cholesterol reduction

Introduction

Dietary fats and cholesterol receive considerable attention from the medical community, food manufacturers and individuals concerned with their health. Research conclusively demonstrates that elevated cholesterol in the blood is a significant, and modifiable, risk factor for heart disease. Subtypes of cholesterol may be independent risk factors or protective for heart disease. The role of triglycerides is less well defined, but many feel they also contribute to heart disease. Obesity is also a known promoter of heart disease. Dietary fat contributes significant numbers of calories to Americansí daily diets, to obesity and to several forms of cancer.

American Heart Association Guidelines

The American Heart Association publishes specific guidelines for dietary recommendations for fat and cholesterol. The AHA also recommends dietary and medical interventions for people with elevated cholesterol. The public now can calculate approximate daily intake of calories, total and unsaturated fat, cholesterol and fibre as a result of recent FDA food labelling mandates. Despite the wealth of information available on the subject, many people are confused by the bold claims and confusing details regarding control of cholesterol. American Family Physician also has Patient information: "Goals for Lowering Your Cholesterol".

NIH National Heart, Lung and Blood Institute Clinical Guidelines

The NIH National Heart, Lung and Blood Institute Clinical Guidelines from the Expert Panel on Detection, Evaluation and Treatment on High Blood Cholesterol in Adults published in April 2001 have information for both health care professionals and the lay public. It also includes a 10 year risk calculator for heart disease and links to all available cholesterol education resources.

FAA Policy on Cholesterol Screening

In the early 1990's, the FAA considered measuring blood cholesterol in pilots in their Notice of Proposed Rulemaking changing FAR Part 67. Although no disqualification was recommended for elevated cholesterol levels, values above 300 mg% would have triggered a cardiovascular evaluation. Numerous objections from many interested parties were validated and the FAA dropped this proposal from the new FAR Part 67 adopted in September 1996. No blood testing is routinely required nor is any level of cholesterol disqualifying. However, nearly every cardiovascular condition requiring evaluation for the FAA includes a mandatory report of the pilotís cholesterol, triglycerides and glucose levels.

Cholesterol Monitoring for Pilots

The control of blood lipid levels (cholesterol and triglycerides) is an important step in controlling heart disease, stroke and heart failure. Anyone interested in their long-term health and well-being should attempt to reduce their lipid levels if elevated. Pilots traditionally have had some reluctance to monitor lipid levels and intervene against elevated levels for fear of adverse effects on their medical certificate. This reluctance is unjustified. Many methods for lowering cholesterol exist without using medication. Cholesterol control with dietary changes and nutritional supplements is not reportable on the FAA Airman's Medical Application.

The FAA currently approves most lipid lowering medications on the market in pilots who tolerate them well without side effects. FAA physicians look favourably on pilots who are taking active steps to control their cholesterol levels as part of any cardiovascular health program. How should pilots address this issue?

Most physicians recommend obtaining a blood sample to determine baseline cholesterol, triglycerides and possibly blood sugar levels. To provide a proper sample, one should fast (nothing to eat or drink except water) for 12-14 hours before the blood is drawn. Abstinence from alcohol for several days prior to the test may give lowered triglycerides levels. Dietary changes in the few days before testing have little effect on cholesterol levels. Monitoring cholesterol levels after instituting medication or dietary changes is not recommended at intervals less than several months. Ideally, each blood test for lipids should be done at the same laboratory to give greater consistency in comparing results.

Cholesterol Types

Most reports of blood lipids are divided into several components. The total cholesterol is always reported. Levels below 200 mg% are desirable, lower in some medical conditions. The total cholesterol (TC) is divided into the high density lipoproteins (HDL), low density lipoproteins (LDL) and very low density lipoproteins (VLDL). Triglycerides (TG) are reported separately.

HDL is the "good cholesterol". HDL may actually aid in reversing cholesterol deposits on the lining of the blood vessels. Higher levels seem to give some protection against heart disease while levels below 30 mg% are an independent risk factor for heart disease. Frequently a ratio of the TC to the HDL is reported. A TC/HDL ratio of less than 5.0 is desirable and less than 3.5 is optimum. As the ratio rises, so does the risk of heart disease.

LDL is the "bad cholesterol". Levels under 130 mg% are acceptable while those above 160 mg% indicate the need for treatment. Many times, treatment is appropriate at significantly lower levels of LDL. For those people with known coronary artery disease, many physicians are recommending lowering LDL cholesterol levels below 100 mg% to possibly reverse cholesterol deposits in the arteries. VLDL is infrequently reported as the significance of this factor is not established.

Triglycerides (TGs) should also be under 200 mg%, but the significance of elevated levels is not fully explained. Other components of the lipid profile that are less frequently measured, but associated with heart disease, include Apoprotein B and lipoprotein (a).

Risk Factor Reduction

Many steps are available for the person with elevated cholesterol interested in reducing the risk of heart disease.

First, the individual should reduce daily cholesterol intake to less than 200 mg while fats should make up less than 30% of total calories. Many diet experts suggest a diet containing approximately 20% fats to lower the risk of several diseases. Diets rich in grains, fruits and vegetables are ideal. Avoiding unmodified dairy products, rich meats and saturated fats and oils found in many processed foods reduces fat and cholesterol. Low fat alternatives are available. Reading the nutritional labels on foods is enlightening and possibly surprising. Poly- and mono-unsaturated oils may actually lower cholesterol.

Publicity for the high protein, low carbohydrate diets (Atkins) in November 2002 at the American Heart Association Annual Scientific Meeting generated much confusion about a proper diet. For information on the AHA's current position, see the AHA Statement on High-Protein, Low-Carbohydrate Diet Study Presented at Scientific Sessions.

Exercise is an important step in lowering total cholesterol and raising HDL cholesterol.

Smoking cessation will also raise HDL. One to two ounces of alcohol (a 12 oz. beer, one glass of wine or a single mixed drink) daily may be helpful in improving cholesterol. More than this amount is harmful.

Soluble fibre and omega-3 fatty acids will improve cholesterol profiles. Good sources of omega-3 fatty acids include fatty fish products (salmon) and flax seed oil. Flax seed oil is an excellent source of essential fatty acids in the diet, including the very desirable omega-3 and omega-6 fatty acids.

Adequate dietary intake of certain vitamins including niacin, vitamin E, some B vitamins and folate may be protective. The VFS article on Vitamins and Minerals has expanded discussions on each of these essential dietary components. Also see an article in American Family Physician on Alternative Therapies: Part II. Congestive Heart Failure and Hypercholesterolemia. The Agency for Healthcare Policy Research did not find evidence for reduction in heart disease with use of antioxidant supplements in its Evidence Report/Technology Assessment: Number 83, "Effect of Supplemental Antioxidants Vitamin C, Vitamin E, and Coenzyme Q10 for the Prevention and Treatment of Cardiovascular Disease"

Fibre

Increasing fibre intake in the diet may also lower cholesterol. Research indicates that soluble fibre may interfere with the absorption of cholesterol in the intestine and significantly lower cholesterol and triglycerides levels. Fruits, grains and vegetables are high in fibre. The average American diet includes about 5-10 grams of fibre daily. The recommended amount is 25-35 grams.

Many people find it hard to increase their fibre intake to meet these recommendations with non-medicinal nutritional supplements. These supplements may be very effective in lowering cholesterol. They are not reportable to the FAA or your AME as a medicine. Consult with your personal physician or a preventive medicine specialist for details on available supplements. The Virtual Flight Surgeons article on Herbal Medications and Nutritional Supplements has an expanded discussion of the role of dietary fibre. Also see an article in the Federal Air Surgeon's Medical Bulletin by Dr. Glenn Stoutt, Just About Everything You Need to Know About Fibre in Your Diet

Next, the person should avoid all tobacco products and participate in a program of regular aerobic exercise. Discuss an exercise program with your physician if you do not already engage in regular activity. These steps will lower the total cholesterol and raise the HDL. The TC/HDL ratio may drop significantly. Weight reduction will also help lower total cholesterol. See the VFS articles on Smoking Cessation and Tobacco Abuse, Obesity and Weight Control. Nutritional supplements and vitamins may also play an important role in cholesterol reduction.

Cholesterol Lowering Medications

For those who continue to have elevated lipids despite non-pharmacological steps or those who have other risk factors for heart disease or marked elevated lipid levels, intervention with medications may be prudent. Several categories of medications are available. The selection should be determined after discussion with your physician about your lipid profile, co-existing medical conditions, family history, lifestyle and costs and side effects of the medications.

HMG Co-A Reductase Inhibitors - Statins

The HMG Co-A reductase inhibitors, also known as "statins", are the most widely used class of medication to lower cholesterol. They work by blocking an enzyme that converts dietary fats into cholesterol in the liver. The statins are relatively recent entries into the market, but their popularity is due to their excellent tolerance and tremendous effectiveness. They have very few side effects and may be taken once daily in most cases. There is some potential to elevate liver enzymes so some physicians will add liver testing to repeat cholesterol testing. The major drawback, as with any new and successful drug, is their cost. Examples include pravastatin (Pravachol), lovastatin (Mevacor), simivistatin (Zocor), fluvastatin (Lescol) and atorvastatin (Lipitor). The newest statin drug is Crestor (rosuvastatin) which is authorized by the FAA.

The FDA announced a recall of one "statin", cerivastatin (Baycol), on August 8, 2001. Manufacturer Bayer AG announced that 31 deaths have been associated with its' use, primarily in the high dosage form or when combined with another cholesterol medication called gemfibrizol. See the FDA Baycol Information Page.

An article in the May 2002 issue of Neurology raised the possibility of the statin medications leading to an increased risk of neuropathy (nerve damage). The study was conducted by a Danish physician, but the results have yet to be reproduced in the US.

Another potentially significant side effect of some statins is myositis (muscle damage, weakness and pain). The October 1, 2002 issue of Annals of Internal Medicine published an article documenting muscle damage in four patients using statins who had normal levels of CK, an enzyme usually used to monitor for myositis. The National Heart Lung and Blood Institute published Guidelines and a Clinical Advisory on the use of statins. Overall, the benefits of statins far outweigh the risks of their use in most people with elevated cholesterol.

Niacin

Niacin is a B vitamin that is effective in lowering LDL, TC, TG and TC/HDL ratio. It also significantly raises HDL. All of these effects are desirable. The major advantage is that it is inexpensive and effective. The disadvantage is that it may cause skin itching and flushing after taking even moderate doses. This effect is reduced by taking a single aspirin 30 minutes prior to the niacin.

Liver injury is also possible as in the statins and monitoring of liver function is recommended. Crystalline niacin does not seem to cause liver injury, which is primarily associated with long acting or slow release forms of niacin. Recent products that release niacin slowly to decrease the flushing are Niaspan, Slo-Niacin, Niocor and Nicolar, but require regular monitoring of the liver to detect early damage. Niacin doses of 200-400 mg per day may be effective in lowering cholesterol levels, while dosages of up to 2000 mg per day may be used in serious cases of elevated lipids. Niacin is available as a nutritional supplement without a prescription. See the VFS article on Vitamins and Minerals for more information on niacin benefits.

Bile Acid Sequestrants

Bile acid sequestrants act much like soluble fiber in the intestine. These products bind bile acids that allow dietary fat to be absorbed and processed into cholesterol. They have been on the market a long time. They are in powder form and may need to be mixed with juice to take in a palatable form. The major limiting factor is their tendency to cause stomach upset, bloating and flatulence. These side effects are minimized by gradually increasing the dosages. Bile acid sequestrants may also block the absorption of some medications. They may raise TG levels slightly. Examples include cholystramine (Questran) and colestipol (Colestid).

Gemfibrizol and Clofibrate

Fibric acid derivatives were some of the earlier triglyceride lowering medications. These medications are effective in lowering triglycerides, with much less effect on cholesterol. The major side effect is the potential for gallstones and gallbladder disease. Gemfibrozil (Lopid) or clofibrate (Atromid-S) have variable effects on LDL cholesterol. Use of gemfibrozil in combination with high dosages of the FDA recalled cerivastatin (Baycol) has been linked to patient deaths. Gemfibrozil used alone has not been associated with deaths.

Ezetimibe

Zetia (ezetimibe) is in a new class of cholesterol and triglyceride lowering medication that can be used with other medications for the same condition. It was approved by the FDA in October 2002 authorized for use in pilots by the FAA in October 2003. It's mechanism of action is to selectively inhibit absorption of cholesterol from the small intestine, reducing uptake by 54%. See a review of this medication in American Family Physician.

FAA Reporting Requirements

The FAA will approve all medication categories listed above after a ground testing period of several days free of side effects. Reporting of the use of the medication is required at the time of the next FAA medical examination. Report in Section 17 of the FAA Application for Airman's Medical Certificate, Form 8500-8, under Medications Used.

Controllers should report to the Regional Flight Surgeon before returngin to safety sensitive duty. Use of fibre, non-prescription niacin and nutritional supplements are not reportable to the FAA.

New Food Products to Lower Cholesterol

A new butter-margarine substitute which may lower cholesterol levels has been approved by the FDA recently. The product, called "Take Control" from Lipton contains unsaturated fat chains, called sterols, derived from soybeans. These phytonutrients are acknowledged as "Generally Recognized as Safe" and may help lower cholesterol levels.