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Low-Carb Diets Impair Blood Flow

Low-Carb Diets Impair Blood Flow

Low-carb, high-protein diets such as the Paleo or Zone diet, have become very popular, especially among many fitness-minded groups such as CrossFit. To their credit, low-carb diets such as the Paleo diet eschews dairy, refined foods, and added sugars/salts, although they severely limit complex carbohydrates which are the primary component of a whole-food, Starch-Smart® diet. Supporters of low-carb diets obtain the majority of their calories from animal protein and fat. No other diet has generated as much emotion or controversy as these low-carb diets have.  (Information regarding whole grains can be seen here.)

Historically, these diets follow an endless cycle. Opponents believe that these diets are just a refurbished version of the dated Atkins diet. As science confirms the adverse effects from these diets, periodic revision is required every few years to make these same disease-promoting high-fat plans more trendy and attractive. Most low-carbers would agree, that no amount of science would persuade them to switch to a low-fat, plant-based diet. Ultimately, it comes down to taste preference, convenience, and one's voracious addiction to high-fat foods that drives appetites, not science. Eventually though, these "new and improved" low-carb diets will fail to be supported in the scientific literature.  

Of course, all diets (plant-based diets included) publicize their health benefits, asserting a cure for every known affliction. However, our nation's leading nutritional experts, scientists, top surgeons, researchers and plant-based physicians have conducted many groundbreaking studies over the past 30+ years. The scientific literature convincingly demonstrates disease prevention and reversal in those people groups that consume diets predominantly of whole plant foods. Low-carb followers eagerly cite recent studies which support their position regarding saturated animal fats. The results from these studies can be easily explained when the data is thoroughly examined. Dr. John McDougall  responds to these claims by saying, "People love to hear good news about their bad habits. They ignore the bulk of the science, exaggerate the truth, and make false associations."  

Dr. Michael Greger's video below demonstrates "the impact of low carb diets on arteries directly." A review of all the studies to date "found that low-carb diets impair arterial function, as evidenced by a decrease in flow-mediated dilation, meaning low carb diets effectively stiffen people's arteries."

As you will see in this video, a commonly noted benefit of going low-carb is a temporary reduction of cholesterol levels. Yet how is that possible? According to Dr. Greger, "Weight loss by any means can drop your cholesterol. You could go on an all-Twinkie diet and lower your cholesterol if you were unable to eat the dozen daily Twinkies necessary to maintain your weight." He goes on to mention that illegal drugs, chemotherapy and tuberculosis lowers cholesterol and produces weight loss as well. "Anything that drops your weight can drop your 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."

We now have a tangible study that measured and recorded "actual blood flow to the heart muscles of people eating low carb diets." Dr. Richard Fleming, "an accomplished nuclear cardiologist, enrolled 26 people into a comprehensive study of the effects of diet on cardiac function using the latest in nuclear imaging technology--so-called SPECT scans, enabling him to actually directly measure the blood flow within the coronary arteries." Those patients which followed the healthy vegetarian diet "showed a reversal of their heart disease as expected. Their partially clogged arteries literally got cleaned out. They had 20% less atherosclerotic plaque in their arteries at the end of the year than at the beginning." The health of those patients that followed a low-carb, high-animal protein diet "significantly worsened." Scans showed they had "40 to 50% more artery clogging at the end of the year."  

You'll notice in the video how the arteries opened up which increased the flow of blood to the heart muscle in the patient that followed a plant-based diet. The patient who followed the low-carb diet however, had significantly clogged their arteries and impaired blood flow. These scans are similar to the ones published in Dr. Caldwell Esselstyn's book, Prevent and Reverse Heart Disease. (Scroll through the photos.)

Although this is the best comparison study we have to date which actually measures the flow of blood in patient's hearts who eat different diets, 40+ years of nutritional research affirms that diets high in animal fats are associated with significantly higher morbidity rates and all-cause mortality. Low-carb advocates such as Dr. Robert Atkins and former Weston Price Board of Directors member Stephen Byrnes, both experienced the consequences from following their own recommended diets. Stephen Byrnes, who enjoyed a diet including "butter, cream, eggs, meat, whole milk, dairy products and organ meats suffered a fatal stroke before he reached his 40th birthday." Dr. Robert Atkins had a medical history which included a myocardial infarction, congestive heart failure, and hypertension. At the time of his death, his wife declined an autopsy and insisted that his death had nothing to do with the condition of his heart. On the other hand, Nathan Pritikin, who founded the Pritikin Longevity Center near Miami, Florida successfully reversed his heart disease, (using a plant-based diet) which was proven following his death. Preceeding his death, he had arranged for a thorough autopsy to be performed. The autopsy revealed that his coronary arteries were completely clean despite his significant heart disease diagnosed in his forties. His results were published in the New England Journal of Medicine.

For more information regarding low-carb diets and heart disease, click on the following links:

(1)  "Animal-Based Diet Turns Our Blood Fatty"

(2)  "Nathan Pritikin Shows Heart Disease is Reversible"

(3)  "How Bad Can Just One Meal Be?"

(4)  "The Paleo Diet Is Uncivilized"

(5)  "Diet Linked to Heart Disease Reduction During War"

(6)  "Low Carbohydrate Diets are Unhealthy and Dangerous" 

(7)  "The Leaky Gut Theory of Why Animal Products Cause Inflammation" 

(8)  "The Atkins Scientific Research – Deceit and Disappointment"

(9)  PubMed - "Effect of a single high-fat meal on endothelial function in healthy subjects"

(10)  "Low-Carb vs Plant-Based" video comparison of diet book authors 

Michael Greger MD Links

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