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High-Carb Diet Raises Insulin Levels Which Spikes Blood Pressure, Research Reveals

Posted Oct 01 2008 8:32pm
In the infamous Stanford JAMA study released in March 2007, researchers found the Atkins low-carb diet was most effective not just for weight loss, but also improvements in certain health markers--including reducing blood pressure.

Now this Reuters story about a new study confirms that a high-carb, low-fat diet indeed leads to an increase in blood pressure. The reason why will astound you!

Lead researcher Dr. Meena Shah, associate professor of clinical nutrition at the Dallas, TX-based University of Texas Southwestern Medical Center, and her team of researchers wanted to see if the highly-touted high-carb, low-fat Dietary Approaches to Stop Hypertension (DASH) diet was the best way to treat high blood pressure.

Dr. Shah used a meta-analysis of ten intervention studies (6 randomized crossover, 1 randomized parallel, and 3 non-randomized) comparing a high-carb, low-fat diet with a low-carb, high-monounsaturated fat diet to see what impact these differences in macronutrients would have on the blood pressure. They took great pains to insure the studies they observed had participants whose weight remained stable.

What did the researchers find?

Using a random-effects model, the high-carb, low-fat diets caused "significantly higher" systolic blood pressure and diastolic blood pressure than the low-carb, high-monounsaturated fat diets did. Even when the meta-analysis included just the randomized crossover studies, the results were similar although not as pronounced.

Despite these clear differences in blood pressure between a high-carb, low-fat diet and a low-carb, high-fat diet, Dr. Shah and her researchers just could bring themselves to push for changes in the DASH diet to include less carbohydrate.

"Diets rich in carbohydrate may be associated with slightly higher blood pressure than diets rich in monounsaturated fat," the researchers concluded. "However, the magnitude of the difference may not justify making recommendations to alter the carbohydrate and monounsaturated fat content of the diet to manage blood pressure."

Well, why the heck not?! Isn't the evidence staring you right in the face? You can bet if the low-carb diet was the one raising blood pressure that this would have been on the front page of every health publication around the world declaring how unhealthy this "extreme" and "dangerous" diet is. But this is the fully-embraced low-fat diet we're talking about here and they've got to protect it from being harmed.

The results of this study appeared in the May 2007 issue of the American Journal of Clinical Nutrition.

This isn't the first time Dr. Shah has published research on the impact of a high-carb diet on blood pressure. In 2005, she had a 6-week study published in the journal Diabetes Care which observed 42 Type 2 diabetics placed on either a high-carb, low-fat diet or a high-fat moderate-carb diet to see how it would impact their blood pressure.

Guess what? Blood pressure went WAY up on the high-carb, low-fat diet. Dr. Shah concluded at the time that "long-term consumption of a high-carbohydrate diet may modestly raise blood pressure in type 2 diabetic patients."

Hmmm, so the longer the exposure to a high-carb diet, the more likely that person eating such a diet will be exposed to what is commonly described as "the silent killer" known as hypertension, or high blood pressure.

Here are two damning studies against consuming the recommended high-carb, low-fat diet for blood pressure conducted by the same researcher and yet she still doesn't believe changes in the recommendations need to be made. What's wrong with this picture?

Aren't these people scientists, who based their decisions on what the data shows them over and over again? It would make perfect sense to conclude based on the evidence that eating carbohydrate in the diet in the excessive amounts that are promoted as healthy is a crazy way to try to lower your blood pressure. It's NOT gonna happen!

Dr. Shah even acknowledges the reason why blood pressure goes up in people who eat a high-carb diet is because of raised insulin levels, aka hyperinsulinemia (something low-carb researcher Dr. Jeff Volek from the University of Connecticut acknowledged as the root cause of obesity, diabetes, and other health complications at the recent American Society of Bariatric Physicians obesity conference I attended in Nashville, Tennessee).

The working theory behind increased insulin levels and blood pressure is that hyperinsulinemia strikes a chord in the central nervous system which then in turn makes the heart rate rise and other physical reactions which lead to the spike in blood pressure.

In light of this, wouldn't it seem logical to simply avoid a high-carb diet? What's wrong with making a recommendation like this to people rather than telling them to stop eating salt?

Whatever happened to just plain common sense anymore?

Labels: blood pressure, DASH, diet, high-carb, high-fat, hyperinsulinemia, insulin, low-carb, low-fat, Meena Shah, research, study

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