HomeAboutThree Generations of Nightshade Intolerance: One Family’s Discovery

Three Generations of Nightshade Intolerance: One Family’s Discovery

The summer before his tenth birthday, my son whispered with worry that there might be some blood in the toilet. He’d flushed the evidence and I was cheerfully doubtful, trying to reassure us both. But a few days later I saw that he was right. We visited the doctor, securing antibiotics for what we were all sure was a simple infection.

But the bleeding didn’t stop, and within three weeks he was writhing in agony, night after endless night. Thus began a six month nightmare that included the diagnosis of two serious autoimmune diseases and one very important dietary discovery: He really shouldn’t eat nightshades.

What’s a nightshade? They are, primarily, tomatoes, potatoes, peppers, and eggplant. They look quite different from each other, but are part of the same plant family and are linked by chemistry. Nightshades are renowned for their ability to produce some very interesting, valuable, and sometimes dangerous compounds.

When the first few doctor’s appointments didn’t yield a simple solution, I began doing some research, and realized there might be a dietary component to my son’s problems. Tomatoes were actually my first suspect. My son had always been lean and a picky eater, and that summer he had learned to make his own pizza bagels. And I let him, whenever he wanted. He used my homemade sauce, rich with olive oil and onions and organic tomatoes. He made a lot of pizza bagels. Pizza is not exactly a health food, but for a boy of his slender build and furious metabolism this seemed fine.

To great protest, I removed the pizza bagels—and all tomatoes—from his diet. That helped a lot, but not completely. The pain was less frequent. We tested dairy, then wheat—two common irritants. For a while we feared it was chocolate. He hoped it was broccoli.

But we just couldn’t get a handle on it. Tomatoes were clearly guilty, but also not the only culprit. Removing any single item didn’t seem to help.

After a few months of tests and procedures we had our first autoimmune diagnosis. It helped explain the ongoing pain, and also perhaps why we weren’t getting the clearest signal from our dietary experiments: His gut was inflamed, and appeared to be amplifying the smallest dietary insults.

And because it was clear that tomatoes weren’t the only problem, it was hard to even be certain that tomatoes WERE a problem. The medicines weren’t working and the food wasn’t working. We were exhausted, confused, and scared.

Finally, one night after Christmas, my son and I had a classic parent-child argument about the oven fried potatoes I’d prepared with dinner. He said “No thanks. I said “You can’t eat tomatoes anymore, so you need to learn to eat other vegetables.” He gave in. And soon he was in unbearable pain again, screaming through the darkest hours of the night.

That’s when I made the nightshade connection. You wouldn’t think to look at it but the potato and the tomato are actually close botanical cousins. A neighbor of ours couldn’t eat nightshades. Could they be the root of all this pain?


Over the course of millions of years the plants in the nightshade family have evolved chemical weapons to keep insects and other animals from eating them. Capsaicin, the hot molecule in peppers, is sensed by mammals but not birds. Evolutionary biologists believe that it discouraged browsing mammals. That left the fruits for birds, who are better at seed dispersal. Other nightshade chemical ‘inventions’ include nicotine, one of the most infamous and influential substances in human history.

The nightshade arsenal includes a family of poisonous chemicals called glycoalkaloids. This poison has an upside for the human palette. In small doses its funky biochemistry probably contributes to the extraordinary and intriguing nightshade flavors.

Flavor is a secondary concern when your food is hurting you, and for my son the searing pain only went away once we removed all nightshades. Finding them took some work. The last mystery was solved when I discovered he was getting Cheez-Its and classic Goldfish crackers at school. Both contain paprika—who knew it was such a common ingredient in snack food? A handful of these crackers was enough to provoke a night of agony.

We reported our discovery to the doctor, who ordered allergy tests. They showed nothing, and by this time the doctor was focused elsewhere. He had identified a second and potentially more terrifying autoimmune disease.

A year went by, during which the combination of a no nightshade diet and heavy duty medicine combined to control his diseases. (Please note: His autoimmune diseases were NOT cured by removing nightshades. His SYMPTOMS did recede. He still takes medicine to treat his condition. I suspect that removing the regular irritant of nightshades helped his system to heal, giving the medicine room to work. But medication still plays a significant, if imperfect, role in managing his health.)


Meanwhile, I cooked nightshades for myself and my daughter. I love my son, but wasn’t ready to give up all of my favorite foods in solidarity. I also quickly discovered that I hardly knew how to cook without them.

But the next summer, when my daughter left for 7 weeks of camp, I decided it was the perfect time to experiment on myself. I wanted to know if nightshades affected me. As a concerned parent who could read medical literature I’d been geeking out trying to make sense of the research about diets, inflammation, autoimmune disease, and food sensitivity. At first I wanted to understand my son’s complex diagnosis better.

I read both journal articles and patient forums related to my son’s diseases and I began to see some overlap with my own health. A few—seemingly simple—complaints had emerged over the last decade. Was it just aging with a side-order of stress, or could nightshades also play a role? On the autoimmune side I had touch of vitiligo, and an annoying red patch at the back of my scalp. Sometimes my joints hurt and my wrists and fingers felt slightly inflamed. I had a sour stomach far more often than I enjoyed or cared to admit.

Elimination diets can be hard but since I was already cooking nightshade free for my son I simply shared his diet. By the end of the summer my system was seven weeks nightshade free and primed for the test. When we arrived at camp to pick up my daughter, the lasagna on the menu was the perfect challenge. I ate it with gusto, savoring the peppers and tomatoes in my salad.

The next morning my body was aflame. Any active 40-something has old injuries, but that day decades-old injuries raged in my body. My wrists (repetitive stress), my right elbow (disc sports), and my right ankle (volleyball) all felt like they were still healing. My pleurisy—an inflammation of the tissues that line the lungs and chest cavity, and that can cause a sharp pain when breathing—was acting up. The patch on my scalp was lit. My knees and hips were uncommonly stiff.

Most unexpectedly I was high, doped, chemically altered. I didn’t trust myself to drive for 3 days. My neighbor calls this tomato brain, and it was a new and deeply troubling sensation. I felt like I had aged a decade overnight. It was a stunning discovery. I was done with nightshades.


A year later, another surprising piece of the puzzle emerged. My father does medical mission work in Mexico every winter, and like many travelers he sometimes struggles with the different food, stray microbes, and the resulting GI discomfort. But this time was different: He’d gotten much sicker, and despite several courses of antibiotics things just weren’t normalizing. As a family doctor he’d observed what my son and I had experienced with nightshades, and decided to try removing them from his own diet.

This was a radical decision. My dad is a devoted gardener who grows outstanding tomatoes and potatoes. Some of my earliest food memories involve his extraordinary home-grown produce, particularly his potatoes and tomatoes. I would have put the likelihood of him voluntarily eliminating these foods from his diet at something close to zero.

Yet with the nightshades gone his GI difficulties resolved. And like me his own discovery went further. He loves to work around his property, but joint pain had begun to limit his ability to do manual labor. But when he removed nightshades he discovered he could be outside substantially longer. He could exercise more comfortably. He was a no nightshade convert.

The family connection continued with my daughter, who has also found it important to limit her exposure to nightshades. She’s not as sensitive to them as the men in our family. But once she left for college and was exposed to substantially more nightshades in her diet, she suffered from heartburn, GI discomfort, and general soreness. As a collegiate swimmer it was this last symptom that moved her to modify her eating. She can occasionally indulge in nightshades, but finds it optimal to keep them at a minimum.


Father, son, grandson, granddaughter.

Three generations of nightshade sensitivity suggests that deep in our DNA a tiny piece of code objects when exposed to nightshades. At least, that would have been the most plausible scenario when my parents attended medical school, in the 1970s. But in the last two decades, science has exposed two more potential mechanisms: the microbiome and epigenetics.

The microbiome is shorthand for the trillions of microorganisms that colonize our every nook and bodily cranny—particularly our intestinal tract. Generally they enjoy a complex and usually healthy relationship with our immune system. The makeup of microbes in our GI tract is strongly influenced by the food we eat, and they in turn interact with our metabolic, immune, and nervous systems in subtle ways that we are only beginning to understand.

Epigenetic changes, meanwhile, are like a memory of the interactions between your environment—including your microbiome—and your genetic code. Genes that control countless processes in your body can be turned on or off by things like stress, nutrition, and infection. Epigenetics is kind of like a track coach, standing there with a clipboard and a clicker, reminding you of both your best time and that month of your junior summer you spent your meager earnings on fast food.

A lot of epigenetic change happens in your GI tract. When you were born every cell in your intestine contained an essentially identical copy of DNA. But over time the environment makes revisions. Some microbes, encouraged by particular dietary regimens, can change the mix of molecular signals. This fine tuning in turn can change whether certain genes in the colon are amplified or quieted. Recent research in animal models shows that a high fat diet changes gene expression in organs beyond the colon. Your DNA is essentially like a giant circuit board, with genes that get turned on and off by both circumstance and design.

We don’t yet know the mechanisms behind nightshade problems. I was initially inclined to believe the microbiome/epigenetic explanation. How else could I develop these problems after the age of 40? Or my dad in his sixth decade? It had to be the environment—some virus or other rogue elements of the microbiome.

But after about two years of no nightshade eating I realized that the health impacts of nightshades may go back much further for me. Twice yearly, in fall and spring, for as long as I can remember, I would catch a terrible cough. It’s an awful, corrosive beast that lasts two or three weeks. Since I’ve removed nightshades from my diet that cough and my pleurisy have largely disappeared. Had I been suffering all of my life because of a basic incompatibility with nightshades?


I’m quite confident that nightshades cause problems for me, and yet I may never know why. While some doctors and scientists aren’t surprised by the idea of nightshade sensitivity, it’s not common or high profile enough to be a research priority. It’s also devilishly complex. As of this writing, my son’s sensitivity to nightshades is still something that has to be entered manually in his chart—there is no diagnostic code, no medically accepted shorthand for what’s going on.

For years I’ve scoured the scientific literature looking for answers, and there’s nothing truly definitive. I’ve learned enough to feel comfortable in asserting that, contrary to very real medical ambivalence and accusations of quackery, nightshades are a problem for some people.

I trust the diagnosis we have made within our family. We’ve identified nightshade sensitivity in three generations. My father, my daughter, and I have tested and retested it via accidental and intentional exposure. I’ve also met other people who feel better when they remove nightshades from their diet.

Are you sensitive to nightshades? I sincerely hope not. The symptoms can be subtle. Determining the cause and effect is difficult. Your doctors may or may not be helpful along the way. And unfortunately, there are still no medical tests, so the only way to find out is to make a guinea pig of yourself with an elimination diet.

And frankly, if you discover that you’re nightshade sensitive it doesn’t get any easier. You’ll find a food system permeated with nightshades. If you’re a cook you’ll have to reprogram your brain. You’ll also find that most restaurant menus are lacking in no nightshade options, and often enough even lacking in the information needed to determine whether there are no nightshade options.

There is a significant upside. If nightshades cause you problems, you’ll feel better without them. Maybe a lot better. And now there is also a new culinary world for you to explore. You’ll find a rough guide to it here in The No Nightshade Kitchen. And hopefully, you’ll be able to add your own chapter.


Click here for more about elimination diets.

If you want to learn more about nightshade science begin here.

For the thoughts of a professional nutritional consultant go here.


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