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Low Carb Diets Reduce Blood Pressure

A new study suggests Dr. Atkins was right: A high carb diet is not a healthy diet, and cutting carbs trims more than just your waistline. While both low-carb and low-fat diets can help you loose weight, Duke University’s well-designed study makes it pretty clear that if you want to reduce your weight and your pressure, a low-carb diet is a better choice.

From Today’s Medscape Family Medicine:

“January 25, 2010 (Durham, North Carolina) — A new randomized trial comparing a low-carbohydrate diet with a low-fat diet in combination with the weight-loss drug orlistat has found that both strategies produced meaningful weight loss among hospital outpatients over a one-year period. Strikingly, however, the low-carb diet appeared to produce significant improvements in blood pressure.

According to Dr William S Yancy Jr (Duke University, Durham, NC), lead author on the study, this is the first time the low-carb diet has been pitted against a diet drug in combination with a different diet.”

Why is low-carb better? Deep Nutrition offers the reasons:

Carbs are nothing more than sugar molecules linked together. So after a bowl of pasta or a sack of potato chips, blood sugar levels go up until the pancreas squirts out insulin to bring the sugar level back down. Even in a healthy person (with no diabetes) every bolus of carb dropped into your tummy will lead to a brief period of time where your blood sugar is higher than optimal. In this study, done on people with high blood pressure (who tend to also be insulin resistant or diabetic) that time period is extended because it takes longer for the body to respond to insulin.

And why is high blood sugar bad?

This is a basic question, and, as it turns out, answering this simple question yields an abundance of explanations for all sorts of diseases (covered in chapter 9 of the book). Today’s discussion will focus on the effects of high blood sugar on arterial flexibility.

How Sugar Affects Your Body: Understanding the Maillard reaction

Sugar spontaneously sticks to proteins. This reaction is the result of a biochemical reaction known as the Maillard reaction. It explains why sugary foods like jelly and ice cream feel sticky when they dry on our skin. You can see the Maillard reaction at work when you roast a chicken. In the hot oven, sugar molecules and proteins present within the skin of the chicken react together much faster than at room temperature (or the body temperature of a chicken). The result of all these trillions of Maillard reactions is a delicious crispy skin.

The bottom of the pan, however, often ends up coated with a black sticky gunk. On a high-carb diet, a similar sticky gunk can form inside the backbone of your arteries, leading to high blood pressure.

It works like this:

At normal blood sugar levels, Maillard reactions occur at a slow and steady rate. A healthy body has systems in place to clean up the few molecules of yucky sticky gunk that form. At higher-than-normal blood sugar levels, Maillard reactions start to accellerate, and sticky gunk builds up faster than the body can clean it up. Over years, the sticky gunk accumulates, leading to test results that draw a doctor’s attention.

Maillard reactions in your arteries can affect your blood pressure.

On a high carb diet, your arteries are bathed in glucose molecules on a regular basis. Glucose molecules react with proteins in your arteries, basically slow cooking them right inside your body.

While sticky gunk buildup in the supporting proteins of your arteries doesn’t make them quite as crispy as roast chicken skin (because the conditions are less drying inside your arteries than in an oven), arteries afflicted with sticky gunk products of Maillard reactions are going to be stiffer than normal. This is not good for your circulatory system. (Are you surprised?) When arteries loose their compliance and flexibility, it’s harder to pump blood through them. That means your heart has to pump harder and your blood pressure rises.

With so many people eating more carbs than they should, it’s little wonder that the NIH reports 90 percent of people over the age of 65 now have high blood pressure.

Antioxidants like vitamins and flavinoids in fresh vegetables slow down the rate of the Maillard reaction, which is why studies keep showing that fresh vegetables and antioxidants are good for us.

Doctor’s advice: If you want to get off your pressure pills, the first step is to cut your carbs! While this study was done on overweight people, I’m pretty sure in time we’ll see studies that show low carb diets reduce pressure no matter your weight. So keeping your total daily pasta, bread, potato, rice, fruit, and other carb-rich food consumption under 100 gm (or 3 oz) per day is a great long-term goal.

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Dr. Cate


  • Crystie

    Dr. Cate,

    Could this also result in low blood pressure? Mine has always been low, and I’ve often felt lethargic. When I exercise, it’s like my blood can’t keep up. When I was in the army, my blood pressure was usually 75/60. And exercise left me very cold.

    I have often been anemic. And in previous years (including the army ones) I was trying to live off cereal.

    Any way, my sister and I were discussing PUFAs and sugar, and wondering if low blood pressure is a problem, and if it could be caused by these things.

    • http://drcate/com Dr. Cate

      Low blood pressure is not a problem. Mine is 90/50. Lower is better because it means less stress on your entire system.

  • Claudia Ayers

    Thanks Ruth, this was very, very informative video… it covered a lot of ground. However, Dr Baylock says a few things I question: I think he gives milk a bad rap based on results that probably related to low-fat industrial products that are not at all as valuable as raw milk. Same for animal fats… I now eat QUALITY animal fats… while the feed-lot fats (from animals that eat corn and soy) ARE bad for you, quality fats are GOOD for you. Dr. Cate explains it well in her book!

  • Ruth M

    Dr. Cate –

    I just saw this neat video yesterday of a talk by neurosurgeon, Dr. Russell Blaylock on the impact on behavior of blood sugar levels. Thought you might want to see it.

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