Peanut butter is one of the world’s most popular spreads.

To many peanut butter lovers, it tastes delicious and the texture is simply amazing — especially the way it sticks to the roof of your mouth before it melts.

Of course, not everyone can enjoy peanuts. Some people are allergic to peanuts, and they can even be deadly for a small percentage of the population (1).

But is peanut butter unhealthy for the remaining 99% of people? Let’s find out.

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Peanut butter is a relatively unprocessed food. It’s basically just peanuts, often roasted, ground until they turn into a paste.

Yet this isn’t necessarily true for many commercial brands of peanut butter. These may contain various added ingredients, such as:

  • sugar
  • vegetable oils
  • trans fat

And eating too much added sugar and trans fat has been linked to various health conditions, such as heart disease (2, 3).

Rather than buying processed foods with several added ingredients, choose peanut butter with only peanuts and maybe a bit of salt as its ingredients.

Summary

Peanut butter is basically a paste made of peanuts. Many lower-quality products also contain added sugar and vegetable oils.

Peanut butter is a fairly balanced energy source that supplies all of the three major macronutrients. A 3.5-ounce (100-gram) portion of peanut butter contains (4):

  • Carbohydrates: 22 grams of carbs (14% of calories), 5 of which are fiber
  • Protein: 22.5 grams of protein (14% of calories), which is quite a lot compared with most other plant foods
  • Fat: 51 grams of fat, totaling about 72% of calories

Even though peanut butter is fairly protein rich, it’s low in the essential amino acid methionine.

Peanuts belong to the legume family, which also includes beans, peas, and lentils. Legume protein is much lower in methionine and cysteine compared with animal protein.

Methionine deficiency is usually associated with an overall protein deficiency or certain disease states. Methionine deficiency is extremely rare for people who are generally in good health.

On the other hand, low methionine intake has also been thought to have some health benefits. Studies have shown that it may extend the lifespan of rats and mice, but it’s unclear if it works the same way in humans (5, 6).

For other protein-rich plant foods, check out this article on the 17 best protein sources for vegans and vegetarians.

Summary

Peanut butter is comprised of about 25% protein, making it an excellent plant-based protein source. However, it is low in the essential amino acid methionine.

Pure peanut butter contains only 20% carbs, making it suitable for a low carb diet.

It also causes a very low rise in blood sugar, making it a good option for people with type 2 diabetes (7).

One large review of eight studies found that eating peanut butter regularly was linked to a lower risk of developing type 2 diabetes in the long term (8).

These benefits have been partly attributed to oleic acid, one of the main fats in peanuts. Antioxidants may also play a role (9, 10).

Summary

Peanuts are low in carbs and suitable for people with type 2 diabetes or those following a low carb diet.

Since peanut butter is very high in fat, a 3.5-ounce (100-gram) portion contains a hefty dose of 597 calories (4).

Despite their high calorie content, eating moderate amounts of pure peanut butter or whole peanuts is perfectly fine on a weight-loss diet (11).

And since peanut butter is rich in heart-healthy fats and is a good source of protein, it can be a good option for vegetarians or those following a plant-based diet to incorporate into their diet in moderation.

Half of the fat in peanut butter is made up of oleic acid, a healthy type of monounsaturated fat also found in high amounts in olive oil.

Oleic acid has been linked to several health benefits, such as improved insulin sensitivity (12).

Peanut butter also contains some linoleic acid, an essential omega-6 fatty acid abundant in most vegetable oils.

Some studies suggest that a high intake of omega-6 fatty acids, relative to omega-3, may increase inflammation and the risk of chronic disease (13).

However, not all scientists are convinced. Higher-quality studies show that linoleic acid does not raise the blood levels of inflammatory markers, casting doubt on this theory (14, 15).

Summary

Pure peanut butter is a good source of healthy fats. While some people have been worried about its omega-6 linoleic acid content, there is limited evidence to justify their concerns.

Peanut butter is fairly nutritious. A 3.5-ounce (100-gram) portion of peanut butter provides many vitamins and minerals (4):

  • Vitamin E: 60% of the daily value (DV)
  • Vitamin B3 (niacin): 84% of the DV
  • Vitamin B6: 29% of the DV
  • Folate: 18% of the DV
  • Magnesium: 37% of the DV
  • Copper: 56% of the DV
  • Manganese: 65% of the DV

It is also high in biotin and contains decent amounts of:

  • vitamin B5
  • iron
  • potassium
  • zinc
  • selenium

However, be aware that this is for a 3.5-ounce (100-gram) portion, which has a total of 597 calories. Calorie for calorie, peanut butter isn’t that nutritious compared with low calorie plant foods like spinach or broccoli.

Summary

Although peanut butter is high in many healthy vitamins and minerals, it also contains a substantial number of calories.

Like most real foods, peanut butter contains more than just the basic vitamins and minerals. It also contains plenty of other biologically active nutrients, which can have some health benefits.

Peanut butter is quite rich in antioxidants like p-coumaric acid, which may reduce arthritis in rats (16).

It also contains some resveratrol, which is associated with a lower risk of heart disease and other chronic diseases in animals (17, 18).

Resveratrol has many other potential benefits, although human evidence is still limited.

Summary

Peanut butter is rich in antioxidants, including p-coumarin and resveratrol. These plant compounds have been associated with various health benefits in animals.

Even though peanut butter is quite nutritious, unprocessed peanut butter may also contain substances that can be harmful, including aflatoxins (19).

This is because peanuts grow underground, where they can be colonized by a widespread mold called Aspergillus. This mold is a source of aflatoxins, which are considered harmful to health.

According to the National Cancer Institute, no outbreaks of illnesses associated with aflatoxins have been reported in the United States. However, there are some concerns about the long-term health effects of aflatoxins, particularly in developing countries (20).

In fact, some human studies conducted in developing countries have linked aflatoxin exposure to liver cancer, stunted growth in children, and delays in mental development (21, 22, 23, 24, 25).

Fortunately, the processing of peanuts into peanut butter can significantly reduce the amount of aflatoxins present in the final product (26).

Additionally, the United States Department of Agriculture (USDA) closely monitors the amounts of aflatoxins in foods and makes sure that they don’t go over recommended limits.

You can also minimize the risks associated with aflatoxin exposure by sticking to commercial brands of peanut butter or peanuts and by tossing out any nuts that appear moldy, shriveled, or discolored (20).

For more information on food molds, check out this article.

Summary

Unprocessed peanut butter may contain aflatoxins, which are compounds that have been associated with adverse effects on health in developing countries. Purchasing commercial brands of peanut butter and discarding moldy or discolored nuts can minimize the risk of side effects.

There are a lot of good things about peanut butter, but also a few negatives.

It’s fairly rich in nutrients and a decent protein source. It’s also loaded with fiber, vitamins, and minerals, although this doesn’t seem as significant when you consider the high calorie load.

It is perfectly fine to incorporate moderate amounts of peanut butter into a healthful diet. But the main problem with peanut butter is that it’s so incredibly hard to resist.

Moderate consumption of peanut butter is unlikely to have any major negative effects. It’s more important to steer clear of sugary soda, trans fats, and other highly processed foods, if possible.