Fasting during Ramadan is safe and may lower blood pressure – at least temporarily – for both healthy people and those with hypertension.

These are the findings of the LORANS study (London Ramadan Study) by Imperial College London researchers and published in the Journal of the American Heart Association . LORANS combines a review of existing studies of blood pressure during and after religious fasting in Ramadan, and an observational study of 85 people fasting during Ramadan.

“Despite key differences, the effect of Ramadan fasting is comparable to the effect that we saw in some papers published on intermittent fasting" Dr Rami Al-Jafar, School of Public Health at Imperial College London

Ramadan is the ninth month of the Islamic calendar and is celebrated, in part, by fasting from sunrise to sunset. Hundreds of millions of Muslims worldwide take part.

The researchers say that temporarily fasting may be a safe and effective way to temporarily lower blood pressure, but further research is needed to determine if regular fasting is effective on a longer-term basis.

“Despite key differences, the effect of Ramadan fasting is comparable to the effect that we saw in some papers published on intermittent fasting,” said study author Dr Rami Al-Jafar from the School of Public Health at Imperial. “Fasting could be beneficial for people who suffer from hypertension as well.”

Blood pressure reductions

The researchers evaluated 85 participants between the ages of 29 and 61 from five mosques in London, measuring their systolic (the top number) and diastolic (the bottom number) blood pressure before and after Ramadan. They also asked the participants to keep food diaries for three days before and during Ramadan.

For the second part of their study, the researchers combined results of 33 studies (including 3,213 people) conducted in Iran, Pakistan and Turkey, looking at blood pressure before and after Ramadan fasting.

In the 85 people from London, the study found an average reduction of 7.29 mm Hg in systolic blood pressure and 3.42 mm Hg in diastolic blood pressure in the days after Ramadan. In the review of other studies, the researchers found reductions of 3.19 mm Hg in systolic blood pressure and of 2.26 mm Hg in diastolic blood pressure.

These results were the same when they took into account changes in weight, total body water and fat mass after Ramadan. Moreover, the reduction in blood pressure was not only observed in healthy people, but also in those with high blood pressure and diabetes.

In subgroup analyses, greater blood pressure reductions were observed in the groups who were healthy or had hypertension or diabetes, but not in people with chronic kidney disease.

Health effects

Dr Al-Jafar and his colleagues speculate that the reductions in blood pressure are a result of a metabolic change that happens after eight to 12 hours of fasting when the body begins burning ketones rather than glycogen. Change in gut flora during Ramadan is another possibility.

Prior studies have suggested that calorie restriction can improve cardiovascular risk factors, as well as insulin sensitivity.

The next stages of the research will study how fasting affected participants’ weight and metabolites to estimate other health effects of fasting.

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‘ Effect of Religious Fasting in Ramadan on Blood Pressure: Results From LORANS (London Ramadan Study) and a Meta-Analysis ' by Rami Al-Jafar et al is published in the Journal of the American Heart Association.