conclusion of the year long study it was found that 10 of the participants had switched to a ‘high protein’ diet, and so comparisons were made between those following the high carb, versus the high protein diet.
The problem with this is that it is always problematic when you change the outcomes you are looking at in an ‘after the fact’ manner. The ‘high protein’ diet is undefined and it is unlikely that the patients were following a homogeneous diet, nor one that was designed for them. Thus it may have simply been a poor diet that they followed. Those who ‘switch’ from an intervention are also more likely to be less compliant overall and it is therefore doubtful that they would have followed the other dietary protocol effectively even if it were a) defined and b) appropriate.
Overall this study says almost nothing about cardiac risk associated with a lower carbohydrate diet, and to ignore the confirmed effects of disglycaemia on cardiac health and the voluminous data showing positive effects on cardiac risk factors from lower-carbohydrate, whole-food based diets is disingenuous at best.