Aug. 5, 2021 -- Younger adults and postmenopausal women who ate more nutrient-rich "healthy" plant-based foods, and avoided unhealthy foods, had a lower risk of later heart disease, research shows.
These findings from two studies in two populations were posted online Wednesday in the Journal of the American Heart Association.
‘Portfolio Diet’ in Postmenopausal Women
While earlier research found that eating nutrient-dense plant-based foods helps lower blood cholesterol levels, it was not clear if this can also lower the risk of "hard" outcomes, such as heart attacks.
The findings are "very reassuring," David J.A. Jenkins, MD, co-author of the study in postmenopausal women, tells WebMD.
"We always say that cholesterol-lowering is a good thing. Here it's nice to see the proof," says Jenkins, a professor in the Departments of Nutritional Sciences and Medicine at the University of Toronto in Ontario, Canada.
Jenkins designed the "Portfolio Diet"-- rich in five types of cholesterol-lowering, nutrient-dense, plant-based foods -- in the early 2000s.
The new study showed that postmenopausal women whose eating pattern most closely followed the Portfolio Diet were 11% less likely to develop heart disease in the next 15 years than women whose diet was least aligned with this way of eating.
Senior study author John L. Sievenpiper, MD, says that in clinical practice, he tries to shift patients toward eating more of a plant-based diet.
For example, a patient could start by aiming to eat 45 grams of nuts or nut butters each day.
Each component "buys you about 5% to 10% cholesterol lowering," says Sievenpiper, who is an associate professor in the Department of Nutritional Sciences at the University of Toronto.
Lead author Andrea J. Glenn, a registered dietitian and a PhD candidate in nutritional studies, says that people can "start small by having oats for breakfast in the morning, adding some tofu to your dinner, and then increase as you get used to eating those foods."
A Priori Diet Quality Score (APDQS) in Young Adults
In a second study, 18- to 30-year-olds who had the highest A Priori Diet Quality Score (APDQS) -- meaning they frequently ate nutrient-dense plant-based foods -- were 52% less likely to have heart disease in middle age that those with the lowest scores.
"Quite a lot of our food supply is plant-based, but it tends to be highly processed and to have low-quality ingredients such as sugars or refined grains," says senior author David R. Jacobs Jr., PhD.
"What we are proposing is very similar to the U.S. dietary guideline" and the Mediterranean diet, but importantly, it emphasizes "nutritionally rich" plant foods, says Jacobs, a professor of public health in the Division of Epidemiology and Community Health at the University of Minnesota in Minneapolis.
The group developed the APDQS score in 2007.
"Our findings support the shift towards plant-centered diet patterns," Jacobs says, echoing the authors of the "Portfolio Diet."
"When you go to the grocery store and get your grocery bag, 70% of it should be nutritionally rich plant food, like broccoli and frozen peas," he advises.
"We really emphasize that it should not be a chore for people to eat this kind of diet; it should be the kind of diet that they would pick [for taste] and even for convenience."
Rather, "what we emphasize is the foods and putting those foods together to have a tasty and healthy meal -- that's our goal," says Jacobs.
The top 20% group of the APDQS are those who made nutritionally rich plant foods a central part of their diet, but they also ate some animal-based foods such as non-fried poultry and low-fat dairy products, he says.
"If, generally speaking, you are eating a lot of nutritionally rich plant foods, and if they are the center of your plate rather than meat, you can have some of the refined products" and sugar and salt to taste, he says. But “there's so much salt in everything that industry and restaurants prepare," you need to be careful.
People should make nutritious plant foods a central part of their diet, adding small amounts of lean meats, fish, seafood, and dairy products from time to time, he says.
"We discourage people from eating added sugar, sweet foods, soft drinks, and high-fat meats, especially, processed meats (e.g., ham, sausage, salami, etc.)," Jacobs says.
‘Plant-Based Eating Keeps People Well’
"The abundance of evidence, particularly in the last 5 to 10 years, really points to the fact that the best diet for human consumption is truly a minimally processed, low-fat, whole-food, plant-based diet,” says Andrew M. Freeman, MD, who was not involved in the research.
These are not really "diets," but rather they are "eating patterns" that are good for health, good for the environment, and associated with lower health care costs, notes Freeman, who is director of cardiovascular prevention and wellness at the National Jewish Health hospital in Denver.
Each study "reinforces in another subpopulation that this type of [plant-based eating] works, that it keeps people well," says Freeman, who is also co-chair of the Lifestyle and Nutrition Workgroup of the American College of Cardiology.
Clinicians are not trained in nutrition, "and therefore we don't always know the best way to apply it," but a nutrient-rich plant-based eating pattern "is incredibly powerful medicine," he says.
Freeman co-authored a study that found that 90% of close to 1,000 surveyed cardiologists received very little or no nutrition education during fellowship training.
"The message I got," Freeman says, was "if we change our diet, change our lifestyle early enough in life, we can potentially prevent and alter our health trajectories in such a significant way, why wouldn't you?"
Portfolio Diet in Women's Health Initiative Study
What is the Portfolio Diet?
You aim to eat more from five types of cholesterol-lowering foods:
- Nuts and nut butters: such as peanuts and peanut butter
- Plant proteins: such as soymilk, peas, chickpeas, and lentil soup
- Food with viscous fiber: such as oatmeal cereal, barley, eggplant, okra, apples, oranges, and berries
- Foods with phytosterols (found in plants): such as phytosterol-enriched margarine
- Monounsaturated fats: such olive or canola oil and avocados
And you aim to limit foods that are high in saturated fat and cholesterol:
What did the study in postmenopausal women show?
The study included more than 123,000 women who were 50 to 79 years old in 1993 to 1998 (average age 62) with no heart disease when they enrolled in the Women's Health Initiative study and replied to food frequency questionnaires.
The researchers calculated scores for how closely they followed the Portfolio Diet.
During 15 years of follow-up, compared to women who did not eat this way (bottom 25% of scores), those who did (top 25% of scores) were:
A Priori Diet Quality Score in the CARDIA Study
What is the APDQS score?
The score is based on points for frequency of eating 46 foods or beverages.
The 20 beneficial foods are:
- fruit, avocado, beans/legumes, green vegetables, yellow vegetables, tomatoes, other vegetables, nuts and seeds, soy products, whole grains, vegetable oil, fatty fish, lean fish, poultry, beer, wine, liquor, coffee, tea, and low-fat milk/cheese/yogurt. In practice, the amount of alcohol consumed was rarely more than a moderate level, the researchers note.
The 13 adverse foods are:
- fried potatoes, grain dessert, salty snacks, pastries, sweets, high-fat red meats, processed meats, organ meats, fried fish/poultry, sauces, soft drinks, whole-fat milk/cheese/yogurt, and butter.
The 13 neutral foods are:
- potatoes, refined grains, margarine, chocolate, meal replacements, pickled foods, sugar substitutes, lean meats, shellfish, eggs, soups, diet drinks, and fruit juices.
What did the study in young adults show?
The study by Yuni Choi, PhD, of the Department of Food Science and Nutrition at the University of Minnesota, and colleagues determined APQDS scores in participants in the Coronary Artery Risk Development in Young Adults (CARDIA) study.
The 4,946 participants were 18 to 30 years old in 1985-1986 when they enrolled in CARDIA.
During a 32-year follow-up, 289 participants developed heart disease.
The main findings were:
- Participants at the top 20% of APDQS scores had a 52% lower risk of developing heart disease than those at the bottom 20% of scores.
- Participants whose diet improved the most during the first 20 years of follow-up had a 61% lower risk of developing heart disease than those whose diet worsened the most.