A study performed by the University of Cincinnati College of Medicine on 20 Jewish men has discovered that putting on tefillin daily, for a duration of 30 minutes each day, has cardiovascular health benefits.

Dr. Jack Rubinstein led the research group and gather 20 Jewish men for the study - 9 who don tefillin daily and 11 who do not. All the men were in good health and between the ages of 18 and 40. They recorded baseline information of the participants and then again more data after laying the tefillin for 30 minutes.

To quote:

The usage of tefillin, also called phylacteries, dates back to scriptural commandments in the books of Deuteronomy and Exodus urging the faithful followers to comply with religious law and to "bind them as a sign upon your arm.” Rubinstein says the binding of the arm and the discomfort users often report may serve as a form preconditioning and offer a substantial degree of protection against acute ischemic reperfusion injury (a section of the heart is deprived of oxygen and then damaged when re-oxygenated) that occurs as a result of a heart attack.
"One of the ways that protection occurs is through pain,” says Rubinstein, also a member of the UC Heart, Lung and Vascular Institute. "Feeling pain is actually a preconditioning stimulus.
"We found people who wear tefillin in either the short or long term, recorded a measureable positive effect on their blood flow. That has been associated with better outcomes in heart disease,” says Rubinstein.
Blood flow was higher for men who wore tefillin daily and improved in all participants after wearing it just once as part of the study, explained Rubinstein. Men who wore tefillin daily also had fewer circulating cytokines—signaling molecules that can cause inflammation and negatively impact the heart—compared to non-users, suggesting that near daily use elicits an effect similar to that observed with other methods of eliciting remote ischemic preconditioning-like effect.
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Rubinstein says there are studies out of Israel that have found Orthodox men have a lower risk of dying of heart disease compared to non-Orthodox men. This protection is not found in Orthodox women who usually don’t wear tefillin.

There you have it. Wearing tefillin daily makes your blood flow better.