Rising diabetes, obesity rates putting ethnic groups' heart health at risk

TORONTO -- Steadily rising rates of obesity, diabetes and high blood pressure over the last decade have dramatically increased the risk of heart attacks and strokes among some groups of ethnic Canadians, researchers say.

An Ontario study determined that from 2001 to 2012, diabetes rates more than doubled among South Asian men and almost doubled among black women.

While obesity levels rose among all ethnic groups and sexes, the biggest increase was observed in Chinese men, whose rate more than doubled during the study period.

"We found that the most striking difference was among the prevalence of diabetes," said lead researcher Dr. Maria Chiu, a scientist at the Institute for Clinical Evaluative Sciences (ICES) in Toronto.

"It was most stark among South Asian men. The prevalence of diabetes doubled over the 12-year period we looked at, from seven per cent to 15 per cent, and among black women it also increased, from about six per cent to 12 per cent."

The study, published Monday in the journal BMJ Open, analyzed data from almost 220,000 Ontario residents who responded to Statistics Canada's Canadian Community Health Surveys from 2001 to 2012.

It is believed to be the first in Canada to examine ethnic-specific cardiovascular risk-factor trends over time.

"We know that people who come to Canada are generally healthier to begin with -- this is (called) the healthy immigrant effect -- and then the longer they stay here, they pick up the bad habits of the Western culture," said Chiu.

"For example, they eat more fatty foods, they eat more meat, more processed foods, as well as eat between meals."

The analysis showed that black women and men and South Asian men had the greatest increases in risk factors for declining cardiovascular health over the period.

Poor diet was a strong indicator behind the elevation in the risk for heart attack and stroke, said Chiu.

According to the Statistics Canada health surveys, the proportion of South Asian men who reported that they didn't eat fruits or vegetables at least three times a day increased significantly over the past 12 years.

"So this is suggesting that their diet might be becoming progressively worse," she said.

Black females had a higher risk of developing cardiovascular disease than black males, primarily because of poorer diet and higher levels of psychosocial stress.

This group of women had the most "drastic" increase in rates of high blood pressure among the ethnic communities studied, jumping from 20 per cent in 2001 to 27 per cent in 2012.

"That's a 30 per cent increase in a little over 10 years," said Chiu.

Black women were more likely to be obese and less likely to consume fruits and vegetables regularly, she said, noting that 20 per cent of black females were obese in 2012, compared to 16 per cent of black males, although the latter's obesity rate also went up over time.

Obesity can lead to Type 2 diabetes, which raises the risk of heart attack, stroke and other serious heath conditions like kidney failure.

However, the jump in obesity rates was most pronounced among Chinese men, the ICES scientists discovered.

"This is concerning because previous research ... has found that Asians are particularly sensitive to weight gain, meaning that their risks of diabetes and cardiovascular disease are elevated much more than the white population with small increases in weight," said Chiu.

Canada is among the most ethnically diverse countries in the world. In 2011, more than six million foreign-born individuals were living in Canada, representing one-fifth of the population.

If nothing is done to reverse the trends shown by the study, the health of such vulnerable ethnic groups will continue to worsen, she predicted.

"And therefore, we need both population-based strategies to combat obesity as well as ethnically tailored strategies."

Dr. Sonia Anand, a researcher in population cardiovascular health at McMaster University in Hamilton, said the ICES findings are valuable because they show how risk factors can change over time.

"We all are aware that certain non-white ethnic groups are at increased risk of diabetes and obesity, and this work is important really for the next step, which is how to address the issue of prevention," said Anand, who was not involved in the study.

Part of that is tailoring treatment of the risk factors for heart disease and stroke to individuals within particular ethnic groups, she agreed.

"But even more importantly would be community intervention strategies, where we try to affect influences on health behaviours in the broader environment in order to reduce adverse health behaviours."

Those strategies include making communities more walkable to encourage physical activity, increasing the availability of healthy foods and continuing to beef up policies that discourage smoking.