Brain regulates cholesterol in blood, study suggests

BBC News, By Emma WilkinsonHealth reporter, Sunday, 6 June 2010 17:12 UK

Too much cholesterol causes hardened fatty arteries, raising the risk of a heart attack.

The amount of cholesterol circulating in the bloodstream is partly regulated by the brain, a study in mice suggests.

It counters assumptions that levels are solely controlled by what we eat and by cholesterol production in the liver.

The US study in Nature Neuroscience found that a hunger hormone in the brain acts as the "remote control" for cholesterol travelling round the body.

Too much cholesterol causes hardened fatty arteries, raising the risk of a heart attack.

The research carried out by a US team at the University of Cincinnati found that increased levels of the hunger hormone ghrelin in mice caused the animals to develop higher levels of blood-circulating cholesterol.

Levels in the blood rise because signals from the brain prompt the liver to store less cholesterol, the researchers said.

It is known that ghrelin inhibits a receptor in the brain in its role in regulating food intake and energy use.

In a separate experiment, they found that blocking this receptor in mice also increased levels of cholesterol in the blood.

Potential treatment

The researchers said the finding needs to be replicated in humans but potentially opens up a new way of treating high cholesterol.

Study leader Professor Matthias Tschoep said: "We have long thought that cholesterol is exclusively regulated through dietary absorption or synthesis and secretion by the liver.

"Our study shows for the first time that cholesterol is also under direct 'remote control' by specific neurocircuitry in the central nervous system."

Fotini Rozakeas, cardiac nurse at British Heart Foundation, said: "This interesting study on mice shows for the first time that blood cholesterol levels can be directly controlled by signals transmitted from the brain to the liver where cholesterol is formed.

"This could potentially open up new forms of treatment to control cholesterol levels, which would be great news for people with heart and circulation problems."

She stressed that much more research would be needed before the mechanisms at play were fully understood.

"In the meantime, people should reduce the amount of saturated fat in their diet, take part in regular physical activity and, in some cases, take prescribed medicines such as statins, to keep their cholesterol levels under control."

'No fasting' for cholesterol test

BBC News

Patients may not need to fast before having their cholesterol tested, a major report has found.

After analysing data from 300,000 people, Cambridge researchers found results were just as accurate if the patient had eaten before the test.

It was thought the body needed time to remove fatty particles from the blood

For decades patients have been told to fast for 12 hours prior to a test.

It is hoped the study, published in the Journal of the American Medical Association, may inform new guidelines for doctors in the UK.

Cholesterol tests have long been a key part of assessing a patient's risk of cardiovascular problems, and those who turned up having eaten breakfast were required to make a fresh appointment.

It had been thought that the body needed enough time to digest food in the system and to clear any fatty particles from the blood in order to produce an accurate reading of so-called "bad" cholesterol - or low-density lipoprotein (LDL).

Financial pressure

But data from 68 long-term surveys in 21 countries suggests this is not the case.

"For decades, people have been asked to fast overnight before their cholesterol tests," lead researcher Professor John Danesh said.

"These findings indicate that cholesterol measurements are at least as good - and probably somewhat better - when made without fasting."

The study also adds to the ongoing controversy over whether testing for blood proteins called apolipoproteins is a more reliable way of predicting heart risk than cholesterol testing.

The studies showed that analysing "good" cholesterol - or high-density lipoprotein (HDL) in conjunction with LDL was just as informative as testing for apolipoproteins AI and B.

Professor Peter Weissberg, medical director of the British Heart Foundation, said: "Given the financial pressure the NHS is under, it's good news that doctors don't need to spend money on setting up more sophisticated tests based on apolipoproteins.

"But the study underlines the importance of all GPs being able to measure HDL cholesterol as well as total cholesterol, in order to make the best predictions about heart disease risk."

Not all doctors currently use tests which differentiate between the two different forms of cholesterol.

Societies involved with heart care are currently drawing up new guidelines for health professionals in the UK, where cardiovascular disease - CVD - is the leading form of death.

Gene Mutation Is Tied to Fast Fat Breakdown

The New York Times, By GINA KOLATA, December 11, 2008

 

For the sake of heart disease research, 809 members of the Old Order Amish community agreed to go to a clinic in Lancaster, Pa., near their homes, and drink a rich milkshake that was made mostly of heavy cream. Over the next six hours, a group of investigators took samples of their blood, determining how much fat was churning through their bloodstreams.

 

Most of the study participants responded as expected — their levels of triglycerides, a common form of fat in the blood, rose steadily for three to four hours and then declined. But about 5 percent had an extraordinary reaction: their triglyceride levels started out low and hardly budged.

 

It turns out, the researchers report in the Friday issue of the journal Science, that those individuals who barely responded have a mutation that disables one of their two copies of a gene called apoC-III. The gene codes for a protein, APOC3, that normally slows the breakdown of triglycerides.

 

With the mutated gene, people break down triglycerides unusually quickly. And, the investigators find, they also have low levels of LDL cholesterol, which at high levels increases heart disease risk. They have high levels of HDL cholesterol, which is associated with a decreased risk of heart disease. And they appear to have arteries relatively clear of plaque.

 

To find the gene mutation, the researchers, led by Toni I. Pollin, an assistant professor of medicine at the University of Maryland School of Medicine, scanned the entire genomes of their study subjects, looking for genetic regions that were linked to levels of blood triglycerides. That led them to a region containing the apoC-III gene. When they sequenced it, they found the mutation that destroyed its function.

 

Dr. Alan R. Shuldiner, head of the division of endocrinology, diabetes and nutrition at the University of Maryland School of Medicine in Baltimore and the senior author of the paper, said that the Amish were ideal for the study because they were an isolated population that had been in this country for 14 generations and whose members shared many genes.

 

In this case, Dr. Pollin said, she and her colleagues traced the apoC-III mutation to a member of the Amish community who was born in the 18th century.

 

The gene is also regulated by insulin, noted Dr. Daniel J. Rader, a heart disease researcher at the University of Pennsylvania, and people with diabetes have high levels of APOC3, high levels of triglycerides and an increased risk of heart disease.

 

The discovery of the gene mutation, researchers say, helps bolster the case that triglycerides are related to risk of heart disease and that APOC3 is an important contributor. But clinical applications may be years away.

 

Dr. Ira J. Goldberg, chief of the division of preventive medicine and nutrition at Columbia, said the triglyceride case had mostly rested on studies showing an association between high triglyceride levels and an increased incidence of heart disease. But that, Dr. Goldberg added, is not cause and effect. The new study provides more direct evidence.

 

“Here we have a group of people with a genetic mutation that lowers triglycerides,” Dr. Goldberg said. “They seem to have less cardiovascular disease.”

 

As for apoC-III, the study clarifies its role, said Dr. Alan R. Tall, head of the molecular medicine division at Columbia. “It was known from animal studies that apoC-III might have a role like this,” Dr. Tall said. “But the human information is really novel. We suspected it might be the case but this nails it down.”

 

Dr. Rader agreed. “This is among the strongest human evidence we have that APOC3 is quote, unquote, bad,” he said. “If you had a drug to turn off the gene to prevent as much APOC3 being made, this study suggests that that would be beneficial to do.” But he added that there were no such drugs on the immediate horizon.

Plant sterols and stanols: another natural way to lower cholesterol

Jill K. Fulk, R.D., L.D. , MedCentral.org

Registered and Licensed Dietitian

A diet high in fiber and low in dietary cholesterol and saturated fats is a great start for lowering blood cholesterol. For people who have high cholesterol, a heart-healthy diet may also include daily doses of plant sterols and stanols.

Plant sterols and stanols are natural edible substances that have shown to lower LDL (bad cholesterol) without affecting HDL (good cholesterol) or triglycerides. Research has shown that incorporating these into the diet can lower LDL by 10 percent to 15 percent. This is good because LDL cholesterol may be the most dangerous. It contributes to hardening and clogging of the arteries, leading to heart attack and stroke.

Plant sterols and stanols are structurally similar to cholesterol and compete for absorption, thus interfering with the body's ability to absorb cholesterol. Plant sterols are naturally found in a variety of fruits, vegetables, oils, nuts, seeds, cereals and legumes (dried beans, peas and lentils). Plant stanols are found in vegetable oils, beans and corn.

In 2000, the Food and Drug Administration authorized a labeling claim that "diets low in saturated fat and cholesterol that include at least 1.3 grams of plant sterol esters or 3.4 grams of plant stanol esters, consumed in two meals with other foods, may reduce the risk of heart disease." Unfortunately, the average intake of plant sterols and stanols is only 250 milligrams and 25 milligrams per day, respectively, because they occur in food in very small amounts. Therefore, margarine spreads have been fortified with them and new sterol/stanol containing products are being introduced into the market, which will make it easier to achieve recommended amounts.

Take Control and Benecol are both available in regular and "light" forms. They should be used in place of regular butter or margarine, and the lower fat varieties should not be used for baking, cooking or frying. Studies have shown that when consumed with a heart-healthy diet, Take Control can lower LDL levels by up to 17 percent when used twice daily to provide 3.4 grams of plant sterols. Consuming three servings of Benecol a day for a total of 5.1 grams of plant stanols, can lower LDL by up to 14 percent and total cholesterol up to 10 percent.

Also available are supplements such as Benecol SoftGels (Benecol), Cholest-Off (Nature Made) and Cholesterol Success Plus (Twinlab). Most recommend two capsules twice a day. These are more expensive; however, some people may prefer to take capsules instead of using margarine. You can also drink Minute Maid Premium Heart Wise (Coca-Cola Co.) orange juice and get 1 gram of plant sterols in an 8-ounce serving.

If you decide to incorporate plant sterols and stanols in to your diet, make sure you discuss this with your health care provider first. For more information, visit www.takecontrol.com, www.Benecol.com, www.nhlbi.nih.gov or www.americanheart.org.

Related Article : Unilever Unveils Promise Activ(TM) SuperShots(TM), the First Mini Drink With Cholesterol-Lowering Natural Plant Sterols

Living Alone Doubles The Risk Of Serious Heart Disease

Living Alone Doubles The Risk Of Serious Heart Disease

MedicineWorld.Org

People who live alone double their risk of serious heart disease as those who live with a partner, suggests research in the Journal of Epidemiology and Community Health. This includes severe angina and heart attack.

The finding is based on a study of more than 138,000 adults between the ages of 30 and 69 living in one area (Aarhus) of Denmark.

Between 2000 and 2002, 646 people were diagnosed with severe angina, or sustained a heart attack, or sudden cardiac death, a spectrum of conditions known as acute coronary syndrome.

When analysed in detail, using information from population registers, poor educational attainment and living on a pension were linked to an increased risk of the syndrome.

But the two strongest predictive factors for the syndrome were age and living alone.

Women above the age of 60 and living by themselves, and men over the age of 50, in the same position, were twice as likely to have the syndrome as everyone else.

Lone women over 60 comprised just over 5 per cent, and lone men over 50 just under 8 per cent, of the whole population.

Yet lone women in this age group accounted for a third of all deaths from the syndrome within 30 days of diagnosis, while lone men in this age group accounted for two thirds of deaths.

The lowest risks included cohabiting with a partner, a high level of education, and being in work. Women divorcees also enjoyed a lower risk of the syndrome.

The authors say that certain risk factors tend to be more common in the lifestyles of those who live by themselves, which may help to explain the differences.

These include smoking, obesity, high cholesterol and fewer visits to the family doctor. People living on their own may be less able to draw on social support networks as well, say the authors.