2011年1月9日星期日

How To Lower Cholesterol: Which Supplements Work?


If you're looking for a natural way to lower your cholesterol -- in addition to watching what you eat and exercising -- there are plenty of dietary supplements on the market that claim to do the trick.

These claims aren't always backed up by research, however. Though not always perfect, scientific studies are the best way to determine if an alternative remedy really works. Below, we break down what the research does -- and doesn't -- say about the benefits of the most popular supplements for lowering cholesterol.


(The dried extract of the leaf of the artichoke plant,know as Cynara scolymus)

Very few quality studies on artichoke leaf extract and cholesterol exist, and the results have been mixed. In a rigorous 2000 study, people with total cholesterol in the high-risk range who took an artichoke supplement for six weeks lowered their low-density lipoprotein (LDL, or bad cholesterol) levels by 23 percent, on average. But a more recent trial of similar design found no measurable impact on either LDL or high-density lipoprotein (HDL, also known as good cholesterol).

The bottom line: More evidence is needed to confirm the effect of artichoke on cholesterol (or lack thereof). Don’t expect your LDL to plummet if you take artichoke supplements.


Several studies dating back to the 1990s have reported that, in high doses, various fenugreek seed preparations can lower total cholesterol and LDL, in some cases dramatically. (One study recorded a drop in LDL of 38 percent.) Almost without exception, however, the studies have been small and of poor quality.

The bottom line: Despite the studies frequently cited as proof of fenugreek’s ability to lower cholesterol, there is not enough evidence to support its use.


Each gram of soluble fiber that you add to your daily diet will lower your LDL by about two points, according to a 1999 review of the research conducted at the Harvard Medical School. The amount of fiber you’d need to eat to significantly lower your LDL is a bit unwieldy, however. Three bowls of oatmeal a day will only yield about three grams of soluble fiber, and fiber supplements can cause some gastrointestinal side effects.

The bottom line: A diet high in soluble fiber can lower your LDL. But the effect is likely to be relatively modest, and loading up on soluble fiber may be impractical.

In clinical trials using relatively high doses (three grams or more), fish oil has been shown to lower triglyceride levels -- the third component of your total cholesterol number -- by around 10 percent to 30 percent. (The higher your triglyceride levels, the more effective it is.) But fish oil doesn’t lower LDL; it actually tends to cause a slight rise in LDL.

The bottom line: Fish oil lowers triglycerides, which have been associated with an increased risk of heart disease. For most people lowering LDL is more 


In 2000, the federal Agency for Healthcare Research and Quality reported that garlic caused a small but measurable drop in both LDL and total cholesterol, but only in the short term (three months). Subsequent research hasn’t been as encouraging.

A 2007 study in the Archives of Internal Medicine found that taking raw garlic or garlic supplements over a six-month period did not cause a measurable effect on total cholesterol, LDL, HDL, or triglyceride levels.

The bottom line: Though garlic may help lower LDL temporarily, its ability to meaningfully affect cholesterol levels is questionable.


Several studies have found a beneficial effect from ginseng on one or more cholesterol components, but most of the studies were small, only a few were randomized, and none were blinded or placebo-controlled.

One study that found a drop in LDL levels of 45 percent and a rise in HDL of 44 percent wasn’t controlled, included only eight participants, and was funded by a Korean manufacturer of ginseng products.

The bottom line: Though the research can’t be ignored entirely, there isn’t enough to evidence to support the use of ginseng to lower cholesterol.


 
A tree-resin extract, long used in Ayurvedic medicine, that contains plant sterols (guggulsterones).
Early studies on guggul reported reductions in total cholesterol, LDL, and triglycerides of 10 percent or more, but most of the studies were small and flawed. Then, in 2003, a study in the Journal of the American Medical Association -- the first guggul study conducted in the U.S. -- found that guggul had no measurable effect on total cholesterol, HDL, or triglycerides, and that it caused an increase in LDL of about five percent.

The bottom line: The JAMA study was a black eye for guggul. More research is needed, but for now there is not enough evidence to justify using guggul to lower cholesterol.


A B vitamin (also known as nictotinic acid) that occurs naturally in meat, fish, and dairy. 
Clinical trials dating back to the 1970s have shown that niacin can lower LDL and triglycerides. But its most notable effect is on HDL, which it can raise by up to 35 percent. Niacin only has this effect at high doses of two grams to three grams a day, however, and is typically administered as a prescription drug (such as Niaspan).

Niacin is also available as an over-the-counter supplement in doses of 500 milligrams or more, but taking large amounts of niacin can cause potentially serious side effects.

The bottom line: Niacin boosts HDL, but niacin supplements should not be taken in lieu of a prescription.


A fungus that grows on rice and contains small amounts of lovastatin, a naturally occurring form of statin.
In numerous studies over the years, various red yeast rice preparations have been shown to lower LDL by around 20 percent to 30 percent, comparable to a prescription statin. In the most recent clinical trial, red yeast rice capsules lowered LDL by 21 percent.

The bottom line: Red yeast rice’s ability to lower cholesterol is proven, but its potency makes some experts wary. The amount of lovastatin in red yeast rice pills varies widely across brands (some may even be spiked with it), and due to safety concerns doctors discourage its use.


A protein found in soy foods such as tofu, edamame, and soy milk.
The FDA allows the labels of certain foods containing soy protein to claim that, as part of a heart-healthy diet, soy protein may help reduce the risk of heart disease by lowering LDL. Research has found that soy protein’s effect is relatively modest, however.

A 2006 review by the American Heart Association found that consuming 50 grams of soy protein a day -- twice as much as the FDA says is necessary to reduce the risk of heart disease -- results in an average drop in LDL of just three percent.

The bottom line: Soy protein does lower LDL, but only slightly. The size of the effect seems to have been overstated. (Still have questions about natural cholesterol-lowering remedies?


Extract from: huffingtonpost.com

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