(RxWiki News) Bacon, cheese, a ribeye, whole cream in your coffee and as many eggs as you can eat. Sound familiar? Then you've probably tried Atkins, South Beach, paleo or similar diets.
The question that has plagued researchers for decades is whether this type of low carbohydrate, high protein diet is healthy and what its short-term and long-term risks and benefits may be.
A recent study has found a mildly increased risk of cardiovascular disease in women whose diet primarily includes a lot of protein and few carbohydrates, a ratio familiar to followers of diets such as Atkins and South Beach.
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Pagona Lagiou, PhD, a professor who works both in Epidemiology and Medical Statistics at the University of Athens Medical School in Greece and at the Harvard School of Public Health's Department of Epidemiology, led a study in Sweden to assess possible cardiovascular risks from these low carb, high protein diets.
They found that a diet comprised mainly of a lot of protein and with few carbs was associated with about four to five additional cardiovascular events, such as heart disease or a stroke, for every 10,000 women.
The risk is small, and the nature of the study makes it impossible to state that the diet caused the cardiovascular conditions in women.
Further, the author states that the study could not address possible benefits of doing a low-carb, high-protein diet in the short-term to lose weight or normalize insulin resistance.
They used a random selection of 43,396 Swedish women from age 30 to 49 who were tracked for an average of 15 years, starting in 1991 and 1992. The women filled out extensive dietary questionnaires at the start of the study that also asked questions about lifestyle habits, physical activity and health history.
The dietary questions asked about their intake of 80 different foods and drinks over the six-month period before the study began. These 80 items were grouped into 11 food groups: vegetables, legumes, fruits and nuts, dairy products, cereals, meat products, seafood, potatoes, eggs, sugars/sweets and non-alcoholic drinks.
They found that 1,270, or about 3 percent, of the women experienced a cardiovascular event. About half (55 percent) had heart disease, and 23 percent had a stroke caused by reduced blood supply to the heart.
Another 6 percent had a stroke caused by a burst blood vessel in the brain, and 6 percent had peripheral arterial disease, in which plaque builds up in the arteries of the body. Ten percent had subarachnoid hemorrhage, which involves bleeding in the brain.
The likelihood of a woman experiencing one of these events increased slightly with her "low carbohydrate-high protein" (LCHP) score, which was calculated on a scale of 2 to 20: low numbers referred to diets high in carbs, low in protein; high numbers meant low in carbs, high in protein.
After taking into account lifestyle factors and health histories that relate to cardiovascular risk - such as high blood pressure, smoking, alcohol consumption, fat intake and amount of exercise - the researchers determined that every 2 points on the LCHP scale translated to about a 5 percent increase in cardiovascular risk.
Those 2 points represented approximately 20g fewer of carbohydrates a day (about one piece of bread) and 5g more of protein a day (about one egg).
The researchers said that high protein in and of itself is not bad. In fact, extra nuts and protein-filled legumes and beans can be healthy.
Sarah Samaan, MD, a cardiologist with Legacy Heart Center in the Dallas/Fort Worth area, said she has discouraged her patients from following high fat, low carb diets.
"We know that complex carbs, such as whole grains and brightly colored fruits and vegetables, provide a wide range of antioxidants that are critical to the health of the heart and brain, as well as other organs, including the digestive tract," she said. "By severely restricting carbohydrates, we deprive ourselves of these naturally healing substances."
Dr. Samaan, also the co-director of the Women’s Cardiovascular Institute at the Baylor Heart Hospital in Plano, Texas, pointed out that simple carbs like white rice, white pasta, white bread and white potatoes can cause high blood sugar, high blood pressure and an increased appetite and are "counterproductive to good heart health." But most high protein diets involve eating too much fat, especially the saturated fats in meat.
"When these fats reach the blood stream, they can create havoc by increasing the risk of blood clots, causing constriction of blood vessels, and increasing blood levels of inflammation, which can be directly toxic to the walls of the arteries," Dr. Samaan said. "All of these things increase the odds of a heart attacks or stroke."
And the antidote? Some of the very foods that people on low-carb diets are discouraged to eat.
"Antioxidants from fruits, veggies, and whole grains can help to counteract these effects, but if we're restricting these foods, then there are not enough of the "good guys" to go around and sop up those damaging chemicals," Dr. Samaan said. "By eliminating good carbs such as apples and oats, we also lose their natural cholesterol-lowering effects."
The researchers wrote that it's partly the lack of attention to which proteins and carbs a person is (or isn't) consuming that may be contributing to the small increases in cardiovascular risk.
"Low carbohydrate-high protein diets, used on a regular basis and without consideration of the nature of carbohydrates or the source of proteins, are associated with increased risk of cardiovascular disease," they concluded.
The study was published June 26 in BMJ. The research was funded by the Swedish Cancer Society and the Swedish Research Council. The researchers declared no financial conflicts or interest or other disclosures.
