Diabetes, Heart, Stroke | December 11, 2014 | Author: The Super Pharmacist
Beta-glucan is a soluble fiber that is found primarily in oats. Beta-glucan is made up of long strings of glucose molecules arranged in a particular fashion that allows it to be soluble in water and act as a dietary fiber. Researchers have known for some time that oats are able to lower cholesterol, but only recently has this cholesterol-lowering effect been traced to beta-glucan. In fact, beta-glucan may also help people with diabetes, hypertension, and infections including HIV. We review the effects of beta-glucan on blood cholesterol levels and explore how it may be used in combination with statin medications.
Several studies have shown that beta-glucan derived from oats can lower total blood cholesterol and LDL cholesterol, also known as “bad” cholesterol.
For instance, a group of nearly 2000 men who have high blood cholesterol and were overweight participated in a randomised study in which one group consumed 35 to 50 g of oat bran per day while the other group did not eat oat bran. Both groups maintained a low-fat, low-calorie diet with similar exercise regimens.
Men in the oat bran group had substantial decreases in total cholesterol and LDL cholesterol, roughly 1.75 mmol/L total cholesterol and 1.45 mmol/L LDL cholesterol. Of note, the men who did not eat oat bran also had statistically less pronounced reductions in cholesterol levels.
A recent review of clinical trials examining the role of oat fiber and blood cholesterol supports the notion that beta-glucan can reduce cholesterol levels. Most trials find that people who consume a substantial amount of beta-glucan fiber in their diet can decrease total cholesterol levels by 5 to 15% and LDL cholesterol by 5 to 10%. The authors of this review article propose that people should consume at least 3 g per day of oat beta-glucan as part of a low saturated fat diet to obtain a clinically meaningful reduction in cholesterol levels. The effect seems to be most pronounced, however, in people who have high cholesterol levels.
Dietary fibers, including beta-glucan, are not absorbed across the gastrointestinal tract. In other words, almost all of the beta-glucan that is consumed in the diet passes through the body without being absorbed. Therefore, there are very few side effects associated with beta-glucan. However, despite a large number of clinical trials reporting the use of oat fiber and beta-glucans, few have discussed adverse events in their published reports.
This does not mean that beta-glucan is without side effects, it means that few researchers have quantified them during studies. It is safe to assume, though, that beta-glucan does not cause any serious adverse events since these would almost certainly be reported.
Since the fiber stays within the gastrointestinal tract, it is conceivable that beta-glucan may cause GI discomfort and bloating, just like any dietary fiber. Since additional content is held within the gastrointestinal tract, it draws water from the body into the intestines.
Likewise, dietary fiber affects metabolism of bacteria in the gut (i.e. fermentable). This may generate more gas. In general, these effects of dietary fiber can be avoided by slowly increasing the dose taken each day until reaching the optimum level. This allows the body, and particularly the gut, to adapt to the increased dietary fiber. And increase water intake.
Statin drugs such as atorvastatin and rosuvastatin are the principal cholesterol-reducing drugs used in medicine today. They have repeatedly been shown to reduce total and LDL cholesterol while increasing HDL or "good" cholesterol. No clinical studies have compared statins with beta-glucan directly to determine which can better lower blood cholesterol levels. However, mice were simultaneously fed soluble fiber and the Statin drug, atorvastatin. While it might be reasonable to assume that atorvastatin and beta-glucan would work together to reduce cholesterol levels, these researchers found that beta-glucan actually reduce the effect of atorvastatin in mice. They hypothesised that the oat fiber reduced the absorption of atorvastatin, thereby making it less effective. It is unclear what effect combining these substances would have in humans.
While statins are prescribed for virtually everyone with high blood cholesterol in Western countries, not everybody can take statins.
Some people develop serious muscle problems or liver problems because of statins. People with a neurological disorder known as myasthenia gravis usually cannot take statins drugs because it may aggravate muscle fatigue. Therefore, researchers tested the effect of beta-glucan in patients with myasthenia gravis who could not take statins. They found that consuming 3 g of beta-glucan each day for eight weeks significantly reduced total cholesterol and LDL cholesterol in people with myasthenia gravis.
The dietary fiber was safe and effective in this patient population.
It is important to note that while beta-glucan can be used as a substitute for statins drugs in specific patients, the degree to which cholesterol can be lowered is much higher in people who take statins drugs. For instance, beta-glucan appears to be most effective in people with moderate to high cholesterol levels. In these patients, beta-glucan may reduce total and LDL cholesterol by perhaps 5 to 6% on average. Atorvastatin, for comparison, can reduce LDL cholesterol by 40 to 60% and total cholesterol from 30 to 45%. Therefore, under ideal conditions for both substances, statins have a much more profound effect on cholesterol than beta-glucan.
Considering that beta-glucan may, at least in experiments done on mice, reduce the efficacy of statins, people who have been prescribed statins for high blood cholesterol should use beta-glucan with caution. On the other hand, for people who cannot take statins, beta-glucan may provide an option as part of a comprehensive cholesterol–lowering regimen that includes a low-fat diet and cardiovascular exercise.
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