Nuts that Help (and Harm) the Heart

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Many of you reading this have considered adding nuts to your diet to take advantage of their health benefits. But are all nuts created equal?

On a family vacation to Hawaii I tasted cookies made with macadamia nut butter. I wondered, could something this rich-tasting be heart-healthy? The answer has to do with which type of fat nuts contain and in what amounts. The fat we eat come in saturated, polyunsaturated, and monounsaturated forms, and the amounts of each we consume can have a large impact on health.

The American Heart Association (AHA) has long advocated reducing the amount of saturated fat in our diet since this type of fat is linked to the development of cardiovascular disease. For many years we in the medical community saw conflicting results after lowering saturated fat intake.

Different types of fats

As it turns out, what we substitute the saturated fat with is critical to long-term health benefits. If we replace saturated fat with carbohydrates, we see no overall benefit, but if we substitute saturated fat with polyunsaturated and monounsaturated fat, we see a reduction in the risk of developing cardiovascular disease. And, polyunsaturated fat has a slight edge over monounsaturated in lowering that risk.

Because substituting more carbohydrates negates the health benefits of reducing dietary saturated fat, nuts enter in as a nutritional recommendation; adding them to your diet is a way to reduce saturated fat while not adding significant amounts of carbohydrates. In general, nuts are a popular choice for a healthy diet as they are a source of protein, fiber, and trace elements like copper, manganese, and selenium.

Then why do macadamias taste so rich and buttery? The answer is that saturated fat is the main type of fat found in that type of nut. Macadamias contain 3.4 grams of saturated fat per ounce. Compare this to butter which contains 14.6 grams per ounce, and you can begin to see where the rich taste comes from.

Because of this, adding large amounts of macadamias to your diet would not be considered a good choice if the goal is to reduce saturated fat in your diet. The same goes for brazil nuts, which are also relatively high in saturated fat.

Replacing bad fats

According to the AHA, the best type of fat to replace saturated fat in your diet is the polyunsaturated kind. For a rundown on different types of fat, see an online article from the American Heart Association.

While increasing both polyunsaturated and monounsaturated fat in the place of saturated fat has been shown to reduce cardiovascular disease risk, the weight of scientific evidence gives a slight edge to the polyunsaturated variety.

Nutritional sources of polyunsaturated fat, however, are relatively hard to come by. But it seems there is a nut for every type of fat, and for polyunsaturated fat content, walnuts are the clear winner. Walnuts contain 13.4 grams of polyunsaturated fat per ounce, more than twice than the next highest content found in pecans. Brazil nuts come in third in terms of polyunsaturated fat content, but also contain relatively high levels of saturated fat, so one has to keep that in mind if the overall goal is reduction of saturated fat intake. You wouldn’t try to make a healthy cigarette, would you?

But if you are like me and only see walnuts as a crunchy addition to cakes and cookies, you may ask, what non-dessert dishes use walnuts? They can be added to any green salad, of course, but also pair well with meats like pork and beef, fish (especially salmon) and also with mushrooms, apples, pears, and ginger.

But if walnuts are not for you regardless, there are many nuts which are good sources of monounsaturated fat, and some which are good sources of both monounsaturated and polyunsaturated fat like the pecan. The nuts which have the highest amounts of monounsaturated fats are hazelnuts, cashews, almonds, and pistachios. And I don’t mean to beat up on the macadamia, so in the spirit of full disclosure—it is also high in monounsaturated fat.

It also wouldn’t be fair to exclude the peanut. Although technically it is a legume, closer to a bean rather than a nut, peanuts are commonly thought of as nuts. They deserve an honorable mention. After all, a 2015 study from Harvard Medical School demonstrated that eating peanuts every day reduced the risk of dying from heart disease and those who had at an ounce of peanuts at least twice a week lived longer. Like the tree nuts listed above, peanuts are a low-carbohydrate source of protein and are low in saturated fat and have moderate levels of monounsaturated and polyunsaturated fat.

Final thoughts

Dietary advice with regards to preventing heart disease can be complex and full of conflicting information. My patients are often asking, “Can I drink coffee?” “Are eggs good for you?”

When it comes to nuts and heart health, my recommendations would be: avoid macadamia and brazil nuts, look for healthy ways to increase your intake of walnuts. If you don’t like walnuts, hazelnuts, pecans, almonds, and pistachios are all good choices if your goal is substituting healthier fats for saturated fats. And don’t forget the peanut.