Like immigrant Indians, Japanese immigrants living in the U.S. have a higher mortality rate from heart disease than those living in Japan. Traditionally, the Japanese were believed to have superior genetics with respect to heart disease (since Japan has the highest number of centenarians alive) but all this genetic superiority disappears when they start living abroad, even as they continue to consume their traditional diet. This phenomenon is not only true for immigrants living in the U.S. but for immigrants all over the globe. The same has been found true of Indian immigrants living in Singapore, compared to Singapore natives. A study done in the 1990 found, “the higher mortality from ischemic heart disease found in Indians in Singapore cannot be explained by the major risk factors of cigarette smoking, blood pressure and serum cholesterol.”

Compared to Singapore natives, the immigrants smoked less, had lower blood pressure and cholesterol, and yet – counter intuitively – their mortality rate was higher. The same study also noted that the immigrants had a higher incidence of diabetes.

A meta-analysis of 58 studies (published between 1986 and 2008) relating to deaths from myocardial infraction (MI) among first generation immigrant populations worldwide found, “there was an overall trend for increasing risk of MI among immigrants worldwide.”

Another meta-analysis of 23 studies of immigrant populations in Australia sought the answer to this question: Is being an immigrant a heart disease risk factor? They concluded, “higher prevalence of cardio vascular disease was found among Middle Eastern, South Asian and some European immigrants.”

In another remarkable study done in London, 364 participants were divided into two groups where one group was first generation immigrants living in London, and the other group was their siblings living in Punjab. This eliminated any genetic or hereditary factors from corrupting the results. It was found that the London immigrants had higher BMI, BP and insulin resistance compared to their siblings in India, putting them at a higher risk of heart disease.

The same is true for Bangladeshis living in London, who in spite of having lower cholesterol, eating a lower-fat diet, and smoking less, were found to have higher mortality rate from heart disease compared to the English residents of London.

So the natural question is, what makes immigrant populations more susceptible to heart disease? And the answer to this is, stress.

What is stress?

It is any internal or external state of disharmony that consistently challenges either our physical or emotional integrity. Daily stress is an inseparable part of our lives. In the daily hustle and bustle, we are always scrambling to compress more and more work in the 24 hours we have. The stress of a looming deadline, of paying bills, of taxes, and the stress of daily traffic are all examples of overt stresses that we all know to recognize and to cope with to a certain extent. But there are deeper subliminal stresses that work at a sub-conscious level and those are the ones that affect our health in the long run.  These are the stresses that most immigrant populations experience. The stress of social dislocation (being in a foreign land), cultural alienation, socio-economic stress, depression and anxiety are all examples of subliminal stresses that add up to chronic stress.

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So how does chronic stress impact our health? Without going into too much detail, stress causes the adrenal glands to release two distinct hormones, adrenalin and cortisol. The first, adrenalin, is linked to fight-or-flight during times of impending calamity. Someone pointing a gun at you will cause the release of adrenalin, which prepares you to either fight or run away from the stressor. This causes your heart rate and blood pressure to go up, your liver to quickly release blood sugar to power the brain and muscles for a quick reaction, and your pupils to dilate so that more light can enter your eye for better visibility. But this type of stress is momentary, and does little harm to our long-term health.

The second type of stress is the slow nagging stress of daily life, and other subliminal stresses that cause the release of cortisol, the second stress hormone. Cortisol works in the same way as adrenalin but over longer times. In a normal healthy person the primary role of cortisol is for stress response and as an anti-inflammatory agent. Cortisol also plays a role in energy metabolism by commanding the fat cells to release triglycerides, and the liver and muscles to release blood sugar.

In a healthy person, production of cortisol peaks a few hours after waking up and then tapers off during most of the day, until the evening when it peaks again. It then falls to its lowest level a few hours after sleep. In a person with chronic stress, the levels of cortisol stay high throughout the day. Just like adrenalin, cortisol increases blood sugar – but since the excess sugar is not used, it has to be stored away.

So rather than causing a net weight gain, cortisol causes weight redistribution. A simple explanation of the mechanism is that cortisol commands the peripheral fat cells (in our arms and legs) to release triglycerides into the blood stream. These triglycerides are then converted to blood sugar (in the liver) and released into the blood stream. Now insulin comes into play, and starts storing this excess sugar. Since abdominal fat cells have four times the number of insulin receptors compared to fat cells in other parts of our body, this excess sugar ends up as stored belly fat. So essentially cortisol takes fat from our arms and legs and stores it as belly fat.

That is medical fact. Cardiology studies have taken the correlation to the point of causation, and bluntly state that belly (intestinal) fat is far more likely to lead to ischemic heart disease than outer body (subcutaneous) fat.

So aside from important “incidentals” such as increased blood pressure, elevated levels of the stress hormone cortisol moves body fat from the low-risk areas of fat storage, to the more dangerous areas of intestinal fat storage – a double jeopardy for heart disease!

Being an immigrant in a foreign land subjects us to various socio-economic stresses. While we eke out better lives for ourselves, there is an underlying stress factor that we need to be aware of. Distinguishing daily stresses that can be managed with foresight and planning (like deadlines, taxes, traffic etc.) from the subliminal stresses that put us into anxiety and depression (like stress of social hierarchy, social dislocation, cultural alienation etc.) go a long way towards ensuring our good health.

As Dalai Lama rightfully says, “If a problem is fixable, if a situation is such that you can do something about it, then there is no need to worry.  If it’s not fixable, then there is no help in worrying. There is no benefit in worrying whatsoever.”

So worry less, be happier, and your heart will thank you for it.