Even though the actual numbers are small (an additional four to five cases of cardiovascular disease per 10,000 women per year compared with those who did not regularly eat a low-carbohydrate, high-protein diet), this represents a 28% increase in the number of cases.
Women often consume diets that are high in protein and low in carbohydrates, such as the Atkins diet, in order to manage their weight.
Although several studies have been conducted on the long term consequences of these diets on cardiovascular health, their results have been conflicting.
As a result, a team of researchers conducted a study of more than 43,000 women in Sweden. The participants, who were assessed over 15 years, were aged between 30 and 49 years from 1991-1992.
Study participants were asked to fill out a dietary and lifestyle questionnaire. In addition, diet was measured on the low carbohydrate-high protein (LCHP) score; a score of 2-19 represented a high intake of carbohydrates and low intake of protein, and a score of 20 represented a low intake of carbohydrates and high intake of protein.
The researchers took into account factors, such as alcohol use, smoking, overall level of activity, diagnosis of hypertension, and saturated/unsaturated fat intake, all of which were likely to influence the results.
Over the 15 years, the team found that 1,270 participants had suffered a cardiovascular event:
- 55% ischemic heart disease
- 23% ischemic stroke
- 6% hemorrhagic stroke
- 10% subarachnoid hemorrhage
- 6% peripheral arterial disease
They found that risk of cardiovascular disease increased by:
- 13% for women who scored 7 to 9
- 23% for those who scored 10 to 12
- 54% for women who scored 13 to 15
- 60% for those who scored 16+
Increasing levels of smoking was found to increase the risk of cardiovascular disease, whilst increasing level of education and physical activity reduced the risk.
According to the researchers, LCHP diets "used on a regular basis and without consideration of the nature of carbohydrates or the source of proteins are associated with cardiovascular risk."
They note that further studies are required in order to examine the possible benefit of short-term effects of LCHP diets that can be used to control weight or insulin resistance.
In an associated report, Anna Floegel from the German Institute of Human Nutrition and Tobias Pischon from the Max Delbrück Center for Molecular Medicine in Germany, explains that the short term benefits of weight loss seem outweighed by longer term cardiovascular harms.
In addition, she states that the conflicting results from different types of studies in this field "need to be resolved before low carbohydrate-high protein diets can be safely recommended to patients."
In the meantime, they indicate that any benefits gained from these diets in the short-term "seem irrelevant in the face of increasing evidence of higher morbidity and mortality from cardiovascular diseases in the long term."