Tag Archives: cardiovascular risk factors

New Analysis Finds Low-Carb Diets Reduce Heart Disease Risk Factors

Obesity Reviews just published details of a recent meta-analyis of low-carbohydrate diet effects on cardiovascular risk factors.

A systematic review and meta-analysis were carried out to study the effects of low-carbohydrate diet (LCD) on weight loss and cardiovascular risk factors (search performed on PubMed, Cochrane Central Register of Controlled Trials and Scopus databases). A total of 23 reports, corresponding to 17 clinical investigations, were identified as meeting the pre-specified criteria.

Over a thousand obese patients were involved.  By eating low-carb, average body weight decreased by 7 kg (15 lb), body mass index dropped by 2, blood pressure dropped by 3-4 mmHg, triglycerides decreased by 30 mg/dl, hemoglobin A1c dropped by 0.21% (absolute decrease), insulin levels fell by 2.23 micro IU/ml, while HDL cholesterol rose by 1.73 mg/dl.  LDL cholesterol didn’t change.

The authors conclusion:

Low-carboydrate diet was shown to have favourable effects on body weight and major cardiovascular risk factors; however the effects on long-term health are unknown.

I haven’t see the full text of the article yet, so I don’t know the carbohydrate level under review.  I bet it’s under 50 g of digestible carb daily.  My Low-Carb Mediterranean Diet starts at 20-30 grams a day.

Steve Parker, M.D.

Reference:  Santos, F.L., et al. Systematic review and meta-analysis of clinical trials of the effects of low carbohydrate diets on cardiovascular risk factors. Obesity Reviews. Article first published online: 20 AUG 2012. DOI: 10.1111/j.1467-789X.2012.01021.x

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Filed under Carbohydrate, Heart Disease, Weight Loss

Paleo Diet and Diabetes: Improved Cardiovascular Risk Factors

Compared to a standard diabetic diet, a Paleolithic diet improves cardiovascular risk factors in type 2 diabetics, according to investigators at Lund University in Sweden.

Researchers compared the effects of a Paleo and a modern diabetic diet in 13 type 2 diabetic adults (10 men) with average hemoglobin A1c’s of 6.6% (under good control, then).  Most were on diabetic pills; none were on insulin.  So this was a small, exploratory, pilot study.  Each of the diabetics followed both diets for three months.

How Did the Diets Differ?

ResearchBlogging.orgCompared to the diabetic diet, the Paleo diet was mainly lower in cereals and dairy products, higher in fruits and vegetables, meat, and eggs.  The Paleo diet was lower in carbohydrates, glycemic load, and glycemic index.  Paleo vegetables were primarily leafy and cruciferous.  Root vegetables were allowed; up to 1 medium potato daily.  The Paleo diet also featured lean meats [why lean?], fish, eggs, and nuts, while forbidding refined fats, sugars, and beans.  Up to one glass of wine daily was allowed.

See the actual report for details of the diabetic diet, which seems to me to be similar to the diabetic diet recommended by most U.S. dietitians.

What Did the Researchers Find?

Compared to the diabetic diet, the Paleo diet yielded lower hemoglobin A1c’s (0.4% lower—absolute difference), lower trigylcerides, lower diastolic blood pressure, lower weight, lower body mass index, lower waist circumference, lower total energy (caloric) intake, and higher HDL cholesterol.  Glucose tolerance was the same for both diets.  Fasting blood sugars tended to decrease more on the Paleo diet, but did not reach statistical significance (p=0.08).

So What?

The greater improvement in multiple cardiovascular risk factors seen here suggests that the Paleo diet has potential to reduce the higher cardiovascular disease rates we see in diabetics.  Larger studies—more participants—are needed for confirmation.  Ultimately, we need data on hard clinical endpoints such as heart attacks, strokes, and death.

These diabetics had their blood sugars under fairly good control at baseline.  I wouldn’t be surprised if diabetics under poor control—hemoglobin A1c of 9%, for example—would see even greater improvements in risk factors as well as glucose levels while eating Paleo.

I see a fair amount of overlap between this version of the Paleo diet and Dr. Bernstein’s Diabetes Solution diet and the Low-Carb Mediterranean Diet

Steve Parker, M.D.

Reference:  Jönsson, T., Granfeldt, Y., Ahrén, B., Branell, U., Pålsson, G., Hansson, A., Söderström, M., & Lindeberg, S. (2009). Beneficial effects of a Paleolithic diet on cardiovascular risk factors in type 2 diabetes: a randomized cross-over pilot study Cardiovascular Diabetology, 8 (1) DOI: 10.1186/1475-2840-8-35

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Filed under coronary heart disease, Glycemic Index and Load, Mediterranean Diet

Saturated Fat is Bad – If You’re a Mouse!

I was excited to see an article, “A Look at the Low-Carbohydrate Diet,” in the December 3, 2009, New England Journal of Medicine.  I was quickly disappointed.

Expecting a scholarly review of low-carb eating in humans, I found an exposition of a diet study in mice.  And not just your garden-variety mice.  These were a lab strain deficient in apolipoprotein E, which makes them particularly susceptible to atherosclerosis when fed a “Western” high-fat, moderate-protein, moderate-carbohydrate diet instead of standard lab chow.

Click on the HeartWire reference below for a discussion of the original mouse research.  I wrote a short post about it in August, 2009.

The article author, Dr. Steven R. Smith, states the usual concern that high-fat (especially saturated fat), high-protein, low-carb diets may cause cardiovascular disease such as atherosclerosis (hardening of the arteries).  He doesn’t mention the scientific evidence showing little or no role of total and saturated fat in cardiovascular disease.

I give credit to him for mentioning that high-fat low-carb diets area associated with improvement in several cardiovascular risk factors such as HDL cholesterol and blood pressure.  He thought they also improve ( lower) LDL cholesterol levels—not something I’ve been impressed with.  He didn’t mention the lowering of triglycerides so often seen. 

Dr. Smith explains that, compared with controls, mice eating the Western high-fat low-carb diet demonstrated progression of atherosclerosis, perhaps mediated by elevated nonesterified fatty acids and low numbers of endothelial progenitor cells.  These are not yet considered classic cardiovascular risk factors in humans.

To quote Dr. Smith, his main point is that . . .

The work of Foo et al suggests that the [high-fat low-carb] diet might increase the risk of cardiovascular disease through mechanisms that have nothing to do with these “usual suspects” [e.g., LDL and HDL cholesterol, blood pressure, C-reactive protein] and so provides a note of caution against reliance on the traditional cardiovascular risk factors as a gauge of safety.

He rightfully calls for investigation of these issues in humans, but . . .

In the meantime, the ageless advice applies to the consumer of the [high-fat low-carb] diet and other fad diets: caveat emptor.

Take Home Points

I agree that human studies are needed.

As the evidence in favor of the safety and efficacy of high-fat low-carb diets increases, the reigning medical establishment is looking for new ways to discredit them.  This attempt is pathetic.

Unfortunately, the typical physician reading NEJM will skim this article and conclude, “Yeah, I was right—the Atkins diet causes heart disease.  Low-fat high-carb is still the best.” 

If you have beloved pet mice that are deficient in apolipoprotein E, don’t feed them a high-fat low-carb diet.

Steve Parker, M.D.

References:

Smith, Steven R.  A Look at the Low-Carbohydrate Diet.  New England Journal of Medicine, 361 (2009): 2,286-2,288.  [This may cost you $10 USD.]

Foo, S.Y., et al.  Vascular effects of a low-carbohydrate high-protein dietProceedings of the National Academy of Sciences of the United States of America, 106 (2009): 15418-15423.   doi: 10.1073/pnas.0970995106  [This may cost you $10 USD.]

Busko, Marlene.  Atherosclerosis heightened in mice fed low-carb, high-protein diet.  HeartWire, August 26, 2009.  [Free]

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Filed under Carbohydrate, Fat in Diet