Does the Atkins Diet Increase Heart Disease Risk?
A research report earlier this year showed that certain heart disease risk factors are improved more with the South Beach and Ornish diets than with the Atkins diet.
The Atkins diet is higher in saturated fat than standard American fare. It’s the classic low-carbohydrate diet. Current dietary dogma is that high intake of saturated fat promotes atherosclerosis - hardening of the arteries - which in turn leads to premature heart attacks, strokes, and death. Higher saturated fat intake leads to increases in LDL cholesterol, and in HDL choleserol to a lesser degress.This is a major concern about the Atkins diet and other low-carb plans among traditional medical practitioners and dietitians. [I and others have questioned this theory, which is called the Diet-Heart Hypothesis.]
Researchers studied 18 experimental subjects at a healthy weight, trying them sequentially on three diets: 1) Atkins maintenance phase diet (50% fat), 2) South Beach maintenance phase (30% fat), and 3) Ornish diet (vegetarian, 10% fat). The goal was not weight loss; it was adherence to the diet. Heart disease risk factors were measured periodically.
Here are the main findings:
Participants ate about 3 grams of saturated fat daily on Ornish, about 14 grams on South Beach, and 30 grams on the Atkins diet.
An 8% increase in LDL cholesterol (the bad cholesterol) seen with Atkins was not statistically significant - which means there is a fair chance the 8% increase was due to chance alone rather than a true effect of the diet.
LDL cholesterol decreased by 12% on South Beach, and by 17% on Ornish. These were statistically significant.
As saturated fat intake increased, flow-mediated vasodilation decreased significantly. Compared with Atkins, the other groups showed significant decreases in apolipoprotein B.
Overall, the observed blood changes changes would tend to favor the South Beach and Ornish diets over Atkins, in terms of future heart health.
But this was a very small, short-term study, so it’s difficult to apply the results to common clinical situations. There is ligitimate cause for concern, however.
If the Diet-Heart Hypothesis is wrong, then the observed lipid changes don’t matter.
So, would a long-term Atkins diet actually increase heart disease? We don't know for sure. Hundreds of thousands of people have been eating Atkins-style for years. What we need now is a well-designed study comparing their long-term health and longevity outcomes with a group of people following a standard American diet.
For evidence-based tips on a heart-healthy diet, see Monica Reinagel's summary.
-Steve Parker, M.D.
References:
Miller, Michael, et al. Comparative Effects of Three Popular Diets on Lipids, Endothelial Function, and C-Reactive Protein During Weight Maintenance. Journal of the American Dietetic Association, 109 (2009): 713-717.
Moens, A.L., et al. Flow-mediated vasodilation: a diagnostic instrument, or an experimental tool? Chest, 127 (2005): 2,254-2,263.
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Posted by: Monica Reinagel | Jul 16, 2009 6:17:59 PM
I have a pet theory--but no way of validating it. I suspect that diets high in saturated fat MIGHT increase heart disease risk BUT only when the diet is ALSO high in refined carbohydrates. Like I said, it's only a hypothesis but it would explain a lot, wouldn't you agree?
Posted by: joy | Jul 17, 2009 3:54:32 PM
Comparing one bad diet (Atkins) to another bad diet (standard American) is a pretty useless study. What would be the point of that?
Posted by: Steve Parker, M.D. | Jul 22, 2009 2:40:13 PM
Hi, Joy.
Atkins enjoyed an astounding surge of popularity at the turn of the century, in the U.S. Where I live, people were opening Atkins stores and "low-carb" stores in strip malls. Most are out of business now. But the Atkins diet will rise again, and more than a few people still follow its guidelines.
One of the most appealing aspects of Atkins is that you don't have to count calories or otherwise monitor intake as much as with other diets, as long as you follow the other guidelines (mostly, avoid carbohydrates). Simply put, it's simple. And most do lose weight.
But even now, we're not sure about the long-term results of Atkins-style eating. It might promote cancer because of the red meat, but it's not definitely proven. It might promote heart disease because of the saturated fat, but it's not definitely proven. Etc.
It's all well and good to look at blood levels of lipids and inflammatory markers. They provide clues. But where the rubber meets the road is disease and mortality rates. And its still possible that Aktins beats the standard American diet in that arena. Hence, the reason for the study above.
I'm starting to sound like a huge Atkins fan. I'm not. Among the common ways-of-eating, I favor the Mediterranean diet as the healthiest. I'll change my mind when scientific data dictate otherwise.
-Steve
Posted by: Steve Parker, M.D. | Jul 22, 2009 2:59:39 PM
Hey, Monica.
Your theory would explain a lot. I've seen it discussed in the scientific literature. No firm conclusions yet.
-Steve
Posted by: Jim Purdy | Jul 28, 2009 8:53:47 AM
My diet combines some features of both Ornish and Atkins.
Like Atkins, I try to avoid carbs. Like Ornish, I try to avoid animal fats.
I try to eat a low-carb mostly vegan diet, with lots of mono-unsaturated fats from avocados, pecans, walnuts, peanut butter, ground flaxseed, and extra virgin olive oil.
I am overweight, and I have Type 2 diabetes. My diet seems to be helping to lower my weight and my diabetic blood glucose.
Since my diet is high-fat, and therefore high-calorie. I eat very small portions. I try to eat 5 or 6 very (VERY!) small meals per day.
The mono-unsaturated fats seem to be very filling, and the very small meal sizes may be shrinking my stomach. Also, my blood glucose stays very steady throughout the day.
My food cravings are way down, which makes it a lot easier to lose weight.
Posted by: Steve Parker, M.D. | Jul 30, 2009 6:33:53 PM
Hi, Jim. It would be interesting to know what percentage of your total calories is derived from carbohydrates. Standard American is about 55% of calories from carbs. I usually consider a vegan diet to be high-carb. But it sounds like you've designed a lower-carb version, using plant-derived fats and proteins. Lots of tofu?
-Steve
