Dr. David Jenkins, a professor of nutritional sciences at the University of Toronto, likens healthy eating to smart financial investing.
When you build an investment portfolio, “you’re spreading out your risks and benefits and trying to maximize your financial returns,” he said.
That’s the philosophy behind the portfolio diet, which Dr. Jenkins developed in the early 2000s after realizing that eating many different foods with cholesterol-lowering properties could lead to big heart benefits. These foods include legumes, nuts, extra virgin olive oil, fruits and vegetables.
The returns can be impressive: Some studies suggest that following the diet could lower levels of LDL, or “bad” cholesterol, by around 30 percent; and reduce the risks of coronary heart disease and stroke.
What is the portfolio diet?
Similar to the heart-healthy Mediterranean diet, the portfolio diet emphasizes fiber, healthy fats and plant sources of protein. Nuts and seeds, legumes (especially products made from soy beans such as tofu, tempeh and soy milk) and rich sources of monounsaturated fats (like extra virgin olive oil, canola oil and avocados) are key elements of the diet.
The portfolio diet also prioritizes foods that are high in a type of fiber called viscous fiber, which is found in certain plant foods like oats, barley, okra, eggplant and chia seeds, and fiber supplements like psyllium. Viscous fiber turns into a gel-like substance in your intestines, where it binds to cholesterol to reduce its absorption, said Andrea Glenn, an assistant professor of nutrition at New York University.
A group of naturally occurring plant compounds called phytosterols (or plant sterols) are also key components of the portfolio diet. Because these compounds have a similar structure to cholesterol, they compete with it for absorption, helping your body absorb less cholesterol, said Penny Kris-Etherton, a professor emerita of nutrition at Pennsylvania State University. Phytosterols are found in all plant foods, including nuts, fruits, vegetables, vegetable oils and whole grains like wheat germ and rice bran.
The portfolio diet discourages the consumption of animal products that are high in saturated fats, such as butter and red and processed meats. Consuming too many saturated fats can raise blood levels of LDL, which can increase your risk of high blood pressure, heart attack and stroke. Monounsaturated fats, on the other hand, help to lower LDL.
What does the research suggest?
In 2003, Dr. Jenkins and his team published the results of a small trial — one of the first to test the portfolio diet — which found that it lowered cholesterol nearly as well as statins.
The researchers split 46 adults with high cholesterol into three groups: One that followed a diet very low in saturated fats, another that followed a diet very low in saturated fats and also took a statin, and a third that followed the portfolio diet. After one month, the portfolio diet group reduced their blood LDL levels by about 29 percent — nearly as much as the statin group’s 31 percent. The low-saturated fat group reduced their LDL levels by just 8 percent.
The findings were encouraging, Dr. Jenkins said, but the study did not last long enough to show the diet’s potential long-term benefits. And because the study only included people with high cholesterol, it couldn’t demonstrate whether the pattern would benefit larger groups of people.
Over the following decades, additional research on the portfolio diet echoed Dr. Jenkins’ findings on the diet’s potential to lower cholesterol, but most studies only followed participants for short periods.
Then, in 2023, Dr. Glenn and her colleagues published a larger, longer study on about 210,000 nurses and other health professionals who didn’t have cardiovascular disease. After analyzing how they ate over up to 30 years, Dr. Glenn and her team found that those who followed the portfolio diet most closely had a 14 percent lower risk of developing cardiovascular disease (including coronary heart disease and stroke) than those who followed the diet the least closely.
Because the study only found associations between the portfolio diet and lower cardiovascular risks, it could not prove that the diet directly reduced them. And the study relied on people to self-report what they ate, which isn’t always accurate. But the study’s size and length made a strong case for its benefits.
Is the portfolio diet easy to follow?
The portfolio diet has daily target recommendations for its featured nutrients: 50 grams of plant proteins, 45 grams (by weight) of nuts and seeds, 45 grams (by weight) of cooking oils (or other foods like avocados) that are high in monounsaturated fats, 20 grams of viscous fiber and two grams of plant sterols. But you don’t need to meticulously track and weigh your food to get the diet’s cholesterol-lowering benefits.
Even incorporating a few of its key nutrients will help, Dr. Glenn said. For instance, half of an avocado would satisfy the fat target. And a half-cup of cooked broccoli with a medium sweet potato and a half-cup of brown rice would provide up to 40 percent of the fiber goal.
That said, it can be challenging to meet the diet’s phytosterols recommendation, said Hyunju Kim, an assistant professor of epidemiology at the University of Washington. A typical Western diet contains only about 15 percent of the recommended amount. Many people find that phytosterol supplements can help them reach this goal, Dr. Glenn said. Though keep in mind that there is not much research comparing the cholesterol-lowering effects of phytosterol supplements with whole foods, and most experts recommend that people get nutrients from food rather than from supplements. People shouldn’t use phytosterol supplements as substitutes for plant-based foods, Dr. Jenkins said.
The portfolio diet’s relative flexibility is part of what makes it sustainable, Dr. Kris-Etherton said. Contrast that with other diets that may be more restrictive, such as the keto and paleo diets.
The more heart-healthy, plant-based foods you can eat, the less room you’ll have in your “portfolio” for foods that increase your cholesterol — such as those high in saturated fats, Dr. Jenkins said.
Caroline Hopkins Legaspi is a Times reporter focusing on nutrition and sleep.
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