Before I was immersed in the wellness world, I believed all fruits and vegetables were good for you, end of story. Oh, how I miss those simple times. Now that I’m a food writer and certified health coach, I hear from people on a regular basis about why they steer clear of nightshades—a group of fruits and veggies that includes eggplants, tomatoes, red peppers, and white potatoes—or fruits high in sugar.

Triple board-certified functional medicine nutritionist, cognitive behavioral therapist, and The Archetype DietDana James, MS, CNS, CDN, is not here for it. “Women are becoming much more scared of foods: fruit, nightshades, grains…I’m personally frustrated,” she says. Inflammatory articles (pun intended) about foods she is trying to actually get her clients to eat, she says, are getting in the way of people living their best, healthiest lives. How did we get here?

One reason, James argues, is that diets created for people with specific illnesses are being applied to the general public, including the rise of the Plant Paradox Diet. The eating plan was popularized by heart surgeon and cardiologist Steven R. Gundry, MD, when his book titled The Plant Paradox became a number-one best seller shortly after it was released in 2017. (Dr. Gundry has gone on to write several other books, including The Longevity Paradox.)

The crux of Dr. Gundry’s advice comes down to avoiding lectins, a protein that is part of plants’ natural defense systems against predators. “Plants are subject to the same evolutionary pressure that all creatures are,” Dr. Gundry tells me. “That is, the plant that stays alive long enough to have babies and ensures its babies stay alive will always win.” Lectins, he says, protect plants by causing digestive distress and inflammation in those who eat them, and certain plants are particularly high in lectins, such as, you guessed it, nightshade vegetables.

So who’s right? We dove into the Plant Paradox diet and the controversy surrounding it—and gave both experts a change to sound off.

What is the Plant Paradox diet?

For background, it first helps to know exactly what following the Plant Paradox diet entails. Basically, people on the eating plan are told to avoid anything with lectins and any other foods that have been linked to causing inflammation. This includes grains, legumes, nightshades, squash, cashews, chia seeds, pumpkin seeds, sunflower seeds, peanuts, and out-of-season fruits.

It’s restrictive, sure, but there are still plenty of foods left on the table, including: macadamia nuts, pecans, coconut, flaxseed, hemp seeds, olives, dark chocolate, herbs, minimally processed dairy, cruciferous vegetables, avocado, berries, fish, grass-fed meat, and pasture-raised poultry. (Head here for a complete list of foods one can and can’t eat on the Plant Paradox diet.)

Again, the list of healthy foods Dr. Gundry recommends avoiding is long, but he maintains that it’s because eating plants that don’t want to be eaten (i.e. those high in lectins) causes inflammation in the body, and reducing inflammation is the whole goal of the Plant Paradox diet. If you don’t stick to his eating plan, he says it can cause weight issues, leaky gut, and cognitive decline. “A lab test was developed finding that when people ate spinach, corn, tomatoes, potatoes, or soybeans, it not only promotes leaky gut, but also leaky brain because it breaks down the blood-brain barrier,” Dr. Gundry says.

Criticisms of the Plant Paradox diet—and what Dr. Gundry has to say

As mentioned, James (and other health experts) have a lot of problems with the Plant Paradox diet. “There may be some people who are affected negatively by nightshades, but it’s grossly overestimated how many people are negatively affected by these foods,” James says. “Also, nightshades are just one type of lectin. Someone might only have a reaction to nightshades, or one specific type of vegetable, or just wheat [which contains the lectin wheat germ agglutinin], but the Plant Paradox diet is telling people to avoid it all.”

It’s a valid point. How does someone know if they have a problem with all lectins or just one type of lectin? “There is a blood test that shows if lectins are raising the levels of tumor necrosis factor alpha [a cell signaling protein which signals to cells if there is inflammation in the body] in the body, which is a very good indicator that you are reacting [negatively] to them,” Dr. Gundry explains. “It’s not a perfect test, but it’s a pretty good indicator.”

I also asked Dr. Gundry why some people are able to dine on many of the foods on his “avoid” list and have no negative symptoms whatsoever, given that lectins are so potentially toxic. “There are some lectins that we’ve been eating for millions of years and our gut microbiome has gotten used to them,” he tells me, like rice and wheat. But Dr. Gundry says for anyone experiencing any sort of health problems, getting off lectins can help. He says in his 2018 study in which participants with autoimmune disorders avoided lectins, 94 percent of them had no more problematic symptoms within nine months. “We don’t use the word ‘cured,’ but the markers for their autoimmune diseases was gone,'” he says. “We reintroduced lectins—one group at a time, such as gluten or nightshades—and then it went up again. So then we had them avoid lectins again, and again it was gone.”

James is very skeptical. She says research dating as far back as 1999 shows that lectins are only a problem when the gut microbiome is not functioning well. Fix the gut, James says, and then you won’t have a problem with the lectins. James also points out that Dr. Gundry’s protocols says it can help people with autoimmune disorders—an umbrella term that applies to many different illnesses with different symptoms and causes. “There is a spectrum of autoimmune diseases. Is Dr. Gundry referring to illnesses like lupus and MS or the more mild cases, like Hashimoto’s? These are different autoimmune diseases and should not be lumped together. No research study looks at autoimmune disease in aggregative, they look at very specific illnesses to not distort the findings.” To this, Dr. Gundry points to research on various autoimmune diseases, which connects them to an underlying problem.

She also says that health issues such as leaky gut are complicated and linked to more than food; stress can cause leaky gut, for example. “There are a whole host of reasons why you can end up with leaky gut. If you ignore the body for too long, it gets worse and worse. So those that are extremely sick and they ignore their body for some time do become sensitive to an increasingly number of foods,” James says—but that’s not to say that one single type of food causes the illness, she says.

The bottom line

What remains clear about the Plant Paradox diet is that it’s still very controversial. The claims Dr. Gundry makes are radical. And in James’ experience, many people are avoiding foods that otherwise won’t cause them digestive distress or any troubles whatsoever. (Though Dr. Gundry would say otherwise.) Yet many other people anecdotally have said that the eating plan has helped them regain control of their health.

The big point James wants to make is that addressing gut health is more complicated than just assuming lectins are the culprit—which is why it’s so important to work with a trusted professional to figure out the root of your digestive issues before jumping into a restrictive diet, no matter what it is.

Originally published August 2, 2019. Updated February 5, 2021.