While they can’t see everything, they can see how long they are likely to remain free of three common chronic diseases: diabetes type 2, cancer and cardiovascular disease, which includes stroke and heart issues.
These diseases are usually the result of many factors, so they reflect a wider sense of health and are closely linked to lifestyle choices.
The research, published in the British Medical Journal, showed that women who practised none of the five habits by 50 could reasonably expect to develop at least one of the diseases by the age of 73 years and eight months.
Fifty-year-old women who had maintained four or five of the habits could expect to live to 84 years and four months before succumbing to any of the illnesses.
For men, the age figures were a bit lower and the researchers couldn’t explain why. Fifty-year-old men who practised no healthy behaviours were likely to develop one of the conditions by 73 years and one month.
Those who maintained four or five habits could keep those diseases at bay at least until 81 and a half.
Even doctors don’t look after themselves
Frank Hu, the research’s senior author, says only 2 to 3 per cent of the health professionals in the study had maintained four of five healthy habits.
While these particular professionals may be expected to be more personally health aware and active, they seemed not to be.
“It may seem surprising, but the small percentages reflect the general population,” Professor Hu says.
“This study, however, provides strong evidence that lifestyle habits can increase the number of disease-free years in your life.”
As the number of extra disease-free years increased with each additional healthy habit, the results suggest that those who can’t manage all five should not feel discouraged from managing the ones they can.
Participants in the study were all over 30 when it began and although it is always best to adopt healthy habits early, the good news is that adopting them later will still produce benefits,
The 2.6 million Australians who currently smoke every day won’t be pleased to hear what a powerful determinant this habit has on their future health.
The worst habit for your health
Although all five habits were similarly significant, Hu stressed how important it could be to quit smoking.
“If you are a smoker, the single best thing you can do, is stop,” he says.
“Never smoked” was used as a health habit because even if you stopped some time ago, you still have some residual risk of heart disease or cancer.
Compared with those who had never smoked, men who quit more than a decade earlier, lost 1.9 disease-free years but those who quit more recently, lost 2.6.
“While you cannot change the past, if you stop smoking right away, the benefit will continue to accumulate over time,” says Hu, a professor of Nutrition and Epidemiology at Harvard’s TH Chan School of Public Health.
Assessing the impact of alcohol was more complicated. While there is evidence that a little alcohol can be beneficial in terms of cardiovascular disease, no amount of alcohol is regarded as safe in terms of cancer.
How bad is drinking? It’s complicated
There is a dose-relationship between cancer and alcohol.
As a healthy habit, the study recommended a moderate alcohol intake of up to one 175ml glass of wine a day for women and up to two for men.
But something interesting happened to teetotallers. Women who adhered to the other four habits but didn’t drink at all, lost almost one disease-free year. If they drank moderately, their prospects went up considerably.
This is what the numbers showed: On her 50th birthday, a woman who had maintained at least four out of five healthy habits could expect to gain an extra 10.6 disease-free years compared her peers who hadn’t adopted any of the habits.
But if this woman drank moderately while maintaining the other habits, she could expect 12.5 disease-free years – the highest possible target in the study.
Similarly, moderate drinking seemed good for men, taking them from 7.6 to 9.6 disease-free years.
While the longest disease-free life expectancy was among those who drank moderately, Hu says this went down in those who had more than two or three drinks a day.
“Never drinkers” had a life expectancy between moderate and heavy drinkers.
Within the study, the authors emphasised that current guidelines do not encourage non-alcohol drinkers to start just for the benefit of preventing cardiovascular disease.
Australia’s official position is that alcohol is never completely safe and that the more you drink, the greater the risk to your health.
To reduce the risk of disease or injury, healthy Australian adults are advised to drink no more than 10 standard drinks a week and no more than four on any one day.
Alcohol remains the most widely used drug in Australia with the greatest number of daily drinkers being 70 and older.
The problem of diet and exercise
On the question of a healthy body weight, the study’s findings would not hearten the 63 per cent of adult Australians who are overweight or obese.
The study regarded a body mass index (BMI) between 18.5 and 24.9 as optimal. It found obese adults with a BMI of 30 or more achieved the lowest proportion of disease-free life. So did men who smoked 15 or more cigarettes a day.
Regarding the exercise, almost half of Australian adults would be out of sync with the study’s recommendation of at least 30 minutes of moderate to vigorous activity daily, such as brisk walking.
Almost 60 per cent of Australian women are insufficiently physically active, as are 50 per cent of men.
Australians don’t do well in the diet stakes either. While the study regarded a diet high in plants and low in fats as optimum, more than a third of Australians’ energy intakes comes from junk food.
Overall, in the study population, 90 per cent of diabetes and 80 per cent of coronary heart disease, were attributable to not following a low-risk lifestyle.
So was 70 per cent of cardiovascular death and half of all cancer deaths.
But as this was an observational study, it could not conclude these lifestyle factors were directly responsible for extending a life free of disease. It did attempt to account for other factors, such as family medical history and ethnic background.
Hu says as most of the doctors and nurses in the study were white, the research team now wants to test the robustness of the results by seeing if they can be replicated in other populations.
For those who managed to stick to some of the good habits, there was a bonus. Not only did they reduce their risk of cancer, cardiovascular disease and diabetes, they improved their chances of survival in the event of being diagnosed with any of these diseases.