A 10-year analysis of offspring patients in the Framingham Heart
Study suggests improvements in lipid profiles, particularly
beneficial changes in triglyceride and HDL-cholesterol levels [1].
During the most recent examination periods, HDL-cholesterol levels
rose and triglycerides decreased, despite an overall increase in body-
mass index (BMI), report investigators in the February 9, 2009 issue
of the Archives of Internal Medicine.

"If you ask any cardiologist what is the likelihood that a patient
with increasing body weight would also have their triglycerides go
down and their HDL-cholesterol levels go up, I would bet that almost
100% of them would tell you it's very unlikely this would happen,"
senior investigator Dr Sander Robins (Boston University, MA) told
heartwire. "Maybe you'd find one exercise nut or something like that.
The findings are counterintuitive, or counterscience, at least in
terms of the science we think we know."

The findings, which come as a surprise, also contrast with other
cross-sectional studies, including a recent National Health and
Nutrition Examination Survey (NHANES), which reported that plasma
levels of HDL and triglycerides were unchanged from 1988 to the most
recent examination period in 2002, despite increasing rates of
obesity in the US.

In this analysis, the researchers assessed lipid levels of 1666 men
and women participating in the three most recently completed
examinations of the Framingham Offspring Study. These examinations,
which took place between 1991 and 2001, were selected to correspond
roughly with the last two NHANES assessments. All individuals were
without cardiovascular disease and not currently prescribed lipid
and/or hormone-replacement therapy.

Over the three exams, total cholesterol levels were unchanged in men
and women, although BMI increased significantly. Despite the increase
in body mass, triglyceride levels declined and HDL-cholesterol levels
increased in both men and women. Consistent with these findings,
there was a significant decrease in the proportion of patients with
low HDL cholesterol and those with elevated triglyceride levels.

"Over this 10-year period, over three sequential exams, men and women
alike have had an increasing level of HDL cholesterol in concert with
a decreasing level of triglycerides," said Robins. "When you have
this reciprocal relationship between HDL and triglycerides, it is
much more apt to be a physiologically linked phenomenon than just two
separate measurements being affected independently. Our presumption
is that we're looking at something that's real, that's biologic,
because of this linked phenomenon."

Researchers say they have no certain explanation for these beneficial
changes in blood lipid levels in a "fairly large segment of the
Framingham Heart Study population," but Robins said one theory might
be based on changes in patterns of food consumption in the US. Recent
dietary surveys suggest increased consumption of carbohydrates and a
decrease in the consumption of fats, particularly saturated fats.
This would lead to more active and complete hydrolysis of
triglyceride-rich lipoproteins and would result in the increased
formation of HDL cholesterol.

"In this way, you do have the opportunity for invoking change in both
the triglycerides and HDL cholesterol in a reciprocal way," said
Robins. The dietary information available to the Framingham
investigators, however, is too crude to be able to detect changes in
the type of fat consumption, so further studies will be needed,
particularly in terms of having the results confirmed in other
studies, he added.


Ingelsson E, Massaro JM, Sutherland P, et al. Contemporary trends in
dyslipidemia in the Framingham Heart Study. Arch Intern Med 2009;
169:279-286. Abstract