Remember the movie “Attack of the Killer Tomatoes”?  That was fiction, but some alarmists would have us believe that the tomatoes and potatoes on our plates are really out to get us.

I recently got an e-mail inquiry from an MD who said he had read that solanine in tomatoes, potatoes, and eggplants could be responsible for essential hypertension and a number of GI complaints, as well as symptoms of rheumatoid arthritis, apparently through their inhibition of acetylcholinesterase. He had looked for supporting scientific studies and hadn’t found any. He wondered if I had seen any such studies. I looked too. I couldn’t find any either.


Tomatoes originated in the New World. They suffered from guilt by association because they were related to the deadly nightshade. Early on, they were used for witchcraft and as an aphrodisiac (“love apples”). They were slow to gain acceptance in Europe and the US, not coming into common use until the early 1800s. Thank goodness they finally did: without them, Italian food just wouldn’t be the same. Potatoes, another import from the New World, were also suspect: they were even accused of causing leprosy. Tomatoes are technically a fruit, although they are generally classified as a vegetable. Remember the attempt to count ketchup as a serving of vegetables in school lunches?

Solanine Poisoning Is Real

Solanine is indeed a poison in large doses, causing everything from gastrointestinal symptoms to hallucinations, paralysis and death. Large amounts are toxic, but the amounts usually found in food are innocuous. It is poorly absorbed and rapidly excreted. It is estimated that it would take 2–5mg per kilogram of body weight to produce toxic symptoms. A large potato weighs about 300g and has a solanine content of less than 0.2mg/gm That works out to around 0.03mg per kilogram for an adult, a hundredth of the toxic dose; I figure a murderous wife would have to feed something like 67 large potatoes to her husband in a single meal to poison him. Unless he’s a phenomenally big eater, arsenic would be a better bet. Potatoes that are diseased with blight or that have sprouted have a larger than usual amount of solanine. They will have a bitter taste and often a green discoloration; such potatoes should be avoided. Even integrative health guru Andrew Weil is not afraid of solanine, pointing out that there hasn’t been a single case of solanine poisoning in the US from eating potatoes in the last 50 years.

Solanine Toxicity Syndrome Isn’t

I found information about “Solanine Toxicity Syndrome” on the website of a chiropractor who uses bogus muscle testing (AK) to diagnose it. He finds that almost all arthritic patients test positive. He claims that in sensitive patients, solanine can:

  • act as an endocrine disruptor especially to the thyroid
  • cause chronic joint pain, arthritis (all forms), joint inflammation- this is due to solanines ability to remove calcium from the bones and deposit it in any weak or genetically predisposed area of the body
  • for the same reason it can be a major contributor to osteoporosis (since it removes calcium from the bones) and arteriosclerosis (it can deposit the calcium in the blood vessels)
  • “leaky gut” as well as IBS
  • appendicitis
  • birth defects including spina bifida
  • depression (correcting it in one patient stopped their strong suicidal tendencies)
  • migraines
  • greatly interfere with calcium and vitamin D absorption, despite supplementation

Scientific Evidence

This will be a very short section. He doesn’t provide references. I looked for credible published evidence to support these claims. I couldn’t find a thing.

Testimonial “Evidence”

He describes his moment of epiphany. While he was treating one of his chiropractic patients, he happened to mention that he had been having pain, stiffness, and swelling in his hands, especially in the mornings (symptoms suggestive of rheumatoid arthritis). The patient asked him if he had eaten eggplant parmesan last night. He had! There you go! That must mean that dietary solanine is hazardous to your health, right?  For someone who believes in AK, that was easy enough to believe. Practice makes perfect: the White Queen in Through the Looking Glass practiced believing as many as six impossible things before breakfast. Believers don’t need no stinkin’ science.

There are a number of testimonials in various places on the Internet from individuals who claim to be unusually “sensitive” to solanine, but no controlled studies to support such claims.

Should We Avoid All These Foods?

Solanine-containing foods from the nightshade family include:

  • potatoes
  • tomatoes
  • paprika
  • eggplant
  • peppers

Foods that are not part of the nightshade family but that also contain solanine include:

  • Blueberries
  • Apples
  • Cherries
  • Sugar beets
  • Huckleberries
  • Okra
  • Artichokes

All these foods can be part of a healthy diet. Their solanine content is not a concern. It’s hard enough to get people to eat their vegetables without this kind of irresponsible fear-mongering.

Bottom line: Avoid green potatoes; otherwise, no worries!

Posted by Harriet Hall

Harriet Hall, MD also known as The SkepDoc, is a retired family physician who writes about pseudoscience and questionable medical practices. She received her BA and MD from the University of Washington, did her internship in the Air Force (the second female ever to do so),  and was the first female graduate of the Air Force family practice residency at Eglin Air Force Base. During a long career as an Air Force physician, she held various positions from flight surgeon to DBMS (Director of Base Medical Services) and did everything from delivering babies to taking the controls of a B-52. She retired with the rank of Colonel.  In 2008 she published her memoirs, Women Aren't Supposed to Fly.