Women who take antibiotics over a long period of time are at increased risk of heart attack or stroke, according to a study* published in the European Heart Journal.
The study is the largest prospective study to investigate the link between antibiotic use and risk of heart disease and stroke and found that women aged 60 or older who took antibiotics for two months or more had the greatest risk of cardiovascular disease, but long duration of antibiotic use was also associated with an increased risk if taken during middle age (aged 40-59). The researchers could find no increased risk from antibiotic use by younger adults aged between 20-39.
The researchers looked at 36,429 women who took part in the Nurses’ Health Study between 2004 and June 2012.
In 2004 the women were aged 60 or older, and they were asked about their use of antibiotics when they were young (20-39), middle-aged (40-59) or older (60 and older). The researchers categorised them into four groups: those who had never taken antibiotics, those who had taken them for time periods of less than 15 days, 15 days to two months, or for two months or longer.
During an average follow-up period of nearly eight years, during which time the women continued to complete questionnaires every two years, 1056 participants developed cardiovascular disease.
After adjustments for factors that could influence cardiovascular risk, such as age, race, sex, diet and lifestyle, reasons for antibiotic use, overweight or obesity, other diseases and medication use, the researchers found that women who used antibiotics for periods of two months or longer in late adulthood were 32% more likely to develop cardiovascular disease than women who did not use antibiotics. Women who took antibiotics for longer than two months in middle age had a 28% increased risk compared to women who did not.
The findings indicate that among women who take antibiotics for two months or more in late adulthood, six women per 1,000 would develop a cardiovascular disease, compared to three per 1,000 among women who had not taken antibiotics.
Professor Lu Qi, director of the Tulane University Obesity Research Centre, Tulane University, New Orleans, and adjunct professor of nutrition at Harvard T.C. Chan School of Public Health, Boston, USA, who led the research, said that a possible reason why antibiotic use is linked to an increased risk of cardiovascular disease is because antibiotics alter the balance of the micro-environment in the gut, destroying “good” probiotic bacteria and increasing the prevalence of viruses, bacteria or other micro-organisms that can cause disease.
“Antibiotic use is the most critical factor in altering the balance of microorganisms in the gut. Previous studies have shown a link between alterations in the microbiotic environment of the gut and inflammation and narrowing of the blood vessels, stroke and heart disease,” he said.
He added: “Our study suggests that antibiotics should be used only when they are absolutely needed. Considering the potentially cumulative adverse effects, the shorter time of antibiotic use the better.”
*Yoriko Heianza, Yan Zheng, Wenjie Ma, et al. Duration and life-stage of antibiotic use and risk of cardiovascular events in women. European Heart Journal, 24 April 2019, DOI:10.1093/eurheartj/ehz231