by Linda Hartford on March 18, 2011

Nightshades are members of an enormous family of plants called Solanaceae. Potatoes, tomatoes, sweet and hot peppers, eggplant, tomatillos, tamarios, pepinos, pimentos, paprika, cayenne, and Tabasco sauce are classified as nightshade foods. Peppers includes all peppers including chili peppers, habenero, cayenne pepper and paprika.  Paprika is contained in lots of flavoring mixes and is often listed as“spices” on ingredient labels. Other nightshades include goji berries (an antioxidant), ashwagandha (an adaptogenic herb from Ayurvedic medicine), Cape gooseberries (not normal gooseberries), ground cherries and garden huckleberries (not blueberries).

As a long-term sufferer of fibromyalgia, my goal is pain relief. Using painkillers, without true pain relief just won’t cut it. I usually don’t completely avoid nightshades. But when I start having pain, they are the first to go!! For many people, nightshade avoidance is the answer to long-term relief from pain. Shakeology contains both goji berries and ashwagandha but I have used it daily for over 6 months and have not noticed a reaction to it so far (YMMV).

I know you probably enjoy eating these foods and can’t imagine that they are bad for you in any way. I mean, really, mashed potatoes, the ultimate comfort food??? Well, if you suffer from inflammation, joint pain and cracking, avoiding nightshades will lessen your pain and this is true whether or not the nightshades are the true source of the pain. Sensitivity to weather changes, muscle pain and tightness, morning stiffness, poor healing, arthritis,heart burn or GERD, insomnia and gall bladder problems can all be caused by nightshades.

For those of you who have arthritis or fibromyalgia pain but haven’t tried avoiding nightshades — it’s something you need to try. There is simply nothing else that doctors can do to help somebody in pain when nightshade sensitivity is the cause—because once they eat nightshades again, their pain will return as it was before. Sad but true.


The nightshades cause calcinosis, which is a toxic calcification of soft tissues when eaten by animals. This happens because they contain calcitriol, the most active form of vitamin D. Calcitriol is normally the end product of vitamin D metabolism in humans.  Production of calcitriol, an extremely potent hormone, is very tightly regulated by the kidneys.

Calcitriol signals the intestines to absorb calcium from our diet. While we absolutely need calcitriol to maintain proper bone density, too much calcitriol leads to high blood calcium  (hypercalcemia). Since the heart is affected by an imbalance of minerals in the blood, the body wants to get the calcium levels back down to normal as quickly as possible. The quickest solution for the body is to deposit the extra calcium into the soft tissues. Each hypercalcemic episode likely lasts for only a short while, however, each episode leaves a small deposit behind. Over time, these deposits lead to the condition known as calcinosis.

Overconsumption of calcitriol from nightshade foods can circumvent the kidney’s control and over time lead to calcium deposits in soft tissues such as the tendons, ligaments, cartilage, cardiovascular tissues, kidneys and skin. Osteoarthritis is basically calcium deposits in the soft tissues of joints. Chronic hypercalcemia can lead to generalized vascular calcification, which is coronary artery disease. Nephrocalcinosis is calcification of the kidneys.

Many of us do not notice because it happens so slowly and gradually.


Solanine is a potent poison found in species of the nightshade family, especially potatoes and eggplant. It can occur naturally in any part of the plant, including the leaves, fruit, and tubers. Solanine poisoning is primarily displayed by gastrointestinal and neurological disorders. Symptoms include nausea, diarrhea, vomiting, stomach cramps, burning of the throat, cardiac dysrhythmia, headache and dizziness. Hallucinations, loss of sensation, paralysis, fever, jaundice, dilated pupils and hypothermia can occur in more severe cases.

Potatoes naturally produce solanine and chaconine, a related glycoalkaloid, as a defense mechanism. Potato leaves, stems and shoots are naturally high in these glycoalkaloids. When potato tubers are exposed to light, they turn green and increase glycoalkaloid production. This is a natural defense to help prevent the uncovered tuber from being eaten.

In potato tubers, 30–80 percent of the solanine develops in and close to the skin. If the potato looks green under the skin or has begun to sprout, throw it away.

How toxic are these compounds? The World Health Organization sets an upper limit of 20 mg per 100 grams of solanine per fresh weight of potato. Potatoes above that limit are considered too toxic for human consumption and cannot be sold in stores.

Solanine and related glycoalkaloids are poisonous because they inhibit the breakdown of acetylcholine, resulting in increased level and duration of action of this neurotransmitter. What does this mean? They cause prolonged muscle contractions. This is why people who are sensitive to nightshades or eat a lot of them often feel stiff when they wake up in the morning or sit for extended periods.

Studies indicate that solanine causes exacerbated irritable bowel disorder in mice and gastrointestinal tissue destroyed in Syrian hamsters. Research has linked potato blight in Ireland with birth defects in the following years. Potato blight involves a particular fungus growing on potatoes, causing them to kick in their defense mechanisms and make high levels of solanine. It would be wise for pregnant women to avoid nightshades.


All nightshades contain nicotine, which is why they can be addictive. Is nicotine a problem when we eat it? A large body of research shows that nicotine consumption inhibits proper healing. In one study, nicotine delayed tendon-to-bone healing in a rat shoulder—the equivalent of our rotator cuff.


Capsaicin is an alkaloid found in hot peppers. Capsaicin supposedly has anti-inflammatory properties, but it is actually an irritant for mammals, including humans, and produces a burning sensation in any tissue it comes in contact with.

Spicy peppers are the only plants that contain capsaicin. The active ingredient in pepper spray is capsaicin. It can shut down the lungs—this is why some people have died from pepper spray. Asthmatics should avoid capsaicin in general.

Substance P is released from the terminals of specific sensory nerves. It is found in the brain and spinal cord and is associated with inflammatory processes and pain—it acts as a neurotransmitter to carry pain signals to the nervous system. Capsaicin makes your nerves release almost all the substance P they have and so drugs containing capsaicin are sometimes used to reduce pain. For example, there is an over-the-counter cream containing capsaicin that is promoted to help deplete substance P from local nerve endings and relieve pain.

However, inducing massive releases of substance P on a regular basis leads to a chronic local or systemic depletion of substance P. Substance P is necessary for proper healing because it signals the brain that something is hurt and needs to be fixed. So when you have diabetics using capsaicin cream for their neuropathy, the pain signal is gone and they feel better but they are inhibiting the healing process.

A recent study looked at the use of capsaicin in insulin-dependent diabetic rats. The standard explanation for type 1 diabetes is malfunction and death of the insulin-producing islet cells in the pancreas. Another theory holds that malfunction of the pain nerves surrounding cells in the pancreas can cause type 1 diabetes. Researchers have found that the islet cells in diabetics are surrounded by large numbers of pain nerves that signal to the brain that pancreatic tissue is damaged. When the researchers injected Substance P into the rats, the islet cells began producing insulin normally almost immediately. They also produced insulin for about a month when they were injected with capsaicin. Capsaicin depletes substance P. Although this study was reported as showing a beneficial role for capsaicin, the proper conclusion is that capsaicin has a negative impact for diabetics and their blood sugar control.

Capsaicin receptors have been found in arthritic joints. When they inject capsaicin into mouse knee joints, it reduces blood flow.

In humans, increased consumption of peppers is associated with an increase risk of nasopharyngeal carcinoma and stomach cancer. Researchers found 17 times the risk of stomach cancer in people who self-rated themselves as high consumers of peppers. In people who had tissue biopsies of colon polyps, dysplasia and adenocarcinoma, researchers couldn’t find any substance P in those biopsies. What they found was the presence of capsaicin receptors instead.


How do you find out whether nightshades are causing your medical problems? For many, no relief comes until the diet is totally clear of all these nightshades for at least six weeks. Many people notice an improvement in their pain; sometimes it goes away completely.

If you have strictly avoided nightshades for six weeks, yet still don’t believe your pain has decreased, do a “nightshade party day”: salsa and eggs for breakfast, tomato and eggplant for lunch, potatoes for dinner—just have it all, and have a lot. Eat as much as you can in one day and then watch for symptoms over the next two days. Often there is a delayed onset reaction—there is for me.

But the real question is, why are some people more sensitive than others? Nutrient deficiencies certainly come into play. For example, if you don’t have enough magnesium, you will be more prone to calcinosis. Deficiency in vitamin D may exacerbate the problem. The speed at which one’s liver and kidneys detoxify these compounds plays a huge role, and this is dependent both on genetics and nutrition.

In one study, they gave rats calcinosis by giving them way too much vitamin D2. They found that a high dose of vitamin K2 suppressed experimental calcification of soft tissues induced by vitamin D2. So if you want to avoid problems with nightshades, be sure to eat goose liver, cheese, fatty grass-fed meats and pasture-fed butter—and take your butter oil.

If you suffer from osteoarthritis, you may want to take a vitamin K supplement such as Allergy Research Full-Spectrum Vitamin K softgels, which combine vitamin K1 and vitamin K2.


Even if you are one of those lucky people who don’t seem to have trouble with nightshades, it’s not a good idea  to overdo. Vary your diet so you are not so dependent on these foods. Sweet potatoes, yams and parsnips are good substitutes for potatoes. You can steam cauliflower and mash it with butter and cream but just remember that cauliflower affects the thyroid. As a substitute for chili pepper, use wasabi, horseradish, mustard powder, ginger, or freshly ground peppercorns. There’s no good substitute for tomatoes, so learn to use them sparingly.

Cooking does reduce the solanine levels in potatoes somewhat, and may even help reduce other toxins. The best strategy is to avoid them completely for a long time, until you can completely heal. That means no potatoes, pizza, tomato sauce or Mexican food—but to live pain-free makes it worth the sacrifice.



Dan May 24, 2011 at 8:40 pm

You briefly mention ashwaghanda as containing nightshades, (as other sites do) but don’t go any further. Could you please look into this and try to find out if perhaps the herb contains much lower levels, or a different type of nightshade?

It’s not listed on most sites, so I wonder if it’s truly a problem herb?



Linda Hartford May 26, 2011 at 5:19 pm

Ashwaghanda is a member of the nightshade family, however I have seen sites say that it lacks the poisonous attributes of the nightshades. So, it should not be a problem; however, I think some people are more sensitive than others so YMMV (your mileage may vary). Ashwaghanda is one of the many ingredients in Shakeoloigy. I drink Shakeology every day and have not had a problem. I think bell peppers & potatoes affect me the most but I don’t ever notice a problem when I eat fries.

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