Cholesterol Research: Two New Studies Emphasize Importance of Lowering LDL

VRP Staff

Lowering levels of the “bad” LDL cholesterol early in life can protect against coronary heart disease while consuming beta-glucan can help lower LDL levels, two new, separate studies have found.

In the first study, published in The New England Journal of Medicine, researchers found that subjects who had lower low-density lipoprotein (LDL) cholesterol in their blood from birth, due to a genetic variation, were significantly less likely to develop coronary heart disease later in life compared to subjects who did not have this genetic variation.

Researchers examined data from more than 12,000 subjects ages 45 to 64 who participated in the Atherosclerosis Risk in Communities Study (ARIC), which tracked the health of participants from four communities in Mississippi, Minnesota, North Carolina and Maryland for 15 years. They determined that subjects whose genetic variations in a gene called PCSK9 caused their LDL levels to be about 40 mm/dL below average were eight times less likely to develop coronary heart disease than those without the mutations. Subjects with genetic variations that produced a 20 mg/dL reduction in LDL compared to average were two times less likely to develop heart disease.

Of the 3,363 black subjects examined, the 2.6 percent with mutations in PCSK9 had a 28 percent reduction in mean LDL cholesterol and an 88 percent reduction in the risk of coronary heart disease. Of the 9,524 white subjects examined, 3.2 percent had a sequence variation in PCSK9 that was associated with a 15 percent reduction in LDL cholesterol and a 47 percent reduction in the risk of coronary heart disease.

The PCSK9 gene is involved in cholesterol production by virtue of its ability to produce an enzyme that reduces the quantity of LDL receptors on the liver’s surface. The LDL receptors are responsible for removing LDL from the blood. Genetic mutations inactivate PCSK9, causing lower levels of the PCSK9 enzyme, which in turn leads to higher levels of LDL receptors. This in turn increases the amount of LDL cholesterol the liver cells can remove from the blood, causing a reduction in LDL levels in the blood of people with the mutations. Ironically, statin drugs, although they can lower cholesterol, may increase the production of the PCSK9 enzyme.

Previous research has established a link between high levels of LDL cholesterol and the development of coronary heart disease. The findings in this current study further confirm that lowering LDL cholesterol even early in life can help prevent cardiovascular disease.

According to the study authors, “These data indicate that moderate lifelong reduction in the plasma level of LDL cholesterol is associated with a substantial reduction in the incidence of coronary events, even in populations with a high prevalence of non-lipid-related cardiovascular risk factors. “

Another study published at the same time in the American Journal of Clinical Nutrition showed that beta-glucan can lower LDL cholesterol levels in human subjects.

Researchers examined the effects of a beta-glucan–enriched fruit juice on serum lipids and lipoproteins and on markers of cholesterol absorption and synthesis. In addition, they measured effects on lipid-soluble antioxidants.

Healthy subjects were divided into two groups. The 22 subjects in the placebo group consumed a fruit drink providing 5 grams rice starch per day. The 25 subjects in the treatment group received a fruit drink with beta-glucan from oats for five weeks.

The researchers determined that compared to control subjects, subjects consuming beta-glucan experienced a significant reduction in serum concentrations of LDL and total cholesterol. No significant effects were found on fat-soluble antioxidants.

According to the study authors, “A reduced cholesterol absorption contributes to the cholesterol-lowering effect of beta-glucan without affecting plasma concentrations of lipid-soluble antioxidants. “

References:
Cohen JC, Boerwinkle E, Mosley TH Jr, Hobbs HH. Sequence variations in PCSK9, low LDL, and protection against coronary heart disease. N Engl J Med. 2006 Mar 23;354(12):1264-72.

Naumann E, van Rees AB, Φnning G, Φste R, Wydra M, Mensink RP. ί-Glucan incorporated into a fruit drink effectively lowers serum LDL-cholesterol concentrations. American Journal of Clinical Nutrition. 2006 March; 83(3):601-605.