Nightshades and Inflammation: The Real Science

Should You be Like T. Brady and Avoid Them?

Are tomatoes, eggplants, peppers, potatoes, and other fruits/vegetables causing inflammation to run amok in your body? Here’s the actual science.


Tom Brady? He don’t eat no stinkin’ nightshade vegetables, and as such, tens of thousands of people who are easily influenced by celebrity fools in general don’t eat them either. I even heard nightshades are why he and Giselle broke up; something to do with him catching her in flagrante delicto with a Japanese eggplant.

And the Paleo people? They might eat nightshade vegetables on a dare or if their shaman or animal gods sent them their blessing, but they’re wary about them.

Why do all these people have no love for tomatoes, eggplants, potatoes, or peppers, all stalwart members of the nightshade family? Well, as far as the Paleo people, the plants that comprise the nightshade family allegedly didn’t grow anywhere near where man first lived, and that disqualifier is generally sacrosanct to their dietary belief system.

Beyond that, Brady and some of the Paleo people believe that eating from the nightshade family will kill you, kill you dead. Well, maybe not. More likely cause some chronic low-grade inflammation that can be pegged as the cause of anything from depression to weight loss/gain to an inability to love.

Me? I love nightshade vegetables, all the common, edible ones at least. Me and eggplants? Tight. Potatoes? We’re more than just friends. And peppers? My mouth has been on fire since my first take-out Thai dinner from 30 years ago. Pad si ew-whee!

But has this love of nightshade vegetables caused me harm that I’m not aware of? Are the people who avoid them right? Let’s first look at the history of this group of vegetables (most are actually fruits, but let’s not quibble) to see where these fears originated.

Wolf Peaches and Thomas Jefferson

The nightshade group of plants makes insect-repelling alkaloids (nitrogenous organic compounds) that can, under certain situations, have harmful effects on humans. There are two categories of these plants, edible and inedible. The edible ones include all the aforementioned fruits/vegetables, in addition to artichokes, goji berries, huckleberries, and the Ayurvedic herb ashwagandha.

The inedible ones include tobacco, mandrake, and belladonna. It’s perhaps the last one on the list that did the most to stigmatize nightshades. Belladonna, you see, contains atropine, which slows down the heart. Give or take too much and the heart stops. It was popular among ancient Roman muckity-mucks who used it to eliminate their rivals.

“Claudius (whispering ‘you Roman pig’ under his breath), come drink some of my fine vino. Please excuse the slightly bitter aftertaste.”

But it wasn’t until well over a thousand years later that the Italian botanist Pietro Andrea Mattioli perceptively linked the tomato and eggplant, as well as mandrake and the aforementioned belladonna, together. Mattioli simply saw that the plants shared some morphology and thus, using logic, assumed they were related.

As such, all these related fruits/vegetables were considered poisonous to varying degrees. However, it needs to be pointed out that, unlike belladonna, none of these other nightshades contained atropine, but some did/do indeed contain another alkaloid – solanine – which, when eaten in sufficient quantities (lots), can cause nausea, diarrhea, fever, headache, and joint pain.

(Cattle, sheep, and pigs, however, are particularly sensitive to solanine, but that observation might, at least in part, have arisen from the fact that, unlike most humans, those animals eat the solanine-rich vines and leaves of plants like tomatoes and potatoes, items considered unpalatable to humans.)

However, it should be said that the nightshade plants are used in the manufacture of other potentially toxic alkaloids like morphine, quinine, nicotine, and strychnine.

But don’t worry, these toxic alkaloids are found in very specific members of the nightshade family, plants you wouldn’t normally eat or even encounter. Case in point, strychnine is derived from a nightshade plant found in India, Sri Lanka, the West Indies, and parts of Australia. But most of the nightshade plants we encounter in our daily Western lives are exceedingly benign, even though they were initially much maligned.

Consider the genus-species name of the much-beloved tomato: Solanum Lycopersicum, which stems from its common mid-sixteenth century name: Wolf peach – peach because it has a luscious appearance and wolf because of its alleged poisonous qualities, an analogy to the poison-sprinkled meat tossed out as bait to kill wolves.

But the only alkaloid tomatoes contain is a wimpy one known as tomatine. Even so, it appears mostly in the stems and leaves and in the green fruit, from which it disappears as it ripens. Its dissolution is almost regrettable, though, as recent research has found tomatine to be a fairly potent anabolic that also reduces cholesterol. (I’m surprised I haven’t seen or noticed any tomatine supplements on the market yet.)

Anyhow, “wolf peaches” were mostly shunned in Europe and America – partly because of their “poisonous” nature and partly because of their association with witchcraft – until they found an unlikely champion: Thomas Jefferson. He grew them in his garden and often included them in presidential dinners. Slowly, fear of the wolf peach dissipated… well, until people like Tom Brady scared the hell out of impressionable people.

I don’t mean to suggest there’s nothing to any of the concerns about nightshades. They can, when eaten in sufficient quantities, cause some people to experience negative side effects. I doubt, however, anyone, aside from “Eggplant Eddie” from Akron, would choose to eat, for example, a number or amount of eggplant in a single setting sufficient to set these side effects into motion.

But it seems certain that there probably are people out there who are sensitive to certain nightshades and might indeed experience some inflammation as a result. With all that being said, let’s see what the research says.

Inflammatory or Anti-Inflammatory?

While they’re not destroyed by cooking, both boiling and frying reduce the concentration of solanines in foods. Secondly, if they are ingested, solanine is poorly absorbed by the body and rapidly ushered out the urine and fecal sphincter doors.

Lastly, the highest concentration of solanine is found in potato sprouts and areas that have turned green from sun exposure. Last time I checked, breaded potato sprouts weren’t on the Applebee’s appetizer menu, and the only people who eat green potatoes are those who were raised by feral hogs.

But what about alleged inflammation and arthritis? Research has found little to no evidence that nightshades have any effects on joints or arthritis. Quite the contrary, a 2016 study found that eggplants have anti-inflammatory effects. Another study performed in 2018 suggested that solanine itself could be a valuable compound in the treatment of inflammatory diseases.

There’s also the emergence of another nightshade alkaloid, anatabine, which can potentially reduce joint pain, stiffness, and improve functionality in patients with osteoarthritis or hinky joints.

Even the Arthritis Foundation recommends eating those infamous wolf peaches as part of an anti-inflammatory diet. Further, many of the nightshades are part of the Mediterranean diet, considered by many to be the most healthful diet in the world.

These alleged anti-inflammatory, or at least benign, effects might be potentiated by the rich assortment of polyphenols and carotenoids contained within these plants, many of which are known to reduce inflammation.

So, Are Nightshades Completely Off the Hook?

There are some old studies that found that high concentrations of solanine damaged the gut linings of mice, resulting in colitis. However, more recent research found the opposite. That being said, it’s possible that some people who already suffer from undue or increased levels of inflammation might find their situation worsened by eating nightshades.

If you’re one of these people, or at least someone who suspects that nightshades might be upsetting their health mojo, the answer is simple: Just eliminate all nightshades from your diet for two weeks and then slowly re-introduce them, one at a time, back into your diet.

But if you’re simply following Tom’s lead or are influenced by the intransigent views of Paleo diet practitioners, cut it out. These fruits/vegetables are far too valuable, nutrient-wise, to forever cut from your diet.

If you need to fight inflammation, or suspect that you do, pull out the old standbys:

  • Fish Oil – Omega-3 fatty acids have super strong anti-inflammatory properties. Use a high-dose supplement such as Flameout.
  • Nuts and Seeds – Walnuts, almonds, cashews, and pecans all contain anti-inflammatory compounds.
  • Olive Oil – Quality olive oil contains large amounts of oleocanthal, a strong anti-inflammatory.
  • Fruits and Vegetables – Nearly all of them, because of the polyphenols and carotenoids they possess, put the kibosh on inflammation.

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References

References

  1. Pedro Ruiz Castro, et al. Anatabine ameliorates intestinal inflammation and reduces the production of pro-inflammatory factors in a dextran sulfate sodium mouse model of colitis, Journal of Inflammation, 24 August 2020.
  2. Hanjo Hellman, et al. Antioxidants in Potatoes: A Functional View on One of the Major Food Crops Worldwide, Molecules, 2021, May, 26(9).
  3. Im Kyungtaek, et al. In Vitro antioxidative and anti-inflammatory activities of the ethanol extract of eggplant (Solanum melongena) stalks in macrophage RAW 264.7 cells, Food and Agricultural Immunology, Vol. 27, Issue 6.
  4. Zhao Linn, et al. Steroidal alkaloid solanine A from Solanum nigrum Linn. exhibits anti-inflammatory activity in lipopolysaccharide/interferon γ-activated murine macrophages and animal models of inflammation, Biomed Pharmacother, 2018, Sept. 105:606-615.
  5. T.O. Ostreikova, et al. Glycoalkaloids of Plants in the Family Solanaceae (Nightshade) as Potential Drugs, Pharm Chem J., 2022;56 (7):948-957.
  6. Rebecca Rupp, How Carrots Won the Trojan War, Storey Publishing, 2011, pp. 314-339.
  7. James Wong. You Say Potato…, New Scientist, 31 Oct. 20
3 Likes

This is an interesting read. Aside from a general preference for spicy foods, I’ve been taking capsaicin pills as an attempt to control pain and inflammation in a replaced elbow. This was recommended by another injured lifter in my gym and seems to work. I assumed that whatever the body does to combat the agitation from capsaicin has some carry over benefit to other inflammatory contributors. I wonder if this could be true for the compounds mentioned in the article?

Any plans for an anatabine supplement in the works?

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Thanks! Capsaicin inhibits COX-2 enzymes, much like curcumin or NSAIDS. I don’t know if its initial burning effect has any relation to that, though. Worth researching, though. (No, no plans for an anatabine supplement right now.)

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It is interesting. I am a celiac and have had considerable gut damage in my life. If I have a gluten exposure, nightshades tend to have an allergy like effect with itching and swelling. This greatly diminishes as I heal.

I think a lot of nutritional studies overlook the overall gut health. This is by necessity because doing a gut biopsy is impractical.

Atropine certainly doesn’t slow the heart, quite the opposite. It’s an anticholinergic.

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Good article. One minor adjustment on the function of atropine however. Atropine is in fact an anticholinergic as it inhibits acetylcholine and will induce tachycardia or high heart rate, no lower heart rate. The medical condition associated with situations where overdose or poisoning can occur causes anticholinergic syndrome which is an uninhibited parasympathetic response that can be lethal. It certainly does not change the intent of the article, and, as always, very good information and i very much enjoyed it!

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Atropine does not slow the heart at all…

Thank you, I never understood the hate on nightshades. Maybe it’s because I grew up in an Italian family and things like tomatoes, eggplant, peppers and artichokes are mainstays. Always baffles me when people say to restrict broad ranging groups of food but ignore that entire populations that eat them with no issues. I understand that some individuals may have an issue but that’s not a reason for everyone to exclude them.

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You’re right. Thank you. However, in low doses, atropine can paradoxically slow the heart, so much so that bradycardia can set in.

True! As an anesthesia provider I use atropine occasionally in code situations, but more often with intraoperative bradycardia. I’ve not experienced the paradoxical low-dose affect, but it is a known risk. In doses one would receive from dietary plant sources it’s certainly possible this is what you’d see—bradycardia.

Always enjoy your articles. Have been a fan since days of MM2K.

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Capsaicin can also stop minor heart attacks, as it opens the vascular pathways, plus it detoxes those hard to hit areas. Oh, and it makes me high.

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I’ve had diverticulitis several times and it has seemed to have healed now while I’ve been doing the newer fad of avoiding seed oils and lectins and being almost carnivore.

I cannot say how much, if any, of my improvement is do to avoiding lectins. I have tried ashwagandha (mentioned in the article as edible) twice before and that definitely and violently did not agree with my gut. So that lends anecdotal evidence to the theory of lectins being bad for your gut lining.

There is something to good gut health but you’re right that it’s hard to experiment with.

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