Healthy Lifestyle or Genetics?

Two large studies confirm a healthy lifestyle has the biggest impact on cardiovascular health. One study shows the majority of people who adopted healthy lifestyle behaviors in young adulthood maintained a low cardiovascular risk profile in middle age. The other study shows cardiovascular health is due primarily to lifestyle factors and healthy behavior, not heredity. The studies will be presented at the American Heart Association Scientific Sessions 2010.

"Health behaviors can trump a lot of your genetics," said Donald Lloyd-Jones, M.D., chair and professor of preventive medicine at Northwestern University Feinberg School of Medicine and a staff cardiologist at Northwestern Memorial Hospital. "This research shows people have control over their heart health. The earlier they start making healthy choices, the more likely they are to maintain a low-risk profile for heart disease."

The first Northwestern Medicine study investigated why most young adults, who have a low-risk profile for heart disease, often tip into the high-risk category by middle age with high blood pressure, high cholesterol and excess weight. The unhealthy shift is the result of lifestyle, the study found. More than half of the young adults who followed five healthy lifestyle factors for 20 years were able to maintain their low-risk profile for heart disease though middle age.

Researchers tracked participants' diet, physical activity, alcohol consumption, smoking, weight, blood pressure and glucose levels at the baseline year, year seven and year 20. After 20 years, the prevalence of a low-risk profile was 60 percent for participants who followed all five healthy lifestyle factors, 37 percent for four factors, 30 percent for three factors, 17 percent for two and 6 percent for one or zero. The results were similar for men only, women only, black only and white only.

The second Northwestern Medicine study examined three generations of families from the Framingham Heart Study to determine the heritability of cardiovascular health. Heritability includes a combination of genetic factors and the effects of a shared environment such as the types of foods that are served in a family. Only a small percentage of the United States population -- 8 percent -- has ideal levels of all the risk factors for cardiovascular health at middle age. The study found that only a small proportion of cardiovascular health is passed from parent to child; instead, it appears that the majority of cardiovascular health is due to lifestyle and healthy behaviors. "What you do and how you live is going to have a larger impact on whether you are in ideal cardiovascular health than your genes or how you were raised," said Norrina Allen, the lead study author and a postdoctoral fellow in preventive medicine at the Feinberg School. The Northwestern Medicine study looked at three generations of families including 7,535 people at age 40 and a separate group of 8,920 people at age 50. The goal was to see who was in ideal cardiovascular health at these two critical periods in middle age.

Piggybacking on the aforementioned studies, regular exercise can reduce around two dozen physical and mental health conditions and slow down how quickly the body ages. Health conditions covered by the review include: cancer, heart disease, dementia, stroke, type 2 diabetes, depression, obesity and high blood pressure.

Published in the December issue of IJCP, the International Journal of Clinical Practice, the study says that apart from not smoking, being physically active is the most powerful lifestyle choice any individual can make to improve their health. Health benefits identified by the review include:

• Regular moderate to intense physical activity is associated with decreased risk of coronary heart disease and ischaemic and haemorrhagic stroke.
• A growing body of evidence suggests that increasing physical activity can also reduce the risk of certain types of cancers, osteoporosis, type 2 diabetes, depression, obesity and high blood pressure.
• Evidence of the beneficial effects of physical activity in the primary prevention and management of cancer is growing and there is an association between higher levels of physical activity and lower cancer death rates.
• Research has found that walking or cycling for at least an half-an-hour a day is associated with a reduction in cancer and that when this is increased to an hour cancer incidence falls by 16 per cent.
• Evidence is mixed when it comes to specific cancers. Research has shown a strong relationship between increased physical activity and reduced colon cancer in both sexes. And men who are more active at work -- not just sitting at a desk -- have lower rates of prostate cancer.
• Other cancer studies show that physical activity after diagnosis can aid recovery and improve outcomes.
• Studies have also shown that men who are physically active are less likely to experience erection problems.
• There is growing evidence that physical activity could decrease the risk of dementia in the elderly.
  

Recommendations identified by the review include:

• Healthy adults aged between 18 and 65 should aim for 150 minutes of moderate intensity physical activity a week, such as 30 minutes of brisk walking, five days a week. And people who undertake more vigorous intensity exercise, such as jogging, should aim for 20 minutes three days a week.
• Healthy adults should aim for two strength-training sessions a week that work with the body's major muscle groups.
• Older people can benefit from exercise that helps to maintain their balance and flexibility.
• People who are physically active should continue to exercise even when they become middle aged or elderly and those who aren't should increase their physical activity.Not smoking and following a healthy diet is also important.
  
• Ideally, to gain maximum health benefits people should exercise, not smoke, eat a healthy diet and have a body mass index of less than 25.