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

It tastes delicious, the texture is simply amazing and the way it sticks to the roof of your mouth before it melts is wonderful. At least that’s how many connoisseurs would describe it.

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

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

Peanut butter is a relatively unprocessed food.

It's basically just peanuts, often roasted, that are ground until they turn into a paste.

However, this doesn’t apply to many commercial brands of peanut butter that contain various added ingredients, such as sugar, vegetable oils and even trans fat.

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

Rather than buying junk food, choose real peanut butter. It should contain nothing but peanuts and maybe a bit of salt.

For all purposes, the health effects of regular peanuts should be almost identical to those of peanut butter since it’s essentially just ground peanuts.

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 macronutrients. A 100g portion of peanut butter contains (4):

  • Carbohydrate: 20 grams of carbs (13% of calories), 6 of which are fiber.
  • Protein: 25 grams of protein (15% of calories), which is quite a lot compared to most other plant foods.
  • Fat: 50 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 to animal protein.

For those who rely on peanut butter or beans as their main protein source, methionine insufficiency is a real risk.

On the other hand, low methionine intake has also been hypothesized 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 and is a perfect option for people with type 2 diabetes (7).

One observational study showed that women who ate peanut butter 5 times per week or more were at a 21% reduced risk of type 2 diabetes (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 100-gram portion contains a hefty dose of 588 calories.

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

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 (9).

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 (12).

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 (13, 14).

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

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

  • Vitamin E: 45% of the RDA
  • Vitamin B3 (Niacin): 67% of the RDA
  • Vitamin B6: 27% of the RDA
  • Folate: 18% of the RDA
  • Magnesium: 39% of the RDA
  • Copper: 24% of the RDA
  • Manganese: 73% of the RDA

It is also high in biotin and contains decent amounts of vitamin B5, iron, potassium, zinc and selenium.

However, be aware that this is for a 100-gram portion, which has a total of 588 calories. Calorie for calorie, peanut butter isn't that nutritious compared to 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 amount 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 (15).

It also contains some resveratrol, which is associated with a lower risk of heart disease and other chronic diseases in animals (16, 17).

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 linked to various health benefits in animals.

Even though peanut butter is quite nutritious, it may also contain substances that can be harmful.

At the top of the list are the so-called aflatoxins (18).

Peanuts grow underground, where they tend to be colonized by a ubiquitous mold called Aspergillus. This mold is a source of aflatoxins, which are highly carcinogenic.

While humans are fairly resistant to the short-term effects of aflatoxins, what happens down the line is not fully known at this point.

Some human studies have linked aflatoxin exposure to liver cancer, stunted growth in children and mental retardation (19, 20, 21, 22).

But there is some good news. According to one source, the processing of peanuts into peanut butter reduces the levels of aflatoxins by 89% (23).

Additionally, the USDA monitors the amounts of aflatoxins in foods and makes sure that they don't go over recommended limits.

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

Summary Peanut butter may contain varying levels of aflatoxins, which are toxic compounds formed by a type of mold. They have been associated with an increased risk of liver cancer.

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.

On the other hand, it’s a potential source of aflatoxins, which are associated with harmful effects in the long run.

Even though you shouldn't use peanut butter as a dominant food source in your diet, it’s probably fine to eat every now and then in small amounts.

But the main problem with peanut butter is that it's so incredibly hard to resist.

If you eat only small amounts at a time, it probably won't cause any harm. However, it can be almost impossible to stop after eating just a spoon full.

So if you have a tendency to binge on peanut butter, it may be best to avoid it altogether. If you can keep it moderate, by all means, continue to enjoy peanut butter every now and then.

Moderate consumption of peanut butter is unlikely to have any major negative effects as long as you are avoiding truly awful foods like sugary soda, trans fats and other highly processed junk foods.