Are Nuts Good For Your Heart?

Which Nuts Are Best?

Last week I shared an important study about the benefits of replacing some of the animal protein in your diet with plant protein from whole grains. In case you have forgotten, the study showed replacing just 15 grams of the animal protein in your diet with an equivalent amount of protein from whole grains significantly decreased the risk of premature death from cardiovascular disease, stroke, and from all causes.

This was an important study because whole grains have been maligned in recent years. Low carb diets, keto diets, paleo diets, and low-lectin diets all recommend cutting whole grains out of your diet. Dr. Strangelove and his friends have been telling us to avoid whole grains, and too many Americans have been doing just that.

The study I shared last week reminds us that whole grains are good for our hearts. They are a great source of antioxidants, B vitamins, minerals, and phytonutrients. More importantly, they contain a unique type of fiber called resistant starch that supports the growth of heart-healthy gut bacteria. There are a few other foods that are a good source of resistant starch, but they are also on Dr. Strangelove’s “naughty list” of foods to avoid.

Unfortunately, you might have come away from last week’s article thinking that other plant protein sources, like beans, legumes, nuts, and seeds, weren’t important for reducing your risk of heart disease. However, the fact that they didn’t reduce the risk of premature death from heart disease in that study was likely an artifact of the way the study was designed.

The study asked what happens when you change 15 grams of the protein in your diet from red meat protein to different kinds of plant protein. That question was easy to answer for grains because they are a major source of protein in the American diet. However, Americans don’t get enough protein from either beans and legumes or nuts and seeds to provide a statistically valid answer to that question.

To correct any misconceptions from last week’s article I thought it might be valuable to review a study (M Guasch-Ferré et al, Journal Of The American Journal Of Cardiology, 70: 2519-2532) from a few years ago that looked at the effect of nut consumption on the risk of heart disease.

How Was The Study Done?

This study started by combining the data from three major clinical trials:

The first Nurse’s Health Study, which ran from 1980 to 2012,

The second Nurse’s Health Study, which ran from 1991-2013, and

The Health Professional’s Follow-Up Study, which ran from 1986-2012.

These studies combined enrolled 169,310 women and 41,526 men and followed them for an average of 32 years. All the participants were free of heart disease and cancer at the time they were enrolled. The design of these studies was extraordinary.

A detailed food frequency questionnaire was administered every 4 years. This allowed the investigators to calculate cumulative averages of all dietary variables, including nuts. This assured that the effects of nut consumption and diet represented the participant’s average diet over the 32-year duration of the study, not just their diet when they entered the study.

Participants also filled out questionnaires that captured information on disease diagnosis, disease risk factors, medicines taken, weight, and lifestyle characteristics every 2 years with follow-up rates >90%. This allowed the investigators to measure the onset of heart disease for each participant during the study. More importantly, 32 years is long enough to measure the onset of diseases like heart disease, which requires decades to develop.

The primary endpoint of the study was “cardiovascular disease”, which the investigators defined as fatal and non-fatal heart attacks, fatal and non-fatal strokes, and deaths from all types of heart disease. During this study, 14,136 participants developed cardiovascular disease. This was a large enough number for a detailed statistical analysis of the data.

Secondary endpoints were heart disease (fatal and non-fatal heart attacks) and stroke (fatal and non-fatal strokes).

When the authors compared people who consumed 5 or more one ounce servings of nuts per week with people who never or almost never consumed nuts, they found that nut consumption decreased:

Cardiovascular disease by 14%.

Heart attacks by 20%.

Strokes by a non-significant 2%.

This part of the study merely confirms what other studies have shown. What makes this study unique is that it identifies the relative heart health benefits of different kinds of nuts.

Which Nuts Are Best?

Nuts are an excellent source of vitamins, minerals, phytonutrients, and fiber. But what makes them particularly heart healthy is the healthy fats they provide.

Peanuts (which are actually legumes rather than true nuts) are rich in monounsaturated fats.

Tree nuts in general are an excellent source of polyunsaturated fats.
Walnuts

Walnuts are particularly rich in omega-3 polyunsaturated fats.

When they looked at individual nuts:

Consuming a serving of peanuts (35 peanuts) 2 or more times per week decreased:

- Cardiovascular disease by 13%.

- Heart attacks by 15%.

- Stroke by 10%.

- Peanut butter had no effect on cardiovascular outcomes, probably because many commercial brands of peanut butter add saturated fats to reduce separation of the oil and make their product creamier.

Consuming a serving of tree nuts (12-15 nuts) 2 or more times per week decreased:

- Cardiovascular disease by 15%.

- Heart attacks by 23%.

Consuming a serving of walnuts (14 walnut halves) one or more times per week decreased:

- Cardiovascular disease by 19%.

- Heart attacks by 21%.

- Stroke by 17%.

In case you missed it, walnuts were the superstars of the nut family. One serving/week of walnuts was more effective than two or more servings/week of peanuts or other tree nuts at reducing the risk of heart attacks, stroke, and overall cardiovascular disease. This is probably because walnuts are a particularly good source of omega-3 fats.

[Professor’s note: I include a serving of walnuts with my breakfast every morning.]

The authors concluded: “Findings from 3 large prospective cohort studies indicate that frequent intake of nuts, tree nuts, peanuts, and walnuts was associated with a lower risk of cardiovascular disease, independently from other cardiovascular risk, lifestyle, and dietary factors. Our findings support recommendations of increasing the intake of a variety of nuts as part of healthy dietary patterns to reduce the risk of chronic diseases in the general population.”

What Does This Study Mean For You?

I have consistently shared the evidence that primarily plant-based diets are associated with the best long-term health outcomes, especially when we look at chronic diseases like heart disease, diabetes, and cancer.

I have also consistently shared the message that “We have 5 food groups for a reason”. All 5 food groups are part of a healthy diet.

Unfortunately, Dr. Strangelove and his friends have been telling us that whole grains are bad for us. We should eliminate them from our diet. And too many Americans have been following that advice. That’s why last week’s “Health Tips From the Professor” article reviewed the evidence for heart health benefits from whole grain consumption.

The situation with nuts and seeds is a little different. Most people recognize them as healthy. They just don’t eat enough of them. That’s why this week’s article emphasized the heart health benefits from nut consumption. Here is the take home message I hope you get from this article:

Two or more servings/week of peanuts or tree nuts significantly reduces your risk of heart attack, stroke, and other cardiovascular diseases.

Walnuts are the superstars of the nut family. One serving/week of walnuts (14 walnut halves) was more effective at reducing the risk of heart attack, stroke, and other cardiovascular diseases than two or more servings/week of the other nuts.

This study was based on unprocessed nuts. Nuts coated with salt, sugar, or chocolate probably don’t qualify as heart healthy.

Processed foods made from nuts also may not be heart healthy. For example, peanut butter had no effect at decreasing heart disease risk in this study.

Finally, in closing I want to revisit my statement that “We have 5 food groups for a reason”.

The studies I shared this week and last week show that whole grains and nuts are important components of a heart healthy diet. But it doesn’t stop there.

All plant food groups are part of a heart healthy diet. In previous issues of “Health Tips From the Professor” I have shared studies showing beans, fruits, and vegetables are all important components of a heart healthy diet.

I have also shared recent studies showing that adding small amounts of eggs and dairy may make a vegetarian diet more heart healthy.

Finally, I have shared a study showing that small amounts of red meat can be heart healthy in the context of a primarily plant-based diet such as the Mediterranean diet.

Of course, we are talking about whole food diets. If you include sodas and highly processed foods in the diet, all bets are off.

The Bottom Line

I have also consistently shared the message that “We have 5 food groups for a reason”. All 5 food groups are part of a healthy diet.

The situation with nuts and seeds is a little different. Most people recognize them as healthy. They just don’t eat enough of them. That’s why this week’s article emphasized the heart health benefits of nut consumption. Here is the take home message I hope you get from this article:

Two or more servings/week of peanuts or tree nuts significantly reduces your risk of heart attack, stroke, and other cardiovascular diseases.

Walnuts are the superstars of the nut family. One serving/week of walnuts (14 walnut halves) was more effective at reducing the risk of heart attack, stroke, and other cardiovascular diseases than two or more servings/week of the other nuts.

This study was based on unprocessed nuts. Nuts coated with salt, sugar, or chocolate probably don’t qualify as heart healthy.

Processed foods made from nuts also may not be heart healthy. For example, peanut butter had no effect at decreasing heart disease risk in this study.

Finally, in closing I want to revisit my statement that “We have 5 food groups for a reason”.

The studies I shared this week and last week show that whole grains and nuts are important components of a heart healthy diet. But it doesn’t stop there.

All plant food groups are part of a heart healthy diet. In previous issues of “Health Tips From the Professor” I have shared studies showing beans, fruits, and vegetables are all important components of a heart healthy diet.

I have also shared recent studies showing that adding small amounts of eggs and dairy may make a vegetarian diet more heart healthy.

Finally, I have shared a study showing that small amounts of red meat can be heart healthy in the context of a primarily plant-based diet such as the Mediterranean diet.

Of course, we are talking about whole food diets. If you include sodas and highly processed foods in the diet, all bets are off.

For more details, read the article above.

These statements have not been evaluated by the Food and Drug Administration. This information is not intended to diagnose, treat, cure, or prevent any disease.