When Diet Doesn't Lower Cholesterol
There May Now Be a Way To Find Out Why With a Simple Blood Test
July 7, 2003 -- New research may help explain why some people can't seem to lower their cholesterol even though they're eating a low-fat, low-cholesterol diet.
People with high levels of C-reactive protein (CRP) in their blood - which may indicate inflammation and is associated with an increased risk of heart disease -- did not see as much of a heart-healthy benefit from a low-fat, low-cholesterol diet. While the findings must be confirmed in larger studies, researchers from John's Hopkins Medical Institutions suggest that a one-diet-fits-all approach to reducing cardiovascular risk may be too simplistic.
"The idea that everyone should be eating the exact same diet to lower their risk of heart disease may not be exactly right," Johns Hopkins researcher Thomas P. Erlinger, MD, tells WebMD. "It may be that in the future we can tailor a diet to an individual's personal profile, but we just aren't there yet."
Erlinger and his colleagues used a blood test to measure the amount of CRP in 100 people participating in the larger, ongoing Dietary Approaches to Stop Hypertension (DASH) trial. For three months participants ate either the DASH diet, which included lots of fruits and vegetables and restricted calories from fat to 27% per day, or a comparison diet, in which 37% of daily calories came from fat.
Study participants whose CRP levels were originally below average saw dramatic reductions in cholesterol after 12 weeks on the DASH diet. Total cholesterol dropped by almost 9% and LDL, or bad cholesterol, dropped by almost 12%. In participants with higher than average CRP levels, total and LDL cholesterol levels dropped by just 3% each. The findings are published in the July 15 issue of Circulation.
The American Heart Association (AHA) currently recommends CRP testing only for people who are at increased risk of heart disease but have no clear treatment course. Knowing a patient's level of inflammation can help doctors determine if they need aggressive treatment.
Erlinger says it is too soon to know if his findings have clinical significance, and AHA nutrition expert Ronald M. Krauss, MD, agrees.
"The main message here ought to be, 'stay tuned,'" Krauss tells WebMD. "This is the first study to suggest that inflammation impacts the response to a traditional cholesterol lowering diet. We have to be careful in how this is relayed to the public."
But Krauss adds that it is becoming more and more obvious that there is a tremendous variability in responses to restricted diets designed to lower body weight, blood pressure and cholesterol. Several recent studies have shown that people who lost weight on high-protein, relatively high-fat diets lowered their cholesterol, suggesting that weight loss alone, no matter how it is achieved, plays a significant role in lowering cholesterol.
"There is a tremendous amount of variation in individual response to diets that we recommend for reducing heart disease risk," he says. "Identifying the reasons for this will allow us to better identify patients who can benefit from aggressive treatment with medications like statins."