INDIANS & HEART DISEASE - Nature or nurture? (by Sandra Davie)

The following is from a report by Sandra Davie, Senior Writer in of Saturday Special Report of the Straits Times dated 27 February 2010, Saturday.
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HE RUNS scared, every other evening, an hour, or even two. He pounds the 10km route near his HDB home in Bukit Merah, his T-shirt sweat-soaked.

It's not about staying fit but about staying alive. It's about fending off the heart disease that Mr Maverick Saravanamuthu knows lurks everywhere in his family history.

The runs and three intense workouts a week at the Science Park's Fitness Network gym are just two of the weapons in his armoury to help him defy the fate his genes and race may have in store for him.

Diet is another. Fatty foods and processed carbohydrates, including his favourite roti prata with egg, are out. Greens are in. He is 1.63m tall and maintains his weight at a constant 61kg. He goes for medical screenings twice a year to ensure his cholesterol, glucose and blood pressure remain at healthy levels.

The 41-year-old, who runs a firm that organises health talks and workshops, knows that the risk of contracting heart disease and any one of the host of related ailments, such as hypertension or diabetes, hangs over him like the Sword of Damocles.

His father, despite practising yoga regularly, developed diabetes in his early 30s and suffered his first heart attack at 35. His second, a massive one at 62, killed him.

His mother, now in her 60s, had a heart attack six years ago and a bypass operation. One of his two sisters, now 45, is exhibiting risk factors and has mild hypertension and diabetes.

Being in the health-related business, Mr Maverick, who married at age 33 and has two young children, is only too aware that heart disease strikes Indians more frequently, at an earlier age, and more severely than all other races in Singapore.

Genetic or a matter of lifestyle?

AS FAR back as 1959, medical researchers in Singapore already reported a higher incidence of coronary heart disease among Indians.

A study by University of Malaya professor C.S. Muir published in the British Heart Journal in 1960 reports that based on a study of 552 deaths in Singapore, Indians here were 10 times more likely to die of heart disease than the Chinese or Malays.

It also found that Indian Muslims who consumed more red meat, in particular mutton, were 20 times more likely to die of heart disease than the Chinese.

According to the latest Health Ministry statistics, among the 6,348 Singaporeans admitted to restructured hospitals after suffering heart attacks in 2007, Indians were staggeringly over-represented.

They formed almost 13 per cent of the total number of heart attack victims, despite making up only 7 per cent of the population.

Malays were also over-represented but to a lesser extent than Indians. They made up 17 per cent of the heart attack victims, despite comprising only 14 per cent of the population.

The Chinese made up 69 per cent of those who suffered a heart attack in 2007, despite comprising 74 per cent of the population.

To get a more accurate picture of the severity of the problem, Gleneagles Medical Centre cardiologist Mak Koon Hou tracked the trend over nine years.

His study, published in 2003, tracked data on Chinese, Malay and Indian Singaporeans aged 20 to 64 who suffered heart attacks from 1991 to 1999.

The conclusion: Indians were three times more likely to suffer a heart attack than the Chinese, while Malays were two times more likely.

Retired National University of Singapore (NUS) Associate Professor Kenneth Hughes, who has investigated the higher rate of heart disease among Indians since the early 1980s, says it is not just a local phenomenon.

Overseas research on South Asians - covering those of Indian descent born on the Indian subcontinent, including Sri Lanka, Bangladesh and Pakistan - found that they have at least twice, if not thrice, the rate of heart disease compared to other ethnic groups in their countries.

The World Health Organisation has predicted that by this year, India alone will account for 60 per cent of the world's cardiac patients, nearly four times its share of the world's population.
The Illinois-based CADI (Coronary Artery Disease among Asian Indians) research foundation headed by American-Indian doctor Enas A Enas also found that South Asians in the United States have three times the incidence of heart disease, compared to the general US population.
During the past 30 years, it noted that although the average age of first heart attacks increased by 10 years in the US, it decreased by 10 years in India.

And heart disease among Indians tends to be more severe, malignant and diffuse, meaning that, despite repeat surgery, artery blockages often return and cause death.

Dr Hughes, a Briton who retired three years ago and now lives in Singapore, says: 'It's an established fact that Indians are more likely to develop coronary heart disease. But the more interesting question is, Why is this so?

'Are Indians just born unlucky with the genes that predispose them to heart disease? Or is it diet and inactive lifestyle?'

Cardiologists such as Dr Dinesh Nair and his father, Dr V. P. Nair, both from Mount Elizabeth Hospital, and Dr Baldev Singh from Parkway East Hospital, who treat Indian patients from Singapore and around the world, say they have quite a few Indian patients in their 30s and early 40s.

A handful are even in their late 20s.

They all report that when heart disease strikes Indians, as well as occurring more often and earlier, it also tends to be more severe.

Says the older Dr Nair, who has been in practice for 35 years: 'My Indian patients have multiple blockages - five to six.'

The average Chinese patient typically has two or three blockages.

Part-roti prata

A 1996 study on 1,000 newborn babies in Singapore strongly suggested that Indians have the genetic dice loaded against them from the word go.

Analysing the cord blood of about 1,000 newborns, NUS Associate Professor Heng Chew Kiat and his team of six researchers found that Indian babies have about three times the level of cholesterol and lipoprotein (a) - a type of cholesterol - than Chinese babies.

Higher cholesterol, coupled with low levels of good cholesterol (HDL) and high levels of bad cholesterol (LDL) and lipoprotein (a), is associated with an increased risk of heart disease.
Still, Dr Heng, who is part of a team that developed a risk test for heart disease, says genetics accounts for only 20 per cent to 60 per cent of whether one gets heart disease.

'To put it another way, what you eat and your lifestyle account for 40 per cent to 80 per cent,' he explains.

The test developed by Dr Heng's NUS team examines 15 out of more than 200 genes that have been found linked to heart disease. It takes into account a person's lifestyle and environmental factors to calculate his or her overall risk of getting the disease.

Among the lifestyle factors looked at are smoking and exercise. Smoking, for example, is known to double or even triple the risk of heart disease, while lack of exercise increases the risk by about 20 per cent.

Says Dr Heng: 'As I tell my friends, any person's heart attack risk is part-genetic and part-roti prata and char kway teow.'

Dr Adrian Low of the National University Heart Centre, who studies how heart attacks happen, says dozens of genes have been found to contribute to a predisposition. Some are believed to affect arteries, others the processing of lipids in the blood.

'But of the several dozen genes, each may contribute just 1 per cent to a person's total risk, which is easily offset or compounded by lifestyle factors like diet and exercise.'

He says that studies have shown that traditional cardiovascular risk factors, such as high cholesterol and obesity, account for more than 90 per cent of the risk of heart attacks. And most of these risk factors are modifiable.

'Certainly, some of these risk factors may be contributed genetically but to date, no gene has been identified that has been convincingly shown to play a major role in determining heart attack risk,' he adds.

Coronary conundrum

ALTHOUGH there are no definitive answers yet from genetic science, research into heart disease risk factors among Indians has thrown up even more mysteries.

What adds to the puzzle for researchers is that despite their proclivity for heart disease, Indians tend to be less - rather than more - burdened with some traditional risk factors, such as smoking or hypertension, compared to other races.

In a study in the 1980s, Dr Hughes found that Indians did not have higher levels of hypertension than the Chinese or Malays. There were also fewer smokers among Indians.

Hypertension, or high blood pressure, forces the heart to work harder to pump enough blood and oxygen to the body's organs and tissues. Over time, the heart enlarges and weakens. Arteries also become scarred, hardened and less elastic.

These inconsistencies still hold true today.

A 2007 Health Ministry National Health Surveillance Survey to obtain information on the general health status and lifestyle practices of Singaporeans found that Malays and Chinese (12.5 per cent and 12.2 per cent, respectively) had a higher prevalence of reported hypertension, compared with Indians (9.3 per cent).

When it came to smoking, Malays had the highest daily smoking prevalence (23.2 per cent), followed by the Chinese (12.3 per cent) and Indians (11.4 per cent).

What about other risk factors, such as diabetes, a well-known precursor to developing heart disease?

The same survey found that more Indians (9.7 per cent) reported having diabetes, compared with 3.8 per cent of the Chinese and 6.2 per cent of Malays. This, Dr Hughes says, supports the belief that diabetes is the more significant risk factor for heart disease.

Being obese is another factor, but therein lies another puzzle.

Going by a common measure of obesity, called the body mass index, only 7.5 per cent of Indians were found to be obese, compared with 13.4 per cent of Malays and 4.3 per cent of Chinese, according to the same survey.

However, in this respect, Dr Hughes points out that how and where the fat is distributed on the body have a greater bearing.

He explains: 'Indian patients tend to be apple-shaped, with most of their fat concentrated round their waist, while the Chinese male is likely to have the fat distributed all over.'

In a mid-1990s study, he and a team at NUS measured the body mass index and waist-hip ratio of about 1,000 Chinese, Indians and Malays.

It concluded that Indians were more prone to 'central obesity', as well as insulin resistance and glucose intolerance, which is related to diabetes.

When a person eats, insulin is released to get glucose out of the blood and into the muscle cells that use it for energy. In insulin-resistant people, the pancreas responds by pouring out more insulin, resulting in a somewhat elevated blood level of glucose and a rise in triglycerides, which is linked to heart disease.

The same study also found that Indians had less good cholesterol (HDL) than Malays and Chinese. HDL is important as it removes cholesterol from clogged arteries.

Everyone is at risk

BESIDES the role of nature, however, nurture also plays a part, say doctors.

Here, diet is the chief culprit. Dr Singh notes that although many Indians tend to be vegetarian, their diet tends to be high in processed carbohydrates and cream.

'If a patient is insulin-resistant, the carbs will cause him to pile on fat,' he says.

Dr Hughes and his colleagues also found that Indians ingest significantly lower levels of vitamin C and selenium, a trace mineral. Studies have suggested that a link between lower levels of vitamin C and selenium increases the risk of heart disease.

'Lower vitamin C in Indians and Malays is probably because of its destruction by more prolonged cooking,' he says, referring to vegetable curries favoured by Indians.

What about lack of exercise, another contributory factor?

Ironically, the Health Ministry's 2007 survey found that of the one-quarter of respondents who said they exercised regularly - 20 minutes at least three times a week - Indians claimed they had the highest participation rate (36.9 per cent), followed by Malays (22.8 per cent) and Chinese (22.3 per cent).

This self-assessment may look impressive at first, but it seems most Indians simply do not exercise vigorously or long enough, even though they think they do.

Dr Singh says when it comes to staving off heart disease, one has to break a sweat for at least 30 minutes, five times a week - but many Indians often underestimate the frequency and intensity of the exercise needed.

Officials at Fitness Network gym, where Mr Maverick works out, report that only about 6 per cent of the members who work out at least three times a week are Indians. The rest tend to be Chinese or Caucasian.

Indeed, Mr Maverick agrees that he finds it difficult to convince his Indian friends to exercise with him.

'They say I am overdoing it, but I keep telling them that you need to exercise regularly and with intensity to benefit. A slow 10-minute walk to the bus stop won't do.'

Much less a saunter to the prata shop.

But even if Mr Maverick's exercise and diet regimen should fail him, he can take heart in a myriad of treatment options available today.

At the National Heart Centre Singapore in Outram, doctors saw 90,000 patients last year and performed 2,000 angioplasties and 700 bypass operations.

Thanks to computed tomography scanners, which produce startlingly clear pictures of a patient's heart and arterial blockages, they are able to make timely and accurate diagnosis.

Patients undergoing angioplasty, using a balloon at the end of a tube to open up blocked arteries and surgery to bypass the diseased arteries, all have good chances of survival.

Drugs called statins given early enough and in large-enough doses have also been shown to nip heart disease in the bud.

Cardiologists say, however, that they hesitate to prescribe statins freely. For one thing, they are expensive - a year's supply can cost between a few hundred dollars and $1,200.

'Statins are effective,' says Dr Singh. 'But I don't think the answer is a magic drug to prevent heart disease. The answer is to change your behaviour.

'Indian or not, there are ways you can fight heart disease: If you smoke, stop. If you are overweight, shed some pounds. Adopt a diet based on fruits, vegetables, whole grains, nuts and olive oil. Eat more fish. Exercise almost every day. Get enough sleep. And, most important of all, reduce stress.'

And Mr Maverick continues to work hard on all these fronts to defy the odds. 'I intend to live a healthy active life into my old age. I want to watch my kids grow up,' he vows as he puts on his running shoes.
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LIFESTYLE CHANGE

'Indian or not, there are ways you can fight heart disease: If you smoke, stop. If you are overweight, shed some pounds. Adopt a diet based on fruits, vegetables, whole grains, nuts and olive oil. Eat more fish. Exercise almost every day. Get enough sleep. And most important of all, reduce stress.'