Eat Your Way to Lower Cholesterol: The Portfolio Diet

When it comes to managing cholesterol, you’ve probably heard the usual advice:

“Limit your saturated and trans fats.”
“Cut back on alcohol.”
“Eat less sugar and refined carbs.”

What if there was an approach where you were asked to eat more, but still managed to lower your cholesterol? The Portfolio Diet purports to do just that.

The Portfolio Diet is a mostly vegetarian meal plan (eggs and meat are allowed, but less than three times per week) developed by a team of researchers led by Dr. David Jenkins at the University of Toronto.  The premise behind the diet is that by combining foods and nutrients known to have cholesterol-lowering effects – soy protein, viscous fibres, nuts and plant sterols – the resulting portfolio of foods creates a greater reduction in cholesterol.

The results are promising – subjects who were provided a strict, vegetarian Portfolio Diet for one month were able to lower their cholesterol by almost as much as subjects who were given lovastatin (a cholesterol medication) and a vegetarian diet low in saturated fat (29.6% vs. 33.3%).¹ After one year of allowing study participants to follow the Portfolio Diet on their own, the average reduction in cholesterol was about 13%.² The Portfolio Diet may also help to raise HDL (“good”) cholesterol levels and lower blood pressure.^2,3

The Portfolio Diet as it was created is actually quite difficult to follow: after one year, only 2 of 66 participants were able to maintain the strictest, vegan version of the diet, and 5 stayed vegetarian.² Still, almost ⅓ of the subjects were able to maintain their initial reduction of cholesterol of about 20%, and it was strongly correlated with whether they were able to stick to the diet.² In other words, this is not an invitation to throw out your medications, but you may see some changes by gradually incorporating the recommended foods below into your diet "portfolio":

Viscous (Soluble) Fibres

Why they work:
Unlike insoluble fibre, the type of fibre that keeps us “regular”, viscous fibre forms a “gel” and slows the movement of food in our digestive tract. It helps to reduce our cholesterol by binding with bile that is secreted in our gut and carrying it out of our bodies instead of allowing it to be reabsorbed by our intestines. Our livers must then use the cholesterol in our blood to produce more bile, thereby lowering our cholesterol.

Where to find them:
In the studies, subjects got their viscous fibre from oats, barley, psyllium, okra and eggplant. Other rich sources include beans, prunes, pears and citrus fruit.

How much you should eat:
Study participants ate about 15-20 g per day, but you may see some cholesterol-lowering effects with as little as 5 g per day, the same amount that is in a tablespoon of ground psyllium. A ¾ cup serving of beans provides about 3 g, while ½ cup of oats or barley provides about 1 g.

Soy Proteins

Why they work:
Choosing soy/plant proteins over animal proteins helps to reduce the saturated fat and cholesterol in our diet while increasing the viscous fibre we eat. Soy proteins themselves appear to lower cholesterol by decreasing the liver’s production of cholesterol and by increasing its uptake of LDL cholesterol. Soy also contains compounds called isoflavones, which have heart-healthy antioxidative effects and may also help to lower cholesterol.

Where to find them:
Soy milk and tofu are excellent, convenient choices. Subjects were also given soy burgers and soy hot dogs, but those tend to be heavily processed and high in sodium. Instead, try other traditional Asian soy foods, like tempeh, edamame, miso or natto. Soya sauce is not rich in soy proteins and thus will not help to reduce your cholesterol.

How much you should eat:
Aim for 25-40 g of soy protein per day. ¾ cup of tofu, edamame (boiled green soybeans) or tempeh contains about 20 g of soy protein, while a cup of soy milk has about 7 g.

Plant Sterols

Why they work:
Plant sterols are compounds found in plant cell membranes that are structurally similar to cholesterol. Because of this, plant sterols can partially block the absorption of dietary cholesterol in the gut.

Where to find them:
Although plant sterols naturally occur in vegetable oils and other plant foods that we eat, they are only available in small amounts, so the best way to get enough is actually through supplementation. While fortified spreads (i.e. margarine) and beverages (orange juice, soy milk) can be readily found in the States, Canada only approved the sale of foods fortified with plant sterols last spring, so expect them to slowly appear on store shelves over the next few years.

How much you should eat:
Read the labels of your supplements or fortified foods to help you figure out how much you need to take/eat to get 2 g of plant sterols per day.

Nuts

Why they work:
Nuts combine many components of the Portfolio Diet into one convenient package – they are a source of plant protein, viscous fibre, plant sterols and monounsaturated fats.

Where to find them:
Study participants ate almonds (partly because the research was sponsored by the Almond Board of California), which actually have the highest fibre content of all nuts and are fairly high in monounsaturated fats. Other nuts high in monounsaturated fats include macadamias, hazelnuts, pecans and pistachios. Walnuts are unique because they are the only nut with a significant amount of omega-3 fatty acids (about 14% of its total fat content, vs. about 1% for most nuts).

How much you should eat:
2-4 tablespoons per day, which is equal to ½-1 serving in Canada’s Food Guide.

Monounsaturated Fats

Why they work:
Not originally a part of the Portfolio Diet, in December 2010, Drs. Jenkins, Kendall and their team of researchers published a study in the Canadian Medical Association Journal (CMAJ) to study the effects of adding monounsaturated fats to their dietary portfolio.⁴ Previous studies have found that replacing saturated and trans fats with monounsaturated fats have helped to lower LDL cholesterol, and that monounsaturated fats act as antioxidants in the body. In the CMAJ study, the researchers focused on replacing carbohydrates in the diet with monounsaturated fats and found that it helped to increase HDL cholesterol without reducing the overall effects of the Portfolio Diet.

Where to find them:
Jenkins and Kendall used sunflower oil and avocado in their study. Other oils that are high in monounsaturated fat include safflower oil, canola oil and olive oil. As mentioned previously, many types of nuts are also high in monounsaturated fat. 

How much you should eat:
Instead of focusing on adding monounsaturated fats to your diet, try to replace saturated fats and carbohydrates with them. For example:

• Cook with oil or non-hydrogenated margarine instead of butter
• Use olive oil and vinegar to make a vinaigrette instead of using a creamy dressing on your salads
• Snack on nuts instead of crackers
• Slice up avocado and use it as a sandwich filling or in your salads