A fascinating new study conducted by Jack Rubinstein, MD, an associate professor at the University of Cincinnati College of Medicine, has found that the act of wrapping the straps of tefillin around the arm on an almost daily basis could help prevent heart attacks. The results of the study, published last month in the American Journal of Physiology-Heart and Circulatory Physiology, could explain previous Israeli studies that found that religious men (but not women) suffered fewer heart attacks than the general population.

Twenty Jewish men living in or around Cincinnati participated in the study, including nine who wore tefillin daily and 11 who didn’t. The subjects’ measurements were taken after wearing them for 30 minutes. These included participants’ vital signs, blood analysis to detect circulating cytokines and monocyte function, as well as blood flow in the arm that wasn’t wrapped in the tefillin. The results indicated that the blood flow was better in men who wore tefillin every day, but it improved in all participants even after wearing them only once. Men who wore tefillin daily also had fewer circulating cytokines, molecules that can cause inflammation and negatively impact the heart, compared to non-users.

While those who put on tefillin on a daily basis (excluding Shabbos and Yom Tov) do so to fulfill a mitzvah, the fact that binding the arm may serve as a form of preconditioning and offer a substantial degree of protection against “acute ischemic reperfusion injury” is beyond titillating.

I spoke to Dr. Rubinstein this past Friday.

How did the idea for this research come about?

Around 30 years ago, scientists discovered that if you restrict the blood flow to any extremity in an animal or human and then they have a heart attack, the attack is less intense. This phenomenon is called RIPC (remote ischemic preconditioning), and it happens through a number of pathways. One of the key pathways – and here’s where the tefillin come in – is through the discomfort that is felt when you block off the flow to an artery. One of my mentors had previously delved into this, so I had it on my mind. Then one day when I was wearing tefillin – in an airport, of all places – I felt that discomfort and made the connection. As someone who puts on tefillin every day, I’m sure you’re familiar with the sensation that occurs after five, six or seven minutes, when you have to adjust your hand ever so slightly and maybe adjust the tightness of the straps. That feeling of discomfort got me thinking about whether this qualified as a preconditioning stimulus. That’s when the moment of clarity came, and I decided to look into it.

When you say “discomfort,” you mean that feeling in the arm due to a lack of blood flow?

I don’t know if I would call it a “lack” of blood flow, but there’s definitely a decrease. If you blocked it off completely for the 30-45 minutes of the morning service your arm would fall off, so it’s only a reduction, not a blockage.

Is there a danger of binding the tefillin too tightly?

Absolutely. We found that the way the tefillin are traditionally worn – tight, but not to the point where your arm turns purple – is just the right amount of pressure. But there is definitely a danger of tying them too tightly. You can actually make your arm fall off. This is one of the things that makes me very worried about people trying this out on their own. If you tie anything – leather straps, rubber bands, etc. – around your arm tightly enough, you can cause damage relatively quickly that can be very severe. You have to be really careful.

Can you explain to the layman how the preconditioning benefits cardiovascular health?

We know from animal studies that when we cause this discomfort in specific ways we change the way the body reacts to a heart attack. There are certain cells in our body that circle around and are primed to attack. If a person suffers a heart attack, these cells will attack the body very aggressively. It was discovered that when the animals were preconditioned and prepared for a heart attack, these cells were significantly less likely to attack. When we measured these cells in people who wear tefillin every day, they were significantly less primed to attack. That led us to believe that if these people did have heart attacks, the cells that are partially protective and also partially aggressive and harmful would be activated to a lesser degree, and therefore cause less damage to the heart.

I was aware that a heart attack cuts the flow of blood to the heart and that’s where the damage comes from. But I didn’t know that there’s something else going on at the same time.

When a person has a heart attack there are two components to the damage. The first is what you mentioned, which in medical terminology is called “ischemia.” The ischemic injury is definitely harmful, and it accounts for about 50% of the damage. We in the medical community are very good at treating that component. We can get the patient to the lab, give him medicine and restore the blood flow. But the other half of the damage that occurs is something called a “reperfusion injury,” and we aren’t so great at treating that. We believe that it’s in regard to the reperfusion injury where the tefillin are causing the improved outcomes. We don’t know yet if those people are less likely to have a heart attack, or if their heart attack will be less severe.

And this is caused by the cells you described before?

Yes. We found several different things in the study, but I’ll break it down into three big discoveries. Number one, we found that the cells were not as activated. Number two, the cytokines – the marching orders the cells receive from the body itself – were lower, meaning that they were being told to relax because everything was going to be okay. And number three, thanks to our collaboration with Dr. Elaine Urbina of Cincinnati Children’s Hospital – we found that the blood flow was better. The idea is that people who wear tefillin daily have cells that attack less and are given fewer orders to attack, and they also have better blood flow after a heart attack. These are all positive things you want in order to mitigate and reduce the reperfusion injury.

Would you say that the tefillin contribute to the healing as well?

Not necessarily to the healing, but they certainly contribute to avoiding the damage caused by the second kind of damage that happens in a heart attack. One of the reasons I got into this was that after the idea occurred to me, I went online to see if anyone else had already made the connection. To the best of my knowledge no one else had, but there’s a person in Israel who did a very comprehensive 23-year study on almost 10,000 Israeli male civil servants, which included many details of their backgrounds and activities. One of the things they asked about was religious observance, and they divided it into five levels of observance or lack thereof. They found that when taking other factors into consideration, people on all five levels died of the same things with one exception: far fewer of the most Orthodox of the men died of heart attacks. It was very difficult to understand whether they had fewer heart attacks to begin with, or there were fewer repercussions from the heart attacks. You can make the argument that our own findings could account for one or the other. It isn’t clear right now which one is true.

What about Orthodox females?

Well, this study was only conducted on males. There’s a separate paper on Orthodox kibbutzim versus non-Orthodox kibbutzim that found that fewer Orthodox males died of heart disease than non-Orthodox males, but there was no difference between the women.

That would seem to confirm your theory that it has nothing to do with living a life of faith, but with the physical act of putting on tefillin.

I wouldn’t use the word “confirm.” I’d use the word “support.” But other than that, that’s exactly correct.

So the “side effect” of putting on tefillin is a logical conclusion drawn from the other study.

Others have known about the original study, and some very smart people have done clinical trials with different devices and ways of tying off the arm, but almost none of them showed a benefit because people can’t predict when they’re going to have a heart attack. They’ve also tried various things during a heart attack, immediately following a heart attack, and during heart procedures and so on, but most of those studies haven’t yielded results. In my opinion, the key point they were missing was the pre-conditioning aspect; there has to have been a stimulus before the heart attack. I’m arguing that putting on tefillin before the heart attack confers a benefit to the sufferer. But once the heart attack begins it’s already too late to do anything because the alarm system is going off in the body. The cells are attacking and the blood vessels aren’t prepared. It’s a sneak attack.

But your premise isn’t so farfetched, because it’s essentially based on other studies.

Absolutely. It’s based on science. I stand on the shoulders of giants.

If it’s based on science, then of course tefillin would be a preconditioning stimulus.

We had to test it first to know for sure. That’s the beautiful part of science, and what I love the most about science in medicine. There’s a saying that “sometimes you have a beautiful hypothesis that’s destroyed by ugly facts.” We had to figure out how to do the tests in order to find the markers and see if it proved or disproved the hypothesis.

Couldn’t this be replicated by tying strings around the arm instead of tefillin? Is the benefit related specifically to tefillin?

The amount of pressure that is created appears to correlate very well to the wearing of tefillin for the right length of time. For example, if I had you wear a blood pressure cuff and inflate it tremendously to the point where it cut off the blood flow to the artery your arm would fall off. You need to find a fixed, limiting blood flow device, because if you do it too loosely you won’t get any benefit, and if you do it too tightly you’ll lose your arm.

Tell me about the test itself.

The way we organized it was very cool, and I give credit to Phil Owens, Mike Tranter, Marc Rothenberg and Elaine Urbina for designing the study. We didn’t have a lot of money, so we had to get the biggest bang for our buck. We wanted to test two different things: Does wearing tefillin every day help, and does wearing tefillin only a single time do the same thing? We found 20 Jewish males in the Cincinnati area and told them about our plans. To try to keep the data to a minimum, we wanted only young healthy males. We had them come in so we could check their vital signs. Then the next day we asked them to arrive before davening and breakfast so we could draw their blood to test all the things we talked about, and we also measured their blood vessels. Then we had them wear tefillin for 30 minutes and stay in a room. After they took their tefillin off, we drew their blood again and re-measured their blood flow. This way we were able to compare the baseline characteristics of people who wear tefillin every day and the people who don’t. We were also able to compare the effect of wearing tefillin only a single time and determine whether or not it would have the same effect.

What were the results?

When it comes to blood flow, there are several ways to measure it. We found that people who wear tefillin every day have a better blood flow baseline. We were able to distinguish which people were or weren’t wearing tefillin based only on that! It was a blind study, meaning that the researchers didn’t know what the participants’ individual baselines were – they were only a number to them – so that way no one could cheat. Additionally, we found that after the tefillin were worn only once, the blood flow improved right away in some parameters, although not in all of them.

When it came to the attacking monocyte cells, we measured how quickly they moved or migrated and how sticky they were. If you think of them as soldiers, we were looking at how quick they were to react and how aggressive they were once they reached their destination. The people who wore tefillin daily had monocyte cells that were significantly less sticky and aggressive. And their marching orders, meaning the molecules that the body produces to tell them to attack, were significantly lower in the people who wore tefillin daily versus the ones who didn’t. However, those who wore tefillin only once didn’t experience a change in this area. There were a couple of small changes here and there, but by and large there was no difference. We had four different associated labs working on this study. Each one conducted its research in different ways and they were all blinded, so there was no way that anyone could manipulate the data.

How much better were the tefillin wearers than the non-tefillin wearers?

It depends on which variable you look at. With some variables the difference was between 5% and 15%. The biggest difference we found was that even wearing tefillin only a single time caused the brachial artery in the arm to double in size. Some of the molecular and cell-based data increased twofold, and sometimes even threefold and fourfold depending on what we were looking at. In general the differences ranged from 10% to 400% depending on what we were measuring.

Wouldn’t you also have to consider the amount of time the tefillin were worn? You’re using a half hour as a baseline, but some people might wear them for only a few minutes while others keep them on longer. Were those variables taken into consideration, or is that something you intend to look at in the future?

In this particular study the subjects wore them for 30 minutes, because in the original Israeli study they found that the only people to derive benefit were the fully Orthodox, not those who were only traditional but still wearing tefillin. We decided that the difference had to be in the amount of time the tefillin were worn. Traditional people who wear tefillin usually wear them for five minutes, say Shema and then move on. By contrast, Orthodox Jews tend to wear them while davening the whole Shacharis, which on average takes around 30 minutes.

So you believe that there’s a difference between wearing tefillin five minutes a day and 30 minutes a day.

Correct, and that’s based on the 10,000-patient study.

But you haven’t determined the actual difference because you just haven’t gotten around to it yet?

There are so many great questions we still have to ask. I was speaking with a couple of researchers, including one out of Boston who is in charge of an initiative in Harvard on religion and health. He brought up a lot of similar questions. A lot of them could have really interesting clinical applications but unfortunately these aren’t the cheapest studies to do, so my next task is to try to track down funding sources.

Did you test people who put on tefillin who suffered heart attacks to see how their recovery went?

No. That’s the next step. One of the reasons I chose to issue a press release was that we need funds to do research into the next series of questions: What happens to people who have had heart attacks? What happens to women? What if we control for the davening? What if we control for the social aspect?

Most people wear their tefillin on their left arm, but lefties wear it on their right. Would there be a difference between the two?

I hope to do that study at some point, but if I had to guess I’d say no. The idea we have right now is that the discomfort and partial blockage of blood flow is what causes this effect, so I would think that both right and left would be the same, but I don’t have data to support it.

I guess you didn’t ask the participants which hand they wore their tefillin on.

We did, but all but one wore it on the left.

So we don’t know the answer to that question at this point in time.

No. Hopefully I’ll get the funding that will allow me to keep asking these questions and answering them.

When was your study concluded?

We recruited patients in 2016 and 2017, and the results were published a week or two ago.

Did it go through peer review and all that?

Of course. It went through very strict peer review. The journal in which it was published is very prestigious. The American Journal of Physiology has been around for many decades and is very well respected in the medical community. It was reviewed by four different researchers, and we went back and forth with them to make sure that everything was correct and that their conclusion was appropriate.

Are you a researcher or do you practice medicine?

Both. I’m a scientist and a clinician. Half of my day is taken up by research and the other half is devoted to taking care of patients.

What’s your specialty?

I’m a cardiologist.

Where did you earn your medical degree?

I’m from Mexico, and I got my degree from a medical school in Mexico City.

So you’re bilingual.

After 15 years in the US I think my English is better than my Spanish, but I’m fluent in both and I’m also okay with Hebrew.

I’m sure that this has influenced the way you look at Orthodox patients. Have you considered telling people who don’t wear tefillin to start wearing them?

Before I suggested such a thing I would need to do more testing. This is pilot information. It does happen to be consistent with my original hypothesis, which is rare in science – a hypothesis doesn’t usually turn out to be correct – but I wouldn’t tell people who don’t otherwise wear tefillin to start donning them for their heart. But it does provide food for thought.

I’m assuming that there would be people in Israel who might be interested in funding something like this. Maybe even one of the major hospitals.

I spoke to someone in Israel, and we even submitted a proposal through something called the Binational Science Foundation, which is a collaborative effort between Israel and the US for the promotion of science. Unfortunately, we didn’t receive the funding. We’re going to keep on trying, but if there’s someone in Israel who is willing to run with this we’d be thrilled to work with him. I’ve reached out to some fundraisers, but I haven’t gotten a lot of traction.

I know that science is supposed to be about cold, hard facts, but did this discovery have any emotional or spiritual impact on you?

It did. I’ve been struggling with religion my whole life, and this definitely gave me pause, although not in a direct action kind of way; it had more to do with thinking about the big picture. Science and medicine cannot consist of only cold, hard facts. We are humans, emotional and spiritual beings. I’m still grappling with the full implications.

You must have realized from the get-go that this wouldn’t be solely a scientific study because of the religious implications, and that it would have an emotional effect on people.

I did. It’s interesting to see people reacting to this from all different camps. It could be one of those things where science and religion bring people together rather than the opposite.

This article originally appeared in Ami Magazine.