Pharmaceutical companies are racing to develop a new class of drugs that may lower blood levels of LDL cholesterol to a point few scientists had believed attainable, The New York Times reported last week. For many people with high cholesterol, the breakthrough can’t come soon enough.

Statins, the miracle drugs responsible for keeping cholesterol in check in wide swaths of the population, may be reaching the limits of their effectiveness. Average cholesterol levels in Americans have stopped falling since 2008, according to a large analysis of patient records published recently in PLoS One.

Researchers at Quest Diagnostics, a national laboratory chain, reviewed blood levels of LDL, the so-called bad cholesterol, in 105 million adults tested by the company between 2001 and 2011. Average LDL levels declined from 120 milligrams per deciliter of blood in 2001 to 104.7 in 2008, about a 13 percent drop.

But in the next three years, average LDL levels flattened out.

An LDL of 100 mg/dL is considered healthy, but experts say people at very high risk of heart disease should bring their levels down even further, to about 70 mg/dL or lower. The percentage of patients with an LDL under 100 mg/dL rose from 26 percent in 2001 to 45.6 percent in 2008, then leveled off. Those with a high LDL of 160 mg/dL or more dropped from 13.7 percent in 2001 to 6 percent in 2011.

The study was not a random sampling; it comprised individuals whose physicians had requested cholesterol tests. Still, the findings have worried experts.

“The study suggests that the progress has slowed in systematically lowering cholesterol levels,” said Dr. Steven Nissen, the chairman of cardiovascular medicine at the Cleveland Clinic, who was not involved in the study.

The authors suggested that these results may affect cardiovascular mortality rates as well. “There has been approximately a 70 percent decrease in cardiovascular disease mortality from 1970 through 2009,” said Dr. Harvey W. Kaufman, senior medical director at Quest Diagnostics and an author of the study. “A large portion of this was driven by the reduction in cholesterol, and this progress is now threatened.”

A combination of factors have brought down LDL levels, including improved diet and exercise. But statins have been a significant driver over the past 25 years.

The study did not look at causes for the plateau, but Dr. Kaufman and his colleagues speculated that the recession may have played a role by influencing patients’ ability to see their physicians and fill their prescriptions for statins. Tough times also may have affected lifestyle factors that can contribute to higher LDL, including stress levels, a high-fat diet and lack of exercise.

The number of prescriptions for statins rose dramatically almost every year since 2001, but the growth slowed in 2010, according to IMS Health, a health care information company. There also was a decline in physician office visits, which means that fewer people are getting their cholesterol tested and treated.

But other experts suggested that LDL levels have flattened out simply because they may be as low as they can go with the available treatments. “We could conceivably be experiencing a bottoming out of the statin effect,” said Dr. Ronald M. Krauss, director of atherosclerosis research at Children’s Hospital Oakland Research Institute in Oakland, Calif.

According to Dr. Elsa-Grace V. Giardina, director of preventive cardiology training at Columbia University Medical Center, “There may be a rapid rate of change at first, and then you get to a threshold point for which you can’t do much more.”

To bring LDL levels lower, physicians may need to increase statin doses, particularly in those who are at high risk of heart disease. “The official recommendation has been to reduce LDL as much as possible, but physicians don’t always adjust statin dose in practice,” Dr. Krauss said. “If it starts off high and it comes down to 100, doctors may be satisfied with that.”

But doctors may also have been reluctant to raise doses because of the risk of serious side effects like muscle pain, weakness and increased blood sugar levels.

The trend is to focus on “therapeutic lifestyle modification, for individuals to have a greater input into their health, rather than just popping a pill,” Dr. Giardina said.

Obesity may also be limiting the effectiveness of statins. “You have to wonder how much obesity is contributing to this plateau,” Dr. Giardina said. Obesity raises the risks of high cholesterol, high blood pressure, high triglycerides and diabetes, all risk factors for heart disease.

She believes average cholesterol levels may be higher than the study found: “Excluded in this analysis are disadvantaged people who don’t have health care and among whom obesity is a major problem.”

Even if new drugs are found, the obesity epidemic may blunt their effects.

“We’re now to the point that a very large fraction of the adult population is obese,” Dr. Nissen said. “We will not make any further progress as a society unless we find a way to deal with the obesity epidemic.”

Connie’s Comments: Cheap processed foods and fast foods available to the masses are maybe the culprit of the obesity epidemic. Let’s go to the farmer’s market, plant more veggies in our gardens and eat an apple and banana a day. It only takes a minute to microwave an egg in a mug of water (no shells) and presto you have one boiled egg (cheap and complete protein, no more snacking on empty calories, add a spinach or swiss chard as your carbs). Let the egg be hormone free.

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