3 Reasons to Avoid Peanuts… and How to Make Them Less Harmful if You Can’t

The purpose of this website is not to scare you away from your favorite foods.  The purpose of this website is to share information.  Recommendations about what to eat and what to avoid can be misleading, even when they come from really smart people with important-sounding job titles and lots of letters after their names.  The folks making those recommendations often leave out important pieces of information, either intentionally in the case of marketers or unknowingly and due to ignorance and laziness.  But you can only make an informed decision about what to eat if you have a complete or mostly complete picture of what you’re actually putting in your body when you consume certain foods.

If you saw the title of this blog post and thought to yourself, “Great, another food I can’t eat,” then PLEASE, keep reading! This was written with you in mind.  I understand the confusion and frustration when you see foods labeled good and bad and sometimes in contradiction, depending on the source.  Food is complicated.  Food can be both good and bad. Sometimes you decide that the bad outweighs the good. It helps to have a set of criteria.

I apply a “three strikes law” when determining whether to include a food in my diet, even on a semi-regular basis.  If I come upon three or more solid, convincing, evidence-based reasons why a food can do me harm, I’m not putting it in my body. Bottom line.  And that’s especially true if I can obtain the same nutrients from some other food with perhaps two, just one, or ideally zero strikes. Yes, I’m a weirdo – taste is secondary in my book.

When you start learning about nutrition, you realize early on that there’s no perfect food. Cruciferous vegetables like broccoli are potent cancer-fighters but they are also goitrogenic and can inhibit thyroid function. Eggs are packed with nutrients but the whites can irritate and inflame the gut, especially in those with autoimmune issues. Dark chocolate is all the rage these days but many cocoa products contain worrisome levels of cadmium, a known carcinogen. And even spinach consumption can pose at least a theoretical risk of kidney stone formation due to its oxalate content.

For each of these foods there are strategies for mitigating some of the potential harm: you can cook your broccoli and spinach, eat only the yolks and discard the white part of the egg, and avoid chocolate products that have tested high for cadmium.  But you can’t always eliminate – or even minimize – the toxic compounds in certain foods. Even if you make the effort it’s difficult, if not impossible, to be sure you were successful. This is where quantity and frequency come into play. Yes, spinach and broccoli might cause problems but not in the amounts that most of us are eating them.

Healthy? Or nutritious? Or both?

When deciding what to eat for disease prevention, I think it’s important to draw a distinction between those foods that are “nutritious” and ones labeled “healthy.” They aren’t necessarily one in the same and the terms shouldn’t be used interchangeably.

By definition, a nutritious food is one that contains nutrients, as most foods do.  These vitamins and minerals often include some of those essential to our survival. They may be present in an amount that will prevent a deficiency and this is the amount that often appears as the recommended intake advised by government and health organizations.  It’s basically the bare minimum. Enough to stave off scurvy in the case of vitamin C or rickets if we’re talking about vitamin D.  The nutrient content is often not the amount needed for optimal health, which is why a varied diet and supplements are needed.

A “healthy” designation, on the other hand, suggests that a food is both safe to eat in the amounts and frequency that most people tend to consume it and that it supports rather than detracts from good health.  At least that’s the way I see it.

Peanuts are a great example of a food that, while nutritious, cannot be considered healthy the way they appear in the diet of the average person who chooses to eat them at all. Peanuts may be a decent source of some of the B vitamins, as well as magnesium and resveratrol. But the amounts are relatively modest and you’d be better off getting those from other foods or in supplement form.

When I first went low-carb, peanuts quickly became my best friend.  They provided a satisfying, portable, and convenient on-the-go snack option that I deemed healthy by virtue of the fact that they are neither a grain nor a starch.  As such, they help keep blood sugar and cravings in check and I considered them a physique-friendly alternative to chips and crackers when hankering for some crunch.

The problem is that peanuts are way too easy to over-consume.  Peanut butter even more so. Most people I know who consume peanuts or peanut butter are doing so on a regular basis, as in daily or several times a week, for years and years.  That constitutes chronic ingestion and with chronic ingestion comes long-term accumulation, but of what exactly? That’s what concerned me about peanuts from a health standpoint and I decided to do some research. What I discovered came as a surprise, considering that peanut butter has been a childhood staple and default sandwich filling for generations of Americans.  I couldn’t really recall ever hearing anything negative about it except for an occasional salmonella outbreak.

The original recommendation by health experts to include peanuts in our diets was likely based on the fact that peanuts, like all plant foods, are cholesterol-free. That certainly would have resonated in 1985 and may still if you ignorantly cling to the cholesterol myth.  Informed eaters know not to blindly accept the advice dished out by nutrition experts, especially given their proven ties to industry and the bias and conflicts of interest that run rampant in this realm.

These days peanuts are promoted as being “heart healthy,” due to their monounsaturated fat content. You can get that same benefit – via oleic acid – from olive oil, avocado, or actual nuts (peanuts are legumes). Informed eaters know not to evaluate a food based on an isolated nutrient – no matter how beneficial – but to consider the whole “package.”

There’s a glaring weakness in the way nutrition science is both taught and practiced in this country: the rush to anoint a food “healthy” based – often exclusively – on the presence (or lack) of a single compound currently accepted as either beneficial or harmful…  and the public’s willingness to accept such recommendations as the end of the story. There’s an unwillingness to make a case for or against putting something in our bodies because we’re too lazy to dig deeper or too arrogant to think we need to.

I wish it weren’t so, but the case against peanuts is just too strong and if I were a prosecuting attorney I’d consider it a slam dunk.  To me, peanuts are just more trouble than they’re worthThey’re one of the most allergenic and pesticide-contaminated foods on the planet, for starters, but here are the three biggest reasons peanuts are NOT healthy and why I gave them up nearly a decade ago – even before I adopted the paleo lifestyle and a complete banishment of legumes. The next time someone tells you that peanuts are healthy, ask them if they’re familiar with omega-6 fatty acids, lectins, and aflatoxin and the effects each has in the body.

1. Omega-6 fatty acids

Peanuts are loaded with omega-6 fatty acids, which distorts the omega-6 to omega-3 ratio. Your body needs only small amounts of omega-6 fatty acids but the average American takes in far too many, mostly in the form of refined, industrial seed oils and processed foods. While omega-3’s help to reduce triglyceride levels, lower blood pressure, and prevent irregular heartbeats, excess omega-6 fats promote inflammation, increasing the risk for cancer and heart disease.

The ratio of omega-6 to omega-3 fatty acids in a typical American diet today is thought to be 16 to 1 but we evolved on diets with a ratio of approximately 1 to 1.

According to the Center for Genetics, Nutrition and Health study:

“Excessive amounts of omega-6 polyunsaturated fatty acids (PUFA) and a very high omega-6/omega-3 ratio, as is found in today’s Western diets, promote the pathogenesis of many diseases, including cardiovascular disease, cancer, and inflammatory and autoimmune diseases, whereas increased levels of omega-3 PUFA (a low omega-6/omega-3 ratio) exert suppressive effects.

Additionally, too many omega-6 fats can lead to asthma, arthritis, diabetes, obesity, irritable bowel syndrome, and macular degeneration. Peanuts contain 5,000 times more omega-6 than omega-3.

2. Lectins

Lectins are a type of protein that bind to cell membranes.  Some lectins, like those found in tomatoes and raspberries, are thought to be health-promoting.  Many types of lectins, however, cause negative reactions in the body, including damage to the intestinal lining. When enough of these lectins are consumed, it can trigger the body to evacuate GI contents. This leads to vomiting, cramping, and diarrhea.

Lectins are very difficult to digest. When they stick to our cells they can trigger an immune response and inflammation.  Research has implicated lectins in several inflammatory conditions, including rheumatoid arthritis.  Additionally, lectins seem to mimic the behavior of insulin, making it harder to manage one’s weight.

Peanuts contain a lectin that increases rates of cell-division – definitely not something that’s desirable when the cell in question is a cancer cell!

In vitro studies have shown the following with regard to peanut lectins:

  • In isolated human colon cancer cells, peanut lectin is a mitogen, or growth-promoter.
  • A peanut lectin – agglutinin – causes colon cancer cells to proliferate through a process called altered glycosylation.
  • Altered glycosylation may cause inflammatory bowel disease-related cancers.

To be fair, these are lab studies and the harmful effects are not conclusive. We do know, however, that when peanuts are consumed, peanut agglutinin does make it through the gut lining and ends up in the blood stream

Something about peanuts also appears to make them uniquely atherogenic, i.e. likely to promote plaque formation in the arteries. As it turns out, scientists use peanut oil to induce atherosclerosis in rats, rabbits, and primates. Researchers believe that the lectins in the peanut oil are the cause of the atherogenicity. When the lectin content of peanut oil is reduced through an aggressive “washing” process, the narrowing and hardening of the arteries is also reduced.

3. Aflatoxin

Aflatoxin might be the scariest thing about peanuts and the best reason to avoid them.  Aflatoxin is a mold that grows on peanut crops and it’s also a potent carcinogen. Studies from India, China, and Kenya have demonstrated definitive correlations between aflatoxin exposure and liver cancer – in humans, not rats!  In fact, the International Agency for Research on Cancer has classified the common B1 strain of aflatoxin as a “Group I carcinogen” that’s capable of raising the risk for cancer.

True, substandard growing conditions in developing countries likely make those crops more susceptible to aflatoxin growth, but if you’re consuming peanuts and peanut products regularly, there’s no question you’re ingesting some aflatoxin and chronic, low-level exposure has been associated with liver cancer. Evidence has shown that regulatory standards don’t do enough to protect us from the dangers of aflatoxin and often those standards aren’t even enforced.   In the U.S., peanuts are the crop most commonly contaminated with aflatoxin. Corn and cottonseed rank nearly as high on the list.

Milk and cheese are sometimes found to contain aflatoxin as well (yet another reason to give up dairy!) and you have no way of knowing for sure what your intake level is, and, if other factors pre-dispose you for cancer development, what amount of peanut/aflatoxin consumption might be enough for those cancer cells to progress to the next stage of development.  Solution? No peanuts. That was and still is my calculation.  Cancer development is multifactorial but it’s pretty clear that aflatoxin exposure tips the scales in favor of disease formation, while avoiding its obvious sources – to the extent possible -is one of those controllable risk factors that can make a diagnosis less likely.

Again, the amount of aflatoxin in a handful of peanuts or a spoonful of peanut butter might not be harmful but most people I know who consume peanut products are doing so fairly regularly, as in several times each week and have been for years. Since they’re also likely being exposed to aflatoxin from other sources, the risks are amplified.  Aflatoxins are quite stable compounds and survive relatively high temperatures with little degradation.  So don’t think that processing peanuts into peanut butter takes care of the problem.

More problems with peanuts


Peanuts have a high oxalate content. If the concentration of oxalates in our urine becomes too high, kidney stones can form. Oxalates have also been shown to interfere with calcium absorption.


Depending on growing conditions, peanuts can accumulate high levels of the heavy metal cadmium, a known carcinogen. Chronic cadmium exposure can lead to a variety of health problems, including bone and nervous system damage and cancer.


Peanuts are one of the most pesticide-contaminated snacks consumed by Americans. The USDA Pesticide Data Program found 8 pesticides on peanut butter, including piperonyl butoxide (PBO), a highly toxic substance that may lead to a range of short- and long-term effects, including cancer and liver and nervous system dysfunction.


Peanut crops are often rotated with cotton crops and cotton crops are known to receive numerous applications of glyphosate, the main ingredient in the herbicide Roundup made by the Monsanto company.  Glyphosate is classified as a probable human carcinogen  by the World Health Organization’s International Agency for Research on Cancer. U.S. regulators have set an acceptable daily intake (ADI) for glyphosate at much higher levels than other countries consider safe.

Yes, other foods contain some of these same toxic compounds but most Americans aren’t loading up on spinach and shellfish!

One important exception

Upending conventional wisdom on the subject, several recent studies have demonstrated that prenatal and infant consumption of peanut butter can lower the risk for childhood peanut allergies, especially among high-risk youngsters. Very little is needed.  A small serving for an infant can provide protection for at least a year.

Tips for safer peanut consumption

If you can’t give up peanuts completely, at least try cutting back and consider some of these steps to minimize your disease risk:

  • Choose Valencia peanuts, a variety grown in New Mexico, where the drier climate means less aflatoxin contamination. I’ve seen them at Trader Joe’s and Costco stores.
  • Buy organic peanuts to avoid pesticides, another potential source of carcinogens.
  • The highest levels of aflatoxin have been detected in grind-your-own peanut butter found at some health food stores.  The big supermarket brands like Jif and Skippy were actually found to have lower levels, although the partially hydrogenated oils and added sugar they often contain present their own health issues. Read the label.
  • Certain nutritional supplements such as whey protein and ginseng, have been found to counteract some of the dangerous effects of aflatoxin, as has chlorophyll.
  • Other supplements – dandelion root, milk thistle, marshmallow root – can help cleanse the liver and activated charcoal may be helpful in binding to and removing aflatoxin from the body.
  • Much of the omega-6 fatty acids in a jar of peanut bar will be in the oil that settles at the top of the jar. Pour this off to lower your exposure and add a safer oil like macadamia if the consistency is too dry.
  • Ensure you’re taking in adequate omega-3’s from supplements and fatty fish and limiting your omega-6 intake from sources other than peanuts.  This will help get you closer to an optimal 6:3 ratio.

The bottom line

Like many foods, peanuts are both good and bad.  You need to decide for yourself if the bad outweighs the good. And be honest about how much you’re eating and how often. After weighing the evidence, I’ve determined that any health benefit ascribed to peanut consumption is far outweighed by the potential harm associated with it.

A handful of peanuts on occasion is probably fine.  But I just don’t know many people who consume them that way.  Peanuts are a trigger food for many, more likely to initiate a binge than most foods I’ve come across. There are people out there who eat a peanut butter sandwich every day.  And that’s where you have to start worrying about the long-term health effects. The average American is exposed to – and in some cases, bombarded with – lectins, omega-6 fatty acids, and aflatoxins – from a variety of other sources as it is.  I wish peanuts were as healthy as they’re sometimes made out to be because I used to love them but they just have too much going against them. I’ll stick to my homemade sprouted almond and cashew butter.

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