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23 Side Effects of Eating Peanut Butter, According to Science

Is peanut butter good for you? We take a look at the science-backed evidence to look at the good and bad side effects of eating it.
FACT CHECKED BY Olivia Tarantino

There really is nothing quite like peanut butter. It's a popular pantry staple no matter how old you are as it's nutrient-dense, affordable, and convenient. While it's one of the most popular foods in America, you may wonder—is peanut butter good for you? After all, it is high in fat, contains about 200 calories per serving, and many people are allergic to it.

To be honest: the answer isn't black and white. There both benefits of peanut butter as well risks to regularly having this nut butter in your diet. (Yes, peanuts are technically a legume, but we all know it as nut butter.)

As far as peanut butter nutrition goes, jelly's partner-in-crime is high in healthy monounsaturated fats, micronutrient-rich (it's a good source of magnesium), and it's one of our favorite foods for weight loss.

Technically speaking, a 2-tablespoon serving of salted peanut butter contains 190 calories, 16 grams of fat (8.5 grams are monounsaturated, 4 grams are polyunsaturated, and 3.5 grams are saturated), 7 grams of carbs, 1.5 grams of fiber, 3 grams of naturally-occurring sugar, and 7 grams of protein.

So how exactly does this nut butter promote a flat belly, and what else does peanut butter do to your body? We went straight to the experts, and some of these science-baked side effects may surprise you.

Here are the health benefits of including peanut butter in your diet, as well as some of the negative effects. And if you're headed to the grocery store soon, get our guide to The 20 Top Peanut Butters—Ranked!

The Health Benefits of Peanut Butter


You'll feel fuller.

smooth creamy peanut butter in jar

Is peanut butter good for you? Ilyse Schapiro, MS, RD, CDN thinks so. She shares that peanut butter's monounsaturated fat and protein are highly satiating.

How to eat peanut butter for weight loss:

  • Have peanut butter on toast for breakfast with bananas and chia seeds
  • Add peanut butter to a sandwich for lunch with crushed whole raspberries
  • Pair peanut butter with an apple for a snack that can prevent you from overeating

"But always consume it in moderation," Schapiro adds. A good serving size is two tablespoons. You can also creatively work peanut butter into your meals.


You'll get an energy boost.

happy woman after a workout

"The protein, fiber, and healthy fat in peanut butter can give you that kick you need to start the day or as a pick-me-up midday," says Schapiro. "It also helps to keep blood sugar stable, which prevents those crashes later on." Start your day off right with this healthy breakfast staple to ward off afternoon cravings.


Peanut butter may help you lose weight.

Female leg stepping on floor scales

Even when you're on a calorie-restricted diet, studies have shown that including legumes can help with weight loss. Why? For starters, peanuts contain a good amount of protein—7 grams in 2 tablespoons. Add that to the high healthy fat and fiber content, and you've got a tasty snack that will keep you fuller longer. The result may be less caloric intake later in the day. "Most people find eating 200 calories of peanut butter is more satiating than, say, 200 calories of pretzels," says registered dietitian Jennifer McDaniel, MS, RDN, CSSD, LD. According to a study in the International Journal of Obesity, peanuts can even increase your metabolic furnace. In that study, subjects' metabolic rate jumped by 11% when they ate about 500 calories of peanuts daily for 19 weeks.


You'll have healthier muscles and nerves.

Woman with strong muscle arms doing push ups for exercise

Magnesium is an essential mineral that powers more than 300 biochemical reactions in the body. The nutrient has been shown to help fight headaches, muscle cramps, and fatigue. Peanut butter is a good source of magnesium, containing about 15% of your RDA in one two-tablespoon serving. That means PB can assist in body-temperature regulation, detoxification, energy production, the formation of strong bones and teeth, and maintenance of a healthy nervous system.


Fats in peanut butter may improve brain health.

Man working on crossword puzzle

According to McDaniel, studies have found that the monounsaturated fats found in foods like nuts and olive oil are protective of brain health and function. How? Nuts' antioxidative and anti-inflammatory properties help reduce stress (or oxidative damage) to the brain.


You may decrease levels of stress hormones.

happy woman laughing

"Eating peanut butter may help you fight the effects of stress," says registered dietitian Miriam Jacobson RD, CDN of PB contains beta-sitosterol, a plant sterol. In studies involving endurance athletes, beta-sitosterol was shown to normalize high cortisol levels and bring them back into balance with other hormones during times of stress. Beta-sitosterol can also help improve immunity.


You may improve your skin health.

woman with good skin

Speaking of vitamin E, in addition to the healthy fats that help your body absorb fat-soluble vitamins, peanut butter also happens to be high in vitamin E. The spread contains 2.9 milligrams of vitamin E per two-tablespoon serving or 15 percent of your daily value. Vitamin E is important for preventing heart disease, cancer, eye disorders, and cognitive decline. Most notably, antioxidant vitamin E can help protect your skin from the damaging effects of free radicals from UV exposure. Moreover, the monounsaturated fats in peanut butter will help keep your skin supple and naturally radiant.

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You may reduce your heart disease risk.

Happy Woman Holding Heart Shaped Hands Near Eyes. Closeup Of Smiling Girl With Healthy Skin Showing Love Sign

Because peanuts are chock-full of heart-healthy monounsaturated fat, they're good for your heart as much as your waistline. A 2015 study in JAMA Internal Medicine found that consuming as little as 30 grams of peanuts or peanut butter every week can help decrease the risk of total mortality and death from cardiovascular disease.


You lower your death risk.

older mature happy couple at table eating drinking

According to a 2015 Vanderbilt University study, eating nuts every day is linked to a lower total death risk. What gives nuts the ability to deter the reaper? Their density of health-promoting and protective nutrients. "Nuts have a healthy fat profile—including mono- and polyunsaturated fats—are rich in antioxidants, contain nutrients like potassium that help maintain a healthy blood pressure, are rich in fiber, and contain heart-healthy plant phytosterols," says McDaniel. Monounsaturated and polyunsaturated fatty acids have been shown to decrease LDL cholesterol and triglyceride levels, lowering the risk of metabolic syndrome, heart disease, and type 2 diabetes. On the contrary, you should watch out for these 9 "Healthy" Habits That Are Shortening Your Life, According to Experts.


You could prevent a peanut allergy.

peanut butter jar

Eating PB during pregnancy may actually help lower the risk of your child having a peanut allergy, according to guidelines by the National Institute of Allergy and Infectious Diseases. "If you yourself don't have a peanut allergy, a scoop a day might keep a food allergy away!" says McDaniel. A JAMA Pediatrics study found that non-allergic mothers who ate peanuts or tree nuts five times a week or more were less likely to have a baby with a nut allergy. "Mothers don't need to avoid any of these allergic foods," adds Frank R. Greer, MD, professor of pediatrics at the University of Wisconsin. "If anything, they might be beneficial."


You'll combat toxins.

Woman touching face

Peanuts' mono- and polyunsaturated fats help fat-soluble vitamins like vitamin E be absorbed by the body. Vitamin E protects against toxins such as air pollution and soothes premenstrual syndrome. It also combats eye disorders such as cataracts and neurological diseases such as Alzheimer's disease and diabetes.


You'll reduce diabetes risk.


Eating peanut butter may help reduce the risk of developing diabetes. Jacobson cites a study published in the Journal of the American Medical Association, which found that consuming one ounce of nuts or a half-serving of peanut butter (about one tablespoon) at least five days a week can lower the risk of developing diabetes by over 20 percent.


You'll turn off your fat genes.

woman measuring inches around belly

Now you know that peanuts give you belly-slimming monounsaturated fats, tummy-filling fiber, and metabolism-boosting protein. But peanuts have a hidden weapon in their weight-loss utility belt: Genistein, a compound that acts directly on the genes for obesity, helping to turn them down and reduce your body's ability to store fat. (Beans and lentils have the same magic ingredient, albeit in a slightly less delicious form.)

Registered dietitian Gina Hassick, RD, LDN, CDE, NCC, and founder of Eat Well With Gina shares her top tips for purchasing healthy peanut butter:

  • When buying peanut butter, try to choose one that has peanuts as its only ingredient.
  • If you prefer to purchase one with some added oil or salt, be mindful of the ingredients used.
  • Choose one that uses a healthier oil, not one that uses a hydrogenated or partially hydrogenated oil.
  • Avoid peanut butters that are "light" or "low-fat". When there is less of one ingredient, there is often another ingredient added. Light and low-fat peanut butters almost always have added sugar in place of the fat that was eliminated.

Pregnant mothers can consume peanut butter for healthy development.

Black man holding belly of his pregnant wife making heart

Pregnant women will also appreciate that the salty-and-sweet spread also has 28 milligrams, or 7 percent of your DV of folate, a prenatal vitamin that has been shown to help prevent birth defects and promote growth and development of the fetus.


Eat peanut butter to aid in muscle recovery.


Potassium plays a key role in muscle health and recovery, and the good news is that peanut butter has a good amount of this important mineral. With 179 milligrams of potassium in each two-tablespoon serving of the nutty spread, it can also help with relieving muscle soreness and cramping.


You'll lower blood pressure.

Nurse taking a patients blood pressure

Potassium is not only essential for muscle contraction, but it also plays a key role in lowering blood pressure, according to the American Heart Association. In fact, potassium deficiencies are linked to cardiovascular disease, renal disease, osteoporosis, and type 2 diabetes. To ensure peanut butter is a good food to reduce blood pressure, make sure you opt for an unsalted version.


You'll sleep better.

woman sleeping on bed in bedroom

No need to count sheep! A two-tablespoon serving of peanut butter contains 74 milligrams of the amino acid tryptophan, which is the precursor to the sleep hormones serotonin and melatonin, making it the ideal nighttime snack to catch some zzzs. Plus, PB contains magnesium, which can help relax your muscles and prepare your body for sleep.


You'll aid bone health.

senior woman holding wrist with joint pain poor bone health

Vitamin K is another fat-soluble vitamin peanuts' healthy fats will help your body absorb. Vitamin K is essential for normal blood clotting and aids in the transport of calcium throughout the body, which is helpful for bone health.


Your skin will glow.

happy woman outside

The lutein in peanuts can help improve your skin's elastin, which is essential for keeping your skin looking firm and wrinkle-free. Moreover, the monounsaturated fats in peanut butter will help keep your skin supple and naturally radiant.


You'll be more productive.

Man in glasses working on laptop

Peanut butter's protein, fiber, and healthy fat profile will give you the kickstart you need to take on your day. It's not only great as part of your morning meal, but it also makes a great pick-me-up when that afternoon lull hits. Check out these 30 Foods for All-Day Energy.

Potassium is not only essential for muscle contraction, but it also plays a key role in lowering blood pressure. In fact, potassium deficiencies are linked to cardiovascular disease, renal disease, osteoporosis, and type 2 diabetes.

The Negative Effects of Peanut Butter


You could gain weight.

Man measuring waistline with measuring tape

"Many of the health benefits of peanut butter can be negated if they're only consumed with white bread or crackers and jelly or chocolate," says McDaniel. She adds that certain processed peanut butters contain unhealthy additives and too much salt. "Reduced-fat peanut butters often up the sugar," says McDaniel. "And avoid peanut butters that have artery-clogging hydrogenated oils in the ingredient list."

Schapiro often recommends nut butters for clients who are trying to gain weight because they're so calorically dense. "Just one tablespoon has about 100 calories, and if you're digging into a jar, it's not likely you'll stop at just a spoonful," she says. "Most peanut butters also contain added sugar for flavor. Combining sugar and fat creates a hormone symphony for fat storage."


You may be exposed to pesticides.

Bags boiled peanuts

Some farmers can go heavy on the pesticides and herbicide use is rampant in peanut production. According to the USDA, 94 percent of planted acres of peanuts are covered in herbicides. The problem is that peanuts have a very light shell, so the chemicals can easily leach in. Pesticide exposure has been linked to birth defects and impaired fertility in men. Your best bet? Choose an organic variety.


There is an extremely small chance you could consume mold.


Jacobs typically doesn't recommend peanut products because of their susceptibility to invasions by fungi and mold. Aflatoxin, a fungus common to peanut products, can cause developmental delays in children, and over time it can lead to a higher risk of liver cancer, according to the NIH.

However, there might not be much to worry about. Light roasting helps to protect peanuts against aflatoxin. To date, the NIH reports that there's never been an outbreak of human illness caused by aflatoxins in the United States, but outbreaks have occurred in some developing countries. NIH experts recommend staying vigilant by buying only major commercial brands of peanuts and peanut butters, and by "discarding nuts that look moldy, discolored, or shriveled." You can also choose different nut butters such as almond or cashew. For more on some negative side effects of PB, see Dangerous Side Effects of Eating Too Much Peanut Butter.