HEALTH

Cholesterol Connection

Answers to your questions about this potentially life-threatening disorder.

By Wendy Haaf

Your telephone number, PIN and even credit-card account – no doubt you can reel off these figures without thinking. But if you’re like the majority of Canadians, a number that can literally have life-threatening consequences may leave you stumped.According to the 2001 Global Opinion and Awareness of Cholesterol (GOAL) survey, while 90 per cent of Canadians realized blood cholesterol plays an important role in heart health, 79 per cent of respondents didn’t know their own cholesterol levels.

Perhaps that’s because we simply don’t believe we fit the profile of a person with high cholesterol. “When you think of high cholesterol, you think of an overweight person or someone who’s physically inactive,” says Canadian golf pioneer Sandra Post. “My husband, John, is the absolute opposite. He’s tall and lean, and he gets plenty of exercise.” Nonetheless, a routine blood test revealed a cholesterol problem about 15 years ago, when the former MP was in his mid-forties.
Like Post’s husband, an estimated 44 per cent of Canadians have elevated blood cholesterol – a recognized risk factor for heart disease, stroke, peripheral vascular disease and erectile dysfunction. About half of those affected haven’t yet been diagnosed.

So who should get cholesterol testing? And exactly what do those numbers mean? Here’s our handy guide to your questions about cholesterol.

What is cholesterol?

“Cholesterol is a soft, waxy substance that’s found among the lipids or the fats in the blood,” explains Liz Helden, co-chair of the Canadian Lipid Nurse Network. Cholesterol is used in many normal processes, including the formation of cell membranes. “We need it for our bodies to work – you can’t have a level of zero,” Helden stresses.

Although cholesterol is essential, many of us have too much, a condition called hypercholesterolemia. “When you have hypercholesterolemia, that extra fat starts building up on the inside of your arteries,” explains Helden. The gunk sticks to blood vessel walls throughout the body, slowly choking off blood flow. If the coronary arteries are affected, the result may be angina. Blockages in arteries feeding the lower extremities (peripheral vascular disease) can cause leg pain and loss of mobility.

However, according to Gillian Yates, a cardiology nurse at the QEII Health Sciences Centre in Halifax, blood vessels may become more than 70 per cent blocked before a person starts to experience tell-tale symptoms. In a significant number of cases, that first clue is a whopper: an initial heart attack or stroke, about half of which prove fatal.

Who Needs Testing?

Fortunately, a simple blood test can unmask this silent disorder before the damage is done. So who needs testing? If you’re a regular good times reader, chances are you do.

New Canadian guidelines from the Working Group on Hypercholesterolemia and Other Dyslipidemias (blood fat disorders) recommend testing for men over the age of 40, women over the age of 50, diabetics, and people with documented cardiovascular disease (previous heart attack, stroke, angina or bypass surgery) or a family history of the disorder. People with two or more other risk factors – including overweight, inactivity, heavy alcohol consumption, tobacco use and high blood pressure – should also have their cholesterol levels checked.

“Do not assume that just because you’ve had a blood test that you’ve had a cholesterol level done,” Helden underlines. The nurse co-ordinator of a pediatric lipid clinic at Hamilton’s Chedoke Hospital, Helden has counselled many parents who hadn’t received cholesterol testing despite having suffered a heart attack.
If you fall into one of the risk categories, talk to your doctor about getting tested and ask how often you should receive regular re-testing. And if you have gained weight or have been diagnosed with diabetes (a disease that’s often associated with abnormal blood fat levels) since your last blood work, consult your physician about scheduling another cholesterol test.

When you receive the results of your test, you’ll probably be given at least three different numbers: total cholesterol, LDL and HDL. While it was once thought that high cholesterol alone was associated with heart attack risk, doctors now know that total cholesterol doesn’t tell the whole story. “Today, we tend to look at the ratio of LDL and HDL,” explains Dr. David Jenkins, a spokesperson for the Heart and Stroke Foundation, and professor of medicine and nutritional science at the University of Toronto.

LDL: ‘Lousy’ Lipoprotein

Sometimes called “bad” cholesterol, low-density lipoprotein (LDL) molecules form a fleet of railway cars that carry cholesterol from the liver (where more than 75 per cent of cholesterol in the body is made – the remainder comes from fatty foods in our diet) to cells throughout the body. It’s the LDL cholesterol that spreads fatty plaque along the artery walls: the more LDL, the greater the likelihood you’ll develop narrowed blood vessels.

“If you’re in good shape and otherwise good health, your LDL number should be 4.1 mmol/L or below,” says Dr. Jenkins. However, if you already have heart disease or diabetes, your doctor will set your target LDL much lower – 2.5 mmol/L.

HDL: ‘Healthy’ Lipoprotein

On the other hand, when it comes to high-density lipoprotein (HDL), the bigger the number, the better.

“HDL can protect against cardiovascular disease in a number of ways,” explains Dr. Bernardo Trigatti, an assistant professor of biochemistry at McMaster University in Hamilton, Ont. First of all, HDL seems to “scrape away” cholesterol from atherosclerotic plaque, carrying it back to the liver. “HDL may also carry antioxidants – for example, vitamin E is carried by HDL in the blood. HDL also appears to have some beneficial effects on blood vessels themselves.”
So what constitutes a healthy HDL level? “You want to have it as high as you can,” says Dr. Jenkins. “Certainly, 0.9 mmol/L is considered to be the lower limit,” he says. “If you’re one of those lucky people who have an HDL level in the 1.6 mmol/L range, you can tolerate a higher LDL level.”

Triglycerides

“Another number we look at is triglycerides,” says nurse Gillian Yates. While triglycerides – another type of blood fat – aren’t a form of cholesterol, high levels have been implicated in heart disease. “For most people, triglyceride levels should be below 2.0 mmol/L.” (If you’re diabetic, careful control is essential, since high blood sugars can send your triglyceride levels soaring.)

How Healthy Habits Help

“Lifestyle factors, like diet and exercise, can reduce your cholesterol levels between seven and 15 per cent,” Yates says, thereby reining in your risk of heart disease by as much as 25 per cent. If your levels are only mildly elevated and you’re otherwise healthy, your doctor may suggest trying to bring your cholesterol under control by changing your diet and re-testing within three to six months.

“The most important dietary factor in terms of plasma (blood) cholesterol levels is total fat in the diet and then saturated fat,” says Dr. Leonard Piché, associate professor of nutrition at Brescia University College in London, Ont. Health Canada recommendations for healthy individuals suggest keeping fat intake to 20 to 30 per cent of total energy intake (10 per cent or less from saturated fats, which include full-fat dairy and red meats, as well as palm or coconut oil), with emphasis on ‘heart-healthy’ fats such as olive oil and nuts. (Nuts also contain plant sterols – substances also found in leafy greens – that can help reduce cholesterol levels.)
“We used to say don’t eat nuts because they’ll make you fat,” says Dr. Jenkins. “Now we’re saying, on the other hand, they may raise the healthy cholesterol level and lower the bad.” The trick? “Keep consumption within your calorie count.”

Fibre is another dietary component that can bring down blood cholesterol. (For the first time, proposed Health Canada guidelines contain specific recommendations about fibre intake, says Dr. Piché: a minimum of 21 grams per day for women over the age of 50, and 30 grams per day for their male counterparts.) “We used to say that all fibre was good, but now we’re being more specific,” says Dr. Jenkins. “Oat bran, oats, barley and psyllium all contain the sort of ‘sticky’ fibre that lowers cholesterol.”

“Soy protein has also been found to lower serum cholesterol,” Dr. Jenkins adds. (At least one study suggests that substituting good-quality protein – not necessarily soy – for some of your carbohydrates may also help reduce triglyceride levels.) “You can now get soy hot dogs and soy burgers. These foods have two advantages: low saturated fat and soy protein.”

Omega-3 fatty acids – found in cold-water fish – may also improve your cholesterol levels.

Reducing saturated fat, eating lots of fibre-rich foods and watching your calorie intake will also help bring bad blood cholesterol levels within healthy bounds by keeping your weight down. “Excess body weight lowers HDL levels,” Yates observes, in addition to driving up damaging LDL.
Adding aerobic exercise (at least 30 minutes per day) to your prescription for heart health will not only help you maintain a healthy weight, it can brighten your blood cholesterol picture even if you can’t shed extra pounds. “If you are overweight, losing weight will help push your LDL levels down, but exercise also keeps your cardiovascular system fit, increases your HDL levels and alleviates stress,” Helden explains.

Cutting out cigarettes and cigars is another important step in bringing your risk into line. “Smoking decreases HDL levels,” says Yates. And while a glass of wine with dinner may do your heart good, don’t tipple too often – one drink per day for women and two for men may moderate LDL levels, but alcohol and sugar tend to send up your triglycerides.

When Diet Isn’t Enough

Even after you’ve stubbed out your last cigar, substituted soy burgers for ground beef and chucked the full-fat cheese, your cholesterol levels still may not fall far enough.

“We eat very well and we couldn’t be any more active than we are – we did everything we possibly could,” says Sandra Post. However, her husband’s blood cholesterol barely budged. (It’s possible John’s high cholesterol is genetic, but he doesn’t know whether he inherited the problem from one of his biological parents because he was adopted.) “He had to go on medication. Why take the chance?”
If you are considered ‘high risk’ because of diabetes or a previous heart attack, your doctor will probably recommend starting medications immediately – even before giving lifestyle changes a chance to work.

“Today, high cholesterol doesn’t have to be the kiss of death,” concludes Sandra Post.

Statins are the drugs used most commonly to control cholesterol. They have been shown to reduce the risk of heart attacks and other cardiovascular events by about one-third (in people who’ve had previous heart attacks, they cut the chance of dying of a second attack by 40 per cent). Statins seem to protect against heart attacks in at least two different ways: not only do these drugs interfere with cholesterol production in the liver, they may also render atherosclerotic plaque less prone to rupture. (About 90 per cent of heart attacks and strokes result from a piece of plaque breaking off and lodging in a blood vessel.)

While statins are usually safe, like any drug, they do have the potential for serious side-effects and drug interactions. Your doctor will suggest follow-up blood tests several weeks after you start taking a statin medication to determine whether the drug is working and ensure it isn’t adversely affecting your liver or muscles (which occurs in only about one per cent of patients). Any time a physician prescribes another medication for you – such as an antibiotic – ensure he or she knows you’re taking a statin. And to make the most of your medication, take your pills as directed: since cholesterol is made in the wee hours of the morning, the drugs are most effective when taken in the evening.