LONDON (CBS Atlanta) – Firstborn children may have a higher risk of heart disease an diabetes in middle age than their younger brothers, says a new study featured on livescience.com.
New Zealand researchers studied 50 overweight men between the ages of 40 and 50. They compared the body mass index of firstborns with that of second-borns. They also looked at the men’s sensitivity to insulin, which is the hormone that regulates blood sugar levels.
The firstborn men were about the same height as their counterparts, but they weighed an average of 15 pounds more, says the study. Extra weight can lead to diseases of the heart. It also found that their insulin sensitivity was 33 percent lower than second-born men. When the body is not as sensitive to insulin, the pancreas creates more, which can lead to diabetes.
The researchers say they don’t know why the oldest male child would show these effects. Earlier research has shown that birth order can have an effect on the body’s metabolism.
The researchers say studies with larger groups are needed, with sibling pairs being ideal subjects.
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