Doctors have long warned about the health hazards of high cholesterol but a growing body of evidence indicates that very low cholesterol can be dangerous too. Low cholesterol levels have been associated with depression, anxiety, violent behavior, suicide and hemorrhagic stroke.
Treatment & Prevention
Fat absorption requires the presence of bile as an emulsifier. Both a very low fat diet and poor bile flow can work to keep cholesterol levels lower than they should be. Thinning the bile can help raise low cholesterol levels.
Complications
A study of 121 healthy young women found that those with low cholesterol levels - below 160mg/dl - were more likely to score high on measures of depression and anxiety than women with normal or high cholesterol levels. Normal cholesterol levels are considered to fall within the range of 180mg/dl to 200mg/dl. There is now a compelling body of evidence in both men and women that low cholesterol is a potential predictor for depression and anxiety in certain individuals. [Psychosomatic Medicine, May 1999]
Data from more than 300 peer-reviewed medical reports showed that men with blood cholesterol levels below 160mg/dl tended to be the victims of homicide, suicide or fatal accidents 50-80% more often than those with the highest levels of cholesterol. The statistics for women showed a similar increase of 30%. The author of the review said that there may be a possible link between low cholesterol and a reduction in the brain chemical serotonin. Individuals with low serotonin levels are known to be more likely to commit suicide, especially by violent means, as well as homicide.
Okay, greeaaattt, anything else?
http://www.medscape.com/viewarticle/563575Low Maternal Total Cholesterol Linked to Preterm Delivery
October 1, 2007 — Mothers with low cholesterol (<10th>Pediatrics.
"Based on our initial findings, it appears that too little cholesterol may be as bad as too much cholesterol during pregnancy, but it is too early to extrapolate these results to the general population," senior author Max Muenke, MD, from the National Human Genome Research Institute (NHGRI) of the National Institutes of Health in Bethesda, Maryland, and colleagues. "More research is needed to replicate this outcome and to extend it to other groups. For now, the best advice for pregnant women is to follow the guidance of their health care providers when it comes to diet and exercise."
The investigators retrospectively evaluated mother–infant pairs from a cohort of 9938 women referred to South Carolina prenatal clinics for routine second-trimester serum screening. Low total cholesterol was defined as lower than the 10th percentile of assayed values in banked sera (159 mg/dL at mean gestational age of 17.6 weeks).
"The right amount of cholesterol is fundamental for good health, both before and after birth," Dr. Muenke said. "During pregnancy, cholesterol is critical for both the placenta and the developing baby, including the brain."
Inclusion criteria were age 21 to 34 years, nonsmoking, and without diabetes in the women, with a liveborn neonate after a singleton gestation. Before risk group assignment, total cholesterol (TC) values of eligible mothers were adjusted for gestational age at screening.
Of 1058 women studied, 118 women had low total cholesterol and 940 women had higher total cholesterol. Multivariate regression models compared rates of preterm delivery, fetal growth parameters, and congenital anomalies between women with low total cholesterol and those with mid–total cholesterol values (<10th>90th percentile).
In mothers with low total cholesterol, prevalence of preterm delivery was 12.7% vs 5.0% in mothers with mid–total cholesterol. Low maternal serum cholesterol was associated with preterm birth only among white mothers. On average, term infants of mothers with low total cholesterol weighed 150 g less than did those born to control mothers. Although low maternal serum cholesterol was not associated with risk for congenital anomalies, there was a statistically insignificant trend of increased risk for microcephaly among neonates of mothers with low total cholesterol.
As in earlier studies, very high cholesterol levels (>261 mg/dL) were a major risk factor for premature delivery, with prevalence about 12% in both white and black women.
"This study sheds important light on the intricate biological mechanisms at work during human gestation," said NHGRI Scientific Director Eric Green, MD, PhD. "In light of these findings, researchers have a renewed impetus to establish the genetic and environmental causes of low cholesterol levels because of its relevance to pregnancy."
Study limitations include an inability to generalize specific numeric thresholds for low and high TC to other populations with different profiles of gestational risk; incomplete ascertainment of potential study subjects; that the group with low maternal serum cholesterol differed from the control group in baseline characteristics, including lack of access to some sociodemographic variables known to correlate with birth outcome; and lack of generalizability to the general population.
The Division of Intramural Research, NHGRI, supported this study. The authors report no relevant financial relationships.
In an accompanying commentary, Mario Merialdi, MD, from the World Health Organization in Geneva, Switzerland, and Jeffrey C. Murray, MD, from the University of Iowa Carver College of Medicine in Iowa City, note that these findings will need to be replicated, but they may apply to a range of socioeconomic strata and have wide application.
"It is likely that the effect of low cholesterol on preterm birth could be even larger among populations with inadequate nutritional status," Dr. Merialdi and Dr. Murray write. "From this perspective, the results of the study suggest that relatively simple, affordable and culturally acceptable nutritional interventions could contribute substantially to reduce the risk of preterm birth among those populations most in need of effective preventive strategies. The results also provide insights into the pathophysiology of parturition and suggests pathways to investigate for genetic contributors to preterm labor, as well."
Dr. Murray is supported by grants from the National Institute of Child Health and Human Development and the March of Dimes.
Pediatrics. 2007;120:723–733.
So, here's about.com's information about one thing I should do: increase HDL:
http://heartdisease.about.com/cs/cholesterol/a/raiseHDL.htm
How can We Increase Our HDL Levels?
Aerobic exercise. Many people don't like to hear it, but regular aerobic exercise (any exercise, such as walking, jogging or bike riding, that raises your heart rate for 20 to 30 minutes at a time) may be the most effective way to increase HDL levels. Recent evidence suggests that the duration of exercise, rather than the intensity, is the more important factor in raising HDL choleserol. But any aerobic exercise helps.Lose weight. Obesity results not only in increased LDL cholesterol, but also in reduced HDL cholesterol. If you are overweight, reducing your weight should increase your HDL levels. This is especially important if your excess weight is stored in your abdominal area; your weight-to-hip ratio is particularly important (<0.8>
Stop smoking. If you smoke, giving up tobacco will result in an increase in HDL levels. (This is the only advantage I can think of that smokers have over non-smokers -- it gives them something else to do that will raise their HDL.)
Cut out the trans fatty acids. Trans fatty acids are currently present in many of your favorite prepared foods -- anything in which the nutrition label reads "partially hydrogenated vegetable oils" -- so eliminating them from the diet is not a trivial task. But trans fatty acids not only increase LDL cholesterol levels, they also reduce HDL cholesterol levels. Removing them from your diet will almost certainly result in a measurable increase in HDL levels. Click here for a quick and easy review of trans fatty acids and the heart.
Alcohol. With apologies to the American Heart Association, which discourages doctors from telling their patients about the advantages of alcohol: one or two drinks per day can significantly increase HDL levels. More than one or two drinks per day, one hastens to add, can lead to substantial health problems including heart failure -- and there are individuals who will develop such problems even when limiting their alcohol intake to one or two drinks per day. Click here for a quick and easy review of alcohol and the heart.
Increase the monounsaturated fats in your diet. Monounsaturated fats such as canola oil, avocado oil, or olive oil and in the fats found in peanut butter can increase HDL cholesterol levels without increasing the total cholesterol.
Add soluble fiber to your diet. Soluble fibers are found in oats, fruits, vegetables, and legumes, and result in both a reduction in LDL cholesterol and an increase HDL cholesterol. For best results, at least two servings a day should be used.
Other dietary means to increasing HDL. Cranberry juice has been shown to increase HDL levels. Fish and other foods containing omega-3 fatty acids can also increase HDL levels. In postmenopausal women (but not, apparently, in men or pre-menopausal women) calcium supplementation can increase HDL levels.
What about a low-fat diet?While Americans traditionally have ingested too much fat in the diet, and while limiting total fat in the diet is useful not only for cholesterol control but also for weight reduction, evidence is emerging that too little fat in the diet can be dangerous. A diet in which fat has all but been eliminated can result in a deficit in the essential fatty acids - certain fatty acids that are essential to life, but which the body cannot manufacture itself. Furthermore, ultra-low-fat diets have been reported to result in a significant reduction in HDL cholesterol in some individuals.
The best advice regarding fat in the diet appears to be this: 1) reduce the fat intake to 30 - 35% of the total calories in the diet - but probably no lower than 25% of total calories; 2) try to eliminate saturated fats and trans fats from the diet, and substitute monounsaturated and polyunsaturated fats instead.
What about drugs for raising HDL cholesterol?
Drug therapy for raising HDL cholesterol levels has, so far, been less successful than for reducing LDL cholesterol. Statins, in particular, are often not very effective at increasing HDL levels.
Of the drugs used to treat cholesterol, niacin appears to be the most effective at raising HDL levels. Niacin is one of the B vitamins. The amount of niacin needed for increasing HDL levels are so high, however, that it is classified as a drug when used for this purpose. Furthermore, "niacin" takes several forms, including nicotinic acid, nicotinamide, and inositol hexaniacinate - and all of these are labelled as "niacin." Unfortunately, only nicotinic acid raises HDL cholesterol, and this drug can be difficult to take because of its propensity to cause flushing, itching and hot flashes. In general, taking niacin to treat cholesterol levels should be supervised by a doctor. ( Read about niacin here.)
A three-drug regimen of niacin, cholestyramine, and gemfibrozil has been shown to increase HDL cholesterol substantially, but this drug combination can be particularly difficult to tolerate.
Now that HDL levels are attracting more and more attention, several drug companies are attempting to develop new drugs aimed specifically at increasing HDL. Unfortunately, there have been early disappointments and it will be several years before we can expect to see such drugs on the market.
Sources:
Rosenson RS. HDL metabolism and approach to the patient with low HDL-cholesterol. UpToDate. May, 2007. (UpToDate.com)
They're everywhere, and they may be worse than lard
Recent studies have suggested that trans fatty acids have a deleterious effect on cholesterol levels and the risk of heart disease, and point out that we're eating far more of these evil fats than we should, and far more than we used to.What are trans fatty acids, and where do they come from?
We're used to hearing about saturated and unsaturated fatty acids. Saturated fatty acids - which come from animal fats (meat, lard, dairy products) as well as tropical oils such as coconut and palm oils - raise the levels of LDL cholesterol. Unsaturated fats - which come from vegetable oils - in general, do not increase cholesterol levels, and may reduce them.Because saturated fatty acids were found to be bad for you a couple decades ago, the food industry wanted to switch to using unsaturated fatty acids.
Unfortunately, unsaturated fatty acids become rancid relatively quickly. To combat the instability of unsaturated fatty acids, manufacturers began to "hydrogenate" them, a process that makes them more stable. The result was a more solid and longer lasting form of vegetable oil, called "partially hydrogenated" oil.Unfortunately, when unsaturated vegetable fats are subjected to the process of hydrogenation, a new type of fatty acid is formed. This new type of fatty acid is called trans fatty acid. So when manufacturers began substituting partially hydrogenated vegetable oils for saturated fats in processed foods, they began adding - for the first time - relatively large amounts of trans fatty acids to the typical diet.
So what's the problem with trans fatty acids?
Trans fatty acids turn out to increase total cholesterol levels and LDL cholesterol levels, and to reduce HDL cholesterol levels. In other words, trans fatty acids are detrimental to cardiac health.Which is worse - saturated fatty acids or trans unsaturated fatty acids?
Both saturated fats and trans fatty acids are bad for you. Saturated fats are almost always found in foods that also contain cholesterol, so saturated fats offer a "one-two" punch to heart health. On the other hand, trans fatty acids not only increase LDL cholesterol, they also decrease HDL cholesterol. So while nobody can say yet definitively which is worse, it does appear that both are bad.Which foods contain trans fatty acids?
Fortunately, it is relatively easy to identify foods that contain relatively large amounts of trans fatty acids: margarines (the more solid the margarine, the more the trans fatty acids; stick margarines contain the most, tub margarines contain less, and semi-liquid margarines contain the least;) high-fat baked goods (especially doughnuts, cookies and cakes;) and any product for which the label says "partially hydrogenated vegetable oils" (which, it sadly appears, includes virtually all processed foods.) DrRich is particularly distressed to point out that trans fatty acids absolutely lace his two favorite food groups: french fries and potato chips. (This tragic warning also includes corn chips and many crackers.)Well, darn it, what are the good fats?
Unsaturated vegetable oils from canola, peanuts, olive, flax, corn, safflower and sunflower (as long as they have not been subjected to the process of hydrogenation) are heart healthy. These oils contain monounsaturated or polyunsaturated fatty acids that can reduce total cholesterol and increase HDL cholesterol levels. These oils also contain the essential fatty acids - specific fatty acids necessary for life but which the body cannot make itself. (These include omega-3 and omega-6 fatty acids.)So what is the health-conscious consumer to do?
There are three basic steps to reducing the amount of "bad" fat in the diet and substituting "good" fat. First, avoid the saturated fatty acids found in meat and dairy products, as well as the tropical oils (palm and coconut.) Second, avoid trans fatty acids by steering clear of commercially fried foods, high-fat baked goods, and stick margarines. Third, whenever possible substitute one of the natural unsaturated vegetable oils, listed above, in recipes calling for stick margarine, butter, or lard.Nobody ever said life was going to be easy.
Why they're important, who needs to be treated, how to treat
What is Cholesterol? What are triglycerides?
Cholesterol and triglycerides are two forms of lipid, or fat. Both cholesterol and triglycerides are necessary for life itself. Cholesterol is necessary, among other things, for building cell membranes and for making several essential hormones. Triglycerides, which are chains of high-energy fatty acids, provide much of the energy needed for cells to function.Where do cholesterol and triglycerides come from?
There are two sources for these lipids: dietary sources, and endogenous sources (i.e., manufactured within the body).Dietary cholesterol and triglycerides mainly come from eating animal products and saturated fat. These dietary lipids are absorbed through the gut,and then are delivered through the bloodstream to the liver, where they are processed.
One of the main jobs of the liver is to make sure all the tissues of the body receive the cholesterol and triglycerides they need to function.
Whenever possible (i.e., for about 8 hours after a meal), the liver takes up dietary cholesterol and triglycerides from bloodstream. During times when dietary lipids are not available, the liver produces cholesterol and triglycerides itself.
The liver then packages the cholesterol and triglycerides, along with special proteins, into tiny spheres called lipoproteins. The lipoproteins are released into the circulation, and are delivered to the cells of the body. The cells remove the needed cholesterol and triglycerides from the lipoproteins, as they are needed.
What are LDL and HDL?
LDL stands for “low density lipoprotein,” and HDL for “high density lipoprotein.” In the bloodstream, “bad” cholesterol is carried in LDL, and “good” cholesterol is carried in HDL. Most cholesterol in the blood comes from LDL. Only a small proportion is from HDL cholesterol. Thus, the total cholesterol level in the blood is usually a reflection of the amount of LDL cholesterol.Why are high cholesterol levels bad?
When LDL cholesterol levels (i.e., the “bad” cholesterol) are too high, the LDL tends to stick the lining of the blood vessels, leading to the stimulation of “atherosclerosis,” or hardening of the arteries. Atherosclerotic “plaques” cause narrowing of the arteries, and lead to heart attacks and strokes. Therefore, an elevated LDL cholesterol levels is a major risk factor for heart disease and stroke.Why is some cholesterol called “good cholesterol”?
Much evidence has now accumulated that increased HDL cholesterol levels are associated with a lower risk of heart disease, and that low HDL cholesterol levels are associated with an increased risk of heart disease. Thus, HDL cholesterol appears to be “good.”Why is HDL cholesterol protective? Nobody knows for sure, but it appears that it’s not the cholesterol itself that is good, it’s the "vehicle." There is some evidence that the HDL molecule “scours” the walls of blood vessels, and cleans out excess cholesterol. If this is the case, the cholesterol being carried by HDL (that is, the “good” HDL cholesterol) is actually “bad” cholesterol that has just been removed from blood vessels, and is being transported back to the liver for further processing. Apparently, unlike some bad humans, bad cholesterol can be rehabilitated.
Why are triglycerides the Rodney Dangerfield of lipids?
Triglycerides get little respect. Their measurement is part of a standard blood lipid profile, but for the most part doctors don’t know what to do when triglyceride levels are modestly elevated. Why is that? While high triglyceride levels have been associated with heart disease, no study has yet proven that high triglyceride levels are an independent risk factor for heart disease. So doctors don’t have the evidence they need to recommend aggressive triglyceride-lowering therapy.The problem is, patients with elevated triglyceride levels almost invariably have other major risk factors for heart disease (mainly obesity, diabetes, and/or high blood pressure), and so far it has not been possible to sort out whether the triglycerides themselves pose an independent risk.
The most difficult-to-sort-out association is that between triglycerides and HDL cholesterol. It turns out that whenever triglycerides are increased, HDL cholesterol decreases. So is the increased risk seen with high triglycerides due to the triglycerides themselves, or to the associated reduction in “good” cholesterol? So far, nobody can say for sure.
However, recent evidence strongly suggests that an elevated triglyceride level is a significant risk factor for cardiac disease - especially when it is elevated as part of the "metabolic syndrome X." Click here for a brief review of metabolic syndrome X.
Total cholesterol is considered "borderline high risk" at levels between 200 and 239, and "high risk" at levels above 240. LDL cholesterol: Optimal LDL levels are less than 100 mg/dL. Near optimal levels are between 100 and 129 mg/dL. Levels between 130 and 159 are considered "borderline high risk;" and levels between 160 and 189 are considered "high-risk;" and levels of 190 and above are considered "very high risk." HDL cholesterol: HDL cholesterol levels below 41 mg/dL are considered too low.
Additional risk factors that modify cholesterol goals:
- cigarette smoking
- diabetes
- hypertension (high blood pressure)
- low HDL cholesterol
- family history of premature heart disease
- age greater than 45 in men, or greater than 55 in women
- 10-year risk of heart attack greater than 20% The 10-year risk is calculated from a formula that takes into account the individual's the lipid levels and other risk factors. Click here for the NIH's on-line version of the 10-year risk calculator.
Based on these two items (i.e., lipid levels and presence of additional risk factors) treatment is recommended as follows:
For those with 0 - 1 risk factors:LDL target: 160 or lower. Lifestyle changes should be initiated for LDL > 159, and drug treatment for LDL > 189.For those with 2 or more risk factors:LDL target: 130 or lower. Lifestyle changes should be initiated for LDL > 129, and drug treatment for LDL > 159.
If heart disease is present or 10-year risk > 20%, or diabetes is present:LDL target: 100 or lower. Lifestyle changes should be initiated for LDL > 100, and drug treatment for LDL > 129.
What about treatment for high triglycerides?
The latest guidelines (May, 2001,) for the first time, recommend treating patients who have elevated triglyceride levels. This recommendation is based on recent analyses strongly suggesting that triglycerides are indeed an independent risk factor for coronary artery disease. The decision to treat is generally based on the triglyceride levels themselves. Normal triglyceride levels are less than 150 mg/dL. Borderline high levels are 150-199 mg/dl. High levels are 200 - 499 mg/dL, and very high triglyceride levels are greater than 500 mg/dL. For people with borderline or high triglyceride levels, treatment should emphasize weight reduction and exercise. Drugs are recommended for people with very high triglyceride levels. Most people who need treatment for high triglyceride levels have metabolic syndrome X.What other "special circumstances" deserve attention?
Patients with very high LDL cholesterol levels (greater than 189 mg/dL): These patients often have a genetic form of lipid disorder. Not only do they have a high risk of premature heart disease without aggressive therapy, but also their family members should be screened for elevated cholesterol levels, and those with high cholesterol levels also need to be treated. Patients with low HDL cholesterol levels (less than 40 mg/dL): The latest guidelines recognize low HDL levels as a strong independent risk factor for coronary artery disease. Many of patients with low HDL will have diabetes or "metabolic syndrome x." They are often overweight and physically inactive. Other causes of low HDL levels are smoking, very high carbohydrate diets (greater than 60% of calories), and drugs (anabolic steroids, progesterone, and beta blockers). Unfortunately, current drug therapy usually does not markedly increase HDL levels. Treatment for patients with low HDL levels is usually aimed at weight reduction, smoking cessation, exercise, and controlling other risk factors (such as hypertension, LDL cholesterol, and triglycerides.)Treating cholesterol and triglycerides
How are elevated cholesterol and triglycerides treated?
The primary method of treating elevated cholesterol (and triglycerides) is with diet, exercise, and weight loss. Recommended dietary changes include incorporating low total fat, low saturated fat, low dietary cholesterol, and increased starch and fiber. Physical activity should ideally consist of at least 20 minutes of aerobic exercise three to five times per week, but in fact any increase in physical activity is helpful. Patients who are obese can often significantly reduce their LDL cholesterol and triglyceride levels by losing weight.Cholesterol levels should be re-measured 3 - 6 months after undertaking these non-pharmaceutical efforts. If lipid levels are still not satisfactory, drug therapy should then be considered.
What drugs are used to treat cholesterol and triglycerides?
These drugs include four major categories:Bile acid binding resins: Cholestyramine and cholestipol – these drugs prevent the cholesterol in bile (the digestive product secreted from the gallbladder) from being reabsorbed in the gut.
Their side effects include intestinal gas and gallstones, which significantly limit their usefulness. The bile acid binding resins can also cause a decrease in absorption of other drugs, and vitamin deficiencies. In addition, these drugs can occasionally cause significant increases in triglyceride levels.
Niacin: Niacin is one of the B vitamins. When used in large doses, it can significantly reduce LDL cholesterol and increase HDL cholesterol, by mechanisms that are poorly understood. Its major side effects include skin flushing and severe itching, along with gastrointestinal disturbances. Nicacin is very effective, but because of side effects tends to be poorly tolerated.
Fibric acid derivatives: Gemfibozil and clofibrate are fibric acid derivatives. The chief benefit of these drugs is that they lower triglycerides. Their ability to reduce LDL cholesterol is much more modest. They can cause gastrointestinal side effects and gallstones.
Statins: Several statin drugs are now on the market, including lovastatin, pravastatin, atorvastatin and simvastatin. These drugs inhibit the liver enzyme HMG-CoA reductase, which significantly reduces the production of cholesterol by the liver. These drugs result in a significant reduction in LDL cholesterol, with a modest decrease in triglycerides, and a modest increase in HDL cholesterol. They tend to be well-tolerated in general, but can cause elevations in liver enzymes (which therefore need to be monitored). They can also cause a muscle disorder which can be severe in rare individuals. The muscle disorder (myopathy) is particularly likely when statins are used in combination with gemfibrozil. Click here for more on statins.
Of these drug choices, the statins are not only more effective than other categories, they also tend to be much better tolerated. Furthermore, evidence is accumulating that the aggressive use of statins can actually arrest the progression of coronary artery disease, and in some circumstances can be used instead of more invasive procedures such as angioplasty.
The treatment of abnormal lipid levels can be summarized as follows: First, dietary changes, weight loss, and exercise should be tried. If that fails to restore adequate lipid levels, then most doctors will try statins. If statins fail, or if they are not tolerated, an agent from another class of the lipid-lowering drugs can be tried.
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