All plant foods are not created equal when it comes to your heart

In last week’s post, I wrote about the dangers of saturated fat for heart health… including for vegans who have enthusiastically embraced the coconut oil craze! The article I referenced in that post – ‘Dietary Fats and Cardiovascular Disease: A Presidential Advisory From the American Heart Association’ – cautioned that replacing saturated fat with refined carbohydrates and sugars did not reduce deaths from cardiovascular causes such as heart attacks and strokes. (No good news for lovers of vegan cupcakes there.)

Now a new study on plant-based diets and heart disease sheds more light on which carbohydrate foods to eat, and which to avoid, if you’d like to show your heart some love.

The study included over 166 000 women enrolled in the long-running Nurses’ Health Study, which has been tracking the diets, lifestyle habits and health outcomes of female nurses in the US since 1984, and over 43 000 men enrolled in the counterpart study for males, the Health Professionals Follow-up Study. All participants were free of chronic diseases at the time the study began.

Ever since they were enrolled in the studies, participants have been filling out food-frequency questionnaires every 2-4 years. The researchers created 3 separate indexes from these questionnaire data:

  1. An overall plant-based diet index (PDI), which simply assigned positive scores to foods derived from plants, and negative scores to foods of animal origin.
  2. A healthful plant-based diet index (hPDI), which scored whole grains, fruits, vegetables, nuts, legumes, oils, tea and coffee positively, and juices, sugar-sweetened beverages, refined grains, potatoes and fries, sweets and animal foods negatively.
  3. An unhealthful plant-based diet index (uPDI), which gave positive scores to less-healthy plant foods and negative scores to animal and healthy plant foods.

Here are some examples of how the researchers categorised various plant-derived foods:

So what did they find? Those with a higher PDI – that is, people who generally ate more plants and less animals – had a slightly decreased risk of coronary heart disease (which they defined as non-fatal heart attack, and fatal coronary heart disease), which failed to reach statistical significance, meaning that the observed association between heart disease and a more plant-based diet could have been due to the random play of chance.

But those with the highest hPDI – in other words, people who were eating the healthy plant-based foods – had a 25% lower risk of heart disease, which was highly statistically significant (p <0.001, for the numbers nerds, meaning there is less than a one in a thousand chance that this was a random finding rather than a genuine association).

And conversely, those with the highest uPDI – people eating the most unhealthy, refined plant foods – had a 32% higher risk of coronary heart disease, again at p <0.001.

It’s important to note that this was not by any means a study of vegans or vegetarians; animal food intake ranged from 5-6 servings per day in the highest consumers to 3 to 4 servings per day in the lowest.

However, within this group of very carnivorous medical and health care professionals, the researchers found that “even a slightly lower intake of animal foods combined with higher intake of healthy plant foods is associated with lower CHD risk” whereas there was “a potentially stronger association for less healthy plant foods” with CHD risk than with animal foods.

That’s a sobering thought for junk food vegans who think that merely cutting animal products out of their diet will protect them against the leading underlying cause of death in Australia.

Why? Here’s what the researchers thought:

“greater adherence to hPDI would lead to diets high in dietary fiber, antioxidants, unsaturated fat, and micronutrient content, and low in saturated fat and heme iron content… all of which could aid in weight loss/maintenance, enhance glycemic control and insulin regulation, improve lipid profile, reduce blood pressure, improve vascular health, decrease inflammation, and foster more favorable diet-gut microbiome interactions (e.g., through lowered levels of trimethylamine N-oxide), thereby lowering CHD risk. Greater adherence to uPDI, on the other hand, leads to diets with higher glycemic load and index; added sugar; and lower levels of dietary fiber, unsaturated fats, micronutrients, and antioxidants, which could result in higher CHD risk through the above-mentioned pathways.”

Now personally, I dispute lumping the humble potato in with unhealthy plant foods, and including vegetables oils in with the healthy ones. The only two dietary interventions which have been shown to reverse coronary artery disease – the Ornish and Esselstyn programs – specifically include potatoes and exclude vegetable oils.

But overall, this study provides good guidance on how to eat to keep your heart healthy. Fill your plate with fruits, vegetables, whole grains and legumes; include  nuts and seeds in moderate quantities (unless you tend to gain weight easily, in which case you’re better off steering clear of them aside from a modicum of omega 3-rich seeds each day); and keep the vegan doughnuts, chocolate, cupcakes, fruit juice and other low-value food to a very occasional treat… or better still, cut the vegan junk food out altogether and learn to make treats from wholesome plant foods.

Does the thought of giving up vegan junk food make you panicky? Don’t know how to make whole plant foods taste good? I’ve got you covered :). My EmpowerEd health and nutrition education program is packed with resources on how to implement this way of eating, including video recordings of my full-day Empowered Eating seminar and Plant-Powered Oil-Free Cooking workshop; Healthy Eating 101 which covers kitchen set-up, meal planning and batch cooking; and 2 live webinars per month – an open Q&A session and an in-depth exploration of an important health topic. Your first month of membership is 100% free. Register here and get EmpowerEd to live your best life!

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