Volume 2, Number 2: Summer Solstice, 2000

Cholesterol PART II - BC Endocrine Research Foundation

Dr. Eric G. Norman PhD

Staff Member with the Division of Endocrinology University of British Columbia, Vancouver, B.C.

Improving Plasma Lipid Levels Lifestyle Modifications

ELEVATED PLASMA LIPID LEVELS

In Part I of this article you were introduced to a variety of blood plasma lipids, including cholesterol. We discussed what these plasma lipids were and how to determine whether your plasma lipid levels represent a risk for heart disease. If your blood test shows you have elevated lipids and your physician feels it represents a risk for heart disease the obvious solution is to try to lower them. The healthiest, simplest and cheapest ways to do this are to improve your diet and exercise regimen and stop smoking. Any one of them alone will have benefits but ultimately they are more effective when combined. Here in part II of the cholesterol saga we will address lifestyle modifications.

DIET

The American Heart Association recommends your diet consist of 50% of the calories in the form of carbohydrate, 20% protein and no more than 30% fat. Of that 30% fat less than 10% should be saturated, 10-15% monounsaturated and 7-10% polyunsaturated. Cholesterol intake should be restricted to less than 250 mg/day. One egg yolk for example, depending on the size, will have approximately 210-250 mg of cholesterol. In people with established coronary artery disease (CAD) less than 7% saturated fat and less than 200 mg/day cholesterol is recommended. Most packaged foods now have the lipid (fat) composition breakdown on the package labeling so you can do your own calculations to estimate how much of each type of fat you are consuming.

Where does cholesterol come from?

Cholesterol is either synthesized in your body or absorbed from the dead animals or animal products that you eat. Vegetables DO NOT contain cholesterol. Cholesterol sources include red meat, chicken, fish, seafood, eggs or dairy products. If you want to eliminate all cholesterol from your diet eliminate animal products. Then it is simply a matter of your body synthesizing the cholesterol it needs. If you are not willing to do that then you have to accept that there will be some cholesterol in your diet. It is then your decision which of these animal foods and how much of them you eat. This decision should be made by making note which have the most cholesterol, as well as saturated fat, and reducing the amounts of these food in your diet accordingly. Although vegetable foods do not contain cholesterol they do contain some amount of each of the three types of fat; saturated, polyunsaturated and monounsaturated. Although saturated fat are usually not a concern with vegetable foods, some do contain high levels of saturated fatty acids. Palm oil, palm kernel oil and coconut oil fall into this category and should be avoided. While dietary cholesterol is often pointed to as a major problem, which it is, consider this. Saturated fatty acid consumption has been shown to be a stronger predictor of heart disease than cholesterol so be sure to emphasize reduction and moderation when consuming foods high in either of these. These really are only some basics and it is entirely up to you to educate yourself and make conscious food choices.

Reducing Fat In The Diet

A typical Western diet contains about 35 to 40% of calories as fat. By lowering this to 30% (referred to as a Step 1 Diet) it has been found that total plasma cholesterol can be reduced by 5-10%. In another study it was found that reducing dietary fat from 43% to 25% (referred to as a Step 2 Diet) resulted in a 17% reduction of total cholesterol and a 23% reduction of LDL cholesterol. Lowering fat intake to 10% in a different study, combined with other lifestyle modifications, resulted in a 25% reduction in total cholesterol, an average weight loss of 10 kg and angiographic regression of coronary artery disease. I present these examples as evidence that varying degrees of diet change, especially reduced fat, when combined with other lifestyle modifications can be effective in reducing plasma cholesterol in most cases. It requires effort but the benefits are worth it. In cases where dietary fat is reduced to 10% of total calories care should be taken to ensure that overall nutrition is not compromised.

As stated earlier, reducing saturated fats should be the main focus of reducing dietary fat, since saturated fats have the greatest effect on elevating plasma cholesterol. Polyunsaturated fats, found mainly in vegetable oils, do not increase plasma cholesterol as much as saturated fats. However, since long-term effects of consumption of large amounts of polyunsaturated fats are not known it is recommended that no more than 7% of calories consist of these fats. Be wary of vegetable fats hardened by the hydrogenation process (e.g., margarine) converting them to trans fatty acids as this makes them comparable to saturated fatty acids in terms of their effect on plasma cholesterol and the progression of heart disease.

It is generally agreed that the monounsaturated fats are the best for you, and produce the least deleterious effect on plasma lipids. If monounsaturated fats are substituted for saturated fats, total plasma cholesterol is lowered without affecting the levels of HDL (good stuff). Olive oil is agreed to be one of the best forms of oil for food preparation. You may be familiar with the Mediterranean diet which been found to result in lower incidences of heart disease as well as less cancer. Key components of this diet include plenty of fruits, vegetables, legumes and grains; olive oil as a main source of fat; moderate dairy consumption (cheese and yogurt); moderate consumption of fish and poultry; low intake of red meat and meat products; zero to four eggs per week; moderate alcohol consumption. This type of diet is an excellent starting point for people wishing to make a change in their diet. Canola oil also has high levels of monounsaturated fats but is often made from genetically modified forms of the plant, is not as heat stable as olive oil and some reports suggest potential cancer causing effects. I personally would recommend using cold pressed virgin olive oil which has hundreds of years of tried and true success.

Some foods are thought to lower the plasma cholesterol levels. Garlic and walnuts for example have been found to cause modest reductions in plasma lipids. Psyllium, guar gum, oat bran, rice bran and split peas are all high in a fibre that produces a sort of gel matrix in the intestine and binds bile acids which then exit the body in the stool along with the fibre. You may recall that cholesterol is used to synthesize bile acids and as the body replaces the excreted bile there is a gradual lowering of the blood plasma cholesterol. Different amounts of these foods are required to achieve the same effect. Psyllium and guar gum are very concentrated sources of fibre (3 teaspoons per day) while the oat bran, rice bran and split peas are required in larger amounts (approx. 1/2 cup) to achieve the same effect.

Flax oil is an excellent source of the omega-3 fatty acids which are known to improve plasma lipid profiles. Flax oil is so effective in fact that it is banned from being used in clinical trials investigating lipid lowering medications because it interferes with the interpretation of the results. Flax oils can be taken in the form of a capsule, typically 1000 mg, or purchased in 8-12 ounce bottles. It should be stored in the dark, preferably in the fridge. I use the liquid form in salad dressings or in place of butter for vegetables. It is not heat stable and should not be used for baking or frying foods.

Anitoxidants

If you recall Part I of this series you may remember that oxidation of LDL is central to the progression of atherosclerosis. The theory, therefore, is that by including antioxidants in our diet (eg. Vitamin E, C, A), either in food or as supplements, we should be able to reduce the oxidation of LDL and slow the progression of atherosclerosis. Research trials investigating this have produced conflicting findings, some showing a benefit while others show none at all. The most recent and perhaps the best run trial to date that investigated vitamin E was the Heart Outcomes Prevention Trial (HOPE) that randomized over 9000 men and women to either 400 IU Vitamin E or placebo for almost five years. In this study there was no significant difference in the number of heart attacks or strokes or deaths due to heart disease between the two groups. It has been argued that antioxidants work best when they are used in combination to improve the stability and efficacy of each other and this trial did not incorporate this into the protocol. Virtually all studies have agreed, HOPE included, that there is no harm in taking doses of vitamin E in the 400 to 800 IU range and other benefits may be derived that have not been measured. The same is true for vitamin C and A.

Alcohol. There is evidence that alcohol in moderation can actually raise your HDL and reduce the risk for coronary artery disease and results in lower total mortality. Moderate consumption is defined as no more than two drinks per day; a drink being a 6 ounce glass of wine, a 12 ounce beer or a 1 ounce shot of liquor. The amount should be even less for women and smaller men. The benefits are quickly replaced by health risks and increased mortality as the consumption exceeds these amounts. In cases of hypertension alcohol is often contraindicated and a physician should be consulted if a patient has any doubts about the consumption of alcohol. Especially in cases of high triglycerides or pancreatitis alcohol should be avoided.

Folic acid. Relatively recently it has become apparent that high levels of homocysteine represent a significant risk for heart disease and stroke. Although the precise mechanism isn’t clear the solution, it turns out, is fairly simple, folic acid. Eating foods high in folic acid or supplementing your diet with approximately 400 micrograms of folic acid daily will help to keep homocysteine levels in a safe range. Foods high in folic acid are numerous and include a range of beans, cereals, fruits (orange, cantaloupe, pineapple), vegetables (beets, broccoli, cauliflower, corn, okra, turnip greens, asparagus) and brewer’s yeast.

Exercise. We will discuss here the direct effects of exercise on plasma lipids although other benefits also deserve mention as they impact on cardiovascular wellness and general health. There is a growing body of evidence that links regular physical activity with a decrease in heart disease and improved plasma lipid profiles. Increases in HDL (good lipids) and reductions in plasma triglycerides (bad lipids) result from regular moderate exercise. Although less consistent, there are generally reductions in LDL cholesterol and shifts in LDL from small dense particles to larger particles (a beneficial change). There is also increased lipoprotein lipase (LPL) activity, which improves removal of fat from the blood. In conjunction with a low-fat diet, regular exercise in overweight individuals provides the greatest improvements in the lipid profile.

In addition to these benefits exercise has been correlated with reduced mortality following a heart attack (MI). There is also the benefit of increased oxygen uptake in the lungs and reduced oxygen demands of the muscles of the heart. Beneficial changes are also seen in hormonal, respiratory, neurologic and metabolic function. Exercise can also aid in the control of diabetes and obesity as well as lowering blood pressure in most individuals. Positive changes are also seen in carbohydrate metabolism, adipose tissue (fat) distribution and insulin sensitivity. And if that isn’t enough, exercise has been shown to improve indexes of psychological functioning, reducing depression and increasing self-confidence and self-esteem.

How Much Is Enough?

The general rule is that benefit can be made from regular moderately intense exercise performed approximately 4 to 6 times a week for 30-60 minutes. This should include both aerobic activity such as brisk walking, running, cycling and swimming as well as resistance workouts 2 to 3 times a week using free weights or gym equipment. Even though resistance exercise has only a minimal impact on heart disease it has known benefits such as maintaining muscle mass, strength, bone mineral density and functional capacity. There are those who will say that they cannot fit 30 to 60 minute workouts into their busy day. It is possible to do shorter durations with the time you have available and do these several times a day (eg.15-20 minutes 2 times a day). There is evidence that many of the benefits will still be derived if this approach is taken.

Precautions

The general rule is that benefit can be made from regular moderately intense exercise performed approximately 4 to 6 times a week for 30-60 minutes. This should include both aerobic activity such as brisk walking, running, cycling and swimming as well as resistance workouts 2 to 3 times a week using free weights or gym equipment. Even though resistance exercise has only a minimal impact on heart disease it has known benefits such as maintaining muscle mass, strength, bone mineral density and functional capacity. There are those who will say that they cannot fit 30 to 60 minute workouts into their busy day. It is possible to do shorter durations with the time you have available and do these several times a day (eg.15-20 minutes 2 times a day). There is evidence that many of the benefits will still be derived if this approach is taken.

If you are under forty years of age and have no coronary risk factors then you should be able to start a moderate exercise program on your own. Otherwise it is recommended that you consult your physician, have appropriate medical evaluation, possibly exercise testing, and make arrangements to plan a program that will allow you to gradually increase the duration and intensity of exercising. No matter what your age is, always consider your prior level of activity before starting a program and be sure to start off gradually, listening very closely to your body. Educating yourself about the safest and most efficient ways to achieve your exercise goals is invaluable and there are many excellent programs out there to assist you.

SMOKING

It cannot be stressed enough how detrimental smoking is to a person’s health. In 44 developed countries taken together smoking was responsible for 24% of the deaths in men and 7% of the deaths in women. The average loss of life due to smoking is 8 years and that does not include the loss of quality of life. Smoking can kill in 24 different ways. You may be thinking that smoking only affects the lungs but think again. Smoking devastates the entire vascular system. It doubles to quadruples the risk for coronary heart disease (CHD) events and works synergistically with high blood pressure, high cholesterol and diabetes to increase this risk. Smoking appears to accelerate the atherogenic process in a dose-dependent and duration-dependent manner, especially in the medium and large vascular beds. Second hand smoke is just as bad if not worse and contains more than 4,000 chemicals of which 42 are known or suspected to cause cancer.

Lipids. Smoking increases the bad blood lipids (TC, LDL, TG, VLDL) and decreases the good lipids (HDL) compared to non-smokers. This is directly dependent on the smoking intensity (light, moderate and heavy) and partly related to the high circulating free fatty acids caused by smoking. Some of these effects are documented in healthy adults and children who were exposed to second hand smoke. In addition, smoking impairs chylomicron clearance and accelerates oxidation of LDL promoting plaque formation.

Blood Pressure. The increases in blood pressure and heart rate from smoking are likely mediated by nicotine. It has been shown that nicotine gums and intravenous nicotine both affect blood pressure (10-15 mmHg) and pulse rate (10-15 beats per minute). These hemodynamic effects contribute further to the atherogenic effects of smoking. Impaired ability of the blood vessels to respond to vasodilators is documented for smokers as well as those exposed to second hand smoke.

Stopping Smoking. Having summarized the damage that smoking does I must stress that it is never too late to stop smoking. Research has shown that half of the risk for nonfatal heart attack disappears in the first year once smoking is stopped and after 2 to 3 years the CHD risk approaches that of non-smokers. Surprisingly, this recovery is independent of smoking duration or intensity. In some studies HDL (good lipid) has been seen to increase within 30 days of stopping and can increase as much as 0.2 mmolesL (20-30%). LDL (bad lipid) has also been observed to decrease and stopping smoking may also promote inactivation of acute atherosclerotic lesions. It really is never too late to quit smoking and there are many programs available to provide assistance for those who wish to stop. Simply ask your physician for advice on how you can get started on stopping.

Lifestyle Summary. The best advice when it comes to making lifestyle modifications is make changes gradually and not to expect one single change to make all the difference. Picture a number of small changes with each one making its own contribution, not only to a lower plasma lipid reading, but more importantly, to a healthier body and a better quality of life.

Eric Norman is a research scientist investigating heart disease in post-menopausal women using ovarian hormone therapy and in type II diabetics.

References

  1. Manual of Lipid Disorders. Reducing the risk for coronary heart disease. Antonio M. Gotta Jr.; Henry J. Pownall. Second Edition. Publisher: Williams and Wilkins. 1999.
  2. Disorders of Lipid Metabolism. Chapter 23.Mahley, R.W.; Weisgraber, K.H.; Farese, R.V. in Williams Textbook of Endocrinology, Ninth Edition. Editors: Wilson,J.D.; Foster, D.W.; Kronenberg,H.M.; Larsen,P.R.. Publisher: W.B. Saunders Company. 1998.
  3. Advanced Nutritional Therapy. Cooper, K.H.(M.D., M.P.H.). Thomas Nelson Publishers. 1996.
  4. 8 Steps To A Healthy Heart. Kowalski, R.E. Warner Books Inc. 1992.

Get Involved

Help make a difference

B.C. Endocrine Research Foundation

#4116 - 2775 Laurel Street
Vancouver, B.C.
V5Z 1M9

Email: aleta.allen@vch.ca
Tel: (604) 875-5929

Board of Directors

President: Dr. Marshall Dahl
Vice-President: Dr. David M. Thompson

Board Members: Dr. Keith Dawson, Dr. Jason Kong, Dr. Ehud Ur, Dr. Jerilynn Prior, Dr. Tom Elliott, Dr. Breay Paty, Dr. Sandra Sirrs

Bookkeeper: Nancy Walker

Administrator: Aleta Allen