Gene + Wrong Foods = Heart Disease
Meat Fats Worsen but Fish Oils Blunt Heart Disease Gene
Dec. 31, 2003 -- Six in 100 Americans carry gene variants that
greatly increase their risk of heart disease. But eating the right foods -- and
avoiding the wrong ones -- virtually eliminates this risk.
The heart-disease gene types -- variant forms of a normal gene
-- are more common among blacks, Asians, Pacific Islanders, and other racial or
ethnic groups than among Hispanics and non-Hispanic whites. But some people of
all races seem to carry the gene variants.
How bad are the gene variants? They pose a greater risk of
heart disease -- based on thickening of arteries -- than smoking, and nearly as
great a risk as diabetes. A diet high in arachidonic acid -- mostly found in
meat fats -- increases the bad effects of the inherited gene forms. But a diet
high in fish oils -- such as those found in salmon, tuna, and mackerel --
blunts these effects.
"These findings suggest that the [heart-protective] effects
of [oils] derived from fish might be more prominent in (or perhaps limited to)
persons with [the gene variants]," write Raffaele De Caterina, MD, PhD, and
Antonella Zampolli, PhD, of Italy's National Research Council. Their commentary
-- and the study itself -- appears in the Jan. 1, 2004, issue of The New
England Journal of Medicine.
The Origins of Heart Disease
The findings come from a groundbreaking study that pulls back
the covers shrouding the mysterious origins of heart disease. James H. Dwyer,
PhD, and colleagues at the University of Southern California and UCLA knew that
mice lacking the 5-lipoxygenase gene were nearly immune to atherosclerosis, or
hardening of the arteries.
To find out whether this gene was important in human disease,
they analyzed a racially diverse group of 470 healthy, middle-aged men and
women. They found that 6% of these people had a variant form of the gene.
Apparently, these gene variants increased a person's 5-lipoxygenase
That's bad, as it turns out. Theoretically, increased
5-lipoxygenase activity would cause cells of the immune system to accumulate
inside artery walls. As they accumulated, they cause inflammation and promote
the accumulation of cholesterol molecules in the artery wall. Over time, the
buildup of artery-clogging plaque leads to heart disease.
And that's what seems to happen. People with the gene variants
had much thicker artery walls than those with normal forms of the
5-lipoxygenase gene. Thicker artery walls is a marker for cardiovascular
Nutrition and Genetics Dance Together
But Dwyer's team didn't stop there. 5-lipoxygenase is an enzyme
that breaks down fats -- particularly arachidonic acid, which comes mainly from
fatty red meat -- into substances that cause inflammation. They reasoned that
the more arachidonic acid a person with the gene variant ate, the more signs of
heart disease they'd find.
And that, too, proved true. People with the gene variant were
particularly sensitive to the heart-clogging effects of a diet high in
But there was good news, too. People with the gene variant were
also particularly sensitive to the healthy effects of diets high in fish oils.
Those who ate the most of these oils were able to blunt the effects of their
genetic tendency toward heart disease.
"These findings could lead to new dietary and targeted
molecular approaches to the prevention and treatment of cardiovascular disease
according to genotype, particularly in populations of non-European
descent," Dwyer and colleagues suggest.