It's well known that cutting saturated fat, found in meat and dairy products, can help lower elevated LDL (bad) cholesterol in the blood, a risk factor for heart disease.
And if your daily diet also includes foods such as oats, almonds, soybeans and plant-sterol enriched margarine you'll lower your LDL cholesterol even more.
This cholesterol-busting food combo – known as a diet portfolio – has been well studied by David Jenkins, professor and Canada Research Chair in metabolism and nutrition at the University of Toronto and director of the Risk Factor Modification Centre at St. Michael's Hospital in Toronto.
His portfolio diet has been shown to slash LDL cholesterol by 28 per cent, lower blood pressure and decrease markers of inflammation in the body.
Now, according to a study published this week in the Canadian Medical Association Journal, adding monounsaturated fat – think avocado, nuts and olive oil – to the portfolio diet can further improve cholesterol levels.
The diet lowered bad cholesterol by 35 per cent while also raising HDL or "good" cholesterol.
High levels of HDL seem to protect against heart attack. HDL carries cholesterol away from the arteries and back to the liver, where it's broken down. It's also thought that HDL removes excess cholesterol from fatty plaques in arteries, slowing their buildup. (HDL targets for men and women are greater than one millimole per litre and 1.3 mmol/L, respectively. An HDL of 1.5 mmol/L or greater for both is considered protective from heart disease.)
In Dr. Jenkins's study, 24 healthy adults with mild to moderately high levels of LDL (above 4.1 mmol/L) ate a diet low in saturated fat for one month. For the next month, they ate the portfolio diet that included oats, barley, psyllium, eggplant, okra, soy, almonds and margarine enriched with plant sterols. (Plant sterols reduce the absorption of food cholesterol from the intestine and have been shown to lower LDL cholesterol by up to 15 per cent.)
While following the portfolio diet, half the group was instructed to replace 13 per cent of the calories from carbohydrate with a sunflower oil very high in monounsaturated fat. This was achieved by reducing bread and sugar and adding about one tablespoon of oil to breakfast, lunch and dinner.
After four weeks on the portfolio diet, HDL cholesterol increased by 12.5 per cent in the monounsaturated group; it didn't change in the group eating the low monounsaturated fat diet. Participants in both groups saw their LDL cholesterol fall dramatically, but even better results were achieved by those who added monounsaturated fat to their diet.
The take away message: Don't be afraid of healthy fat. Adding monounsaturated fat to a cholesterol-lowering diet can further reduce your risk for heart disease by boosting HDL cholesterol.
The following strategies can help raise good cholesterol in the bloodstream:
Increase monounsaturated fat
Excellent sources include olive oil, olives, canola oil, avocados, avocado oil, hazelnuts, macadamia nuts, almonds and almond oil.
Keep in mind that one tablespoon of oil delivers 120 calories and one avocado has roughly 320 calories. When adding monounsaturated fat, subtract a similar number of calories from your diet to prevent weight gain. Substitute this heart-healthy fat for refined starches, sweets and other less healthy foods.
Avoid trans fat
A steady intake of foods made with partly hydrogenated vegetable oil – a source of trans fat – can lower HDL cholesterol, not to mention increase bad cholesterol.
Trans fats can be found in many commercial bakery products, packaged snack foods, fried fast foods and certain margarines. Read nutrition labels – choose foods with zero grams of trans fat.
Yes, it's true that a daily drink raises HDL cholesterol. That goes for any type of alcoholic beverage, not only red wine.
That said, you need to weigh the potential benefits with the potential risks. A low to moderate intake of alcohol is linked with a higher risk of certain cancers, including breast cancer.
If you do drink, limit your intake to seven drinks a week (women) and nine a week (men).
Making time for aerobic exercise such as jogging, brisk walking, cycling and stair climbing can help you increase HDL cholesterol. Research suggests for the best results, duration is more important than intensity.
Aim to work out at least four times a week for 40 minutes a session. If necessary, slow your pace to increase the amount of time spent exercising.
Lose excess weight
Being overweight reduces HDL cholesterol and increases LDL cholesterol. Shedding weight can help to increase your HDL level, especially if you carry excess weight around your middle.
If you're a smoker, giving up tobacco will increase your HDL cholesterol level.
Leslie Beck, a Toronto-based dietitian at the Medcan Clinic, is on CTV's Canada AM every Wednesday. Her website is lesliebeck.com.