Fresh research offers further information on the potential for diet drinks — that is, beverages sweetened with artificial sugar substitutes — to harm cardiovascular health.

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Artificially sweetened soft drinks may raise the risk of heart disease and death in postmenopausal women.

A study that followed tens of thousands of postmenopausal women for more than 10 years has linked a higher consumption of diet drinks to an increased risk of stroke, heart disease, and death.

The link between diet drinks and stroke was strongest for strokes that arise from blocked arteries, and from smaller blood vessels in particular.

The journal Stroke has now published a paper about the analysis. The lead author is Dr. Yasmin Mossavar-Rahmani, an associate professor of clinical epidemiology and population health in the Albert Einstein College of Medicine in the Bronx, NY.

Dr. Mossavar-Rahmani and her team point out that the findings do not prove that diet drinks harm the heart and circulation system. That is because the study was an observational one, and the figures on diet drink consumption came from self-reports.

However, Rachel K. Johnson — who chaired the panel that wrote the science advisory from the American Heart Association (AHA) about diet drinks and heart health — comments, "This study adds to the evidence that limiting use of diet beverages is the most prudent thing to do for your health."

Experts commenting in an editorial that accompanies the new study paper also suggest that until there is sufficient evidence regarding who might benefit from consuming diet drinks, the emphasis should be on drinking water as the most healthful no-calorie drink.

Diet drinks and cardiovascular risks

The data for this study came from a racially diverse group of 81,714 postmenopausal women in the Women's Health Initiative Observational Study.

The women were all aged 50–79 years when they enrolled during 1993–1998. The study then tracked their health with regular evaluations for an average of 11.9 years afterward.

At the 3-year evaluation point, the women answered some questions regarding how often they had consumed diet drinks in the previous 3 months.

The researchers defined diet drinks as any low-calorie colas, soda, and fruit drinks sweetened with artificial sugar substitutes.

They did not ask the women to specify the which artificial sweeteners the drinks contained.

When they analyzed the data, they adjusted the results to eliminate the effect of other factors that influence stroke risk, such as age, smoking, and high blood pressure.

The researchers found that compared with consuming fewer than one diet drink per week or none at all, consuming two or more per day was associated with:

    • a 23 percent raised risk of stroke
    • a 31 percent higher risk of a stroke that results from a clot
    • a 29 percent higher risk of heart disease, as in a fatal or nonfatal heart attack
    • a 16 percent raised risk of death from any cause

    They also revealed that a high intake of diet drinks among postmenopausal women with no history of heart disease or diabetes was linked to a more than twofold raised risk of strokes arising from blockages in small arteries in the brain.

    Postmenopausal women with obesity who drank two or more diet drinks each day also had twice the risk of stroke than those who drank fewer than one per week.

    'Limit prolonged use of diet drinks'

    Because they confined the study to postmenopausal women, the researchers cannot say whether the same would be true for men, or for women before menopause. It is now up to further studies to determine this.

    Also, because the data did not specify which artificial sweeteners the women had consumed, Dr. Mossavar-Rahmani says that the scientists could not distinguish the potentially harmful from the potentially harmless.

    "Our research and other observational studies have shown that artificially sweetened beverages may not be harmless and high consumption is associated with a higher risk of stroke and heart disease."

    Dr. Yasmin Mossavar-Rahmani

    While the AHA advise that people drink water as their preferred no-calorie drink, they acknowledge that diet drinks might help them move away from sugar-sweetened beverages.

    However, Dr. Johnson cautions, "Since long-term clinical trial data are not available on the effects of low-calorie sweetened drinks and cardiovascular health, given their lack of nutritional value, it may be prudent to limit their prolonged use."