Nightshades are a high lectin food group that is often associated with many of the joint, muscle, and bladder issues I see in my office.

Nightshades are part of the Solanaceae family, a family with more than 2,000 plant species, many of which are inedible and poisonous. Our ancestors were smart—they avoided consuming these foods in high quantities due to their questionable nature.

Which foods contain nightshades?

Nightshades include eggplants, peppers (bell peppers, green and red chilies, jalapenos, pimentos, habaneros, etc.), okra, potatoes, tomatoes, pepino melons, huckleberries, gooseberries, and tobacco.

You should be happy to hear that sweet potatoes (which may be labeled yams in the store) are just fine. What is not fine, though, are the gogi berries, ashwaganda, and ground cherries that many of us use as supplements.

Spices to avoid include cayenne, chili, ground red pepper, crushed red pepper, curry powder, and paprika. Also, try to avoid any ingredients that are listed as “natural flavorings.” Basically, all the good stuff.

I also recommend avoiding cashews from its cousin poison ivy family. Finally, although black peppercorns are technically not a nightshade, I have found that many folks to have a sensitivity to it.

How do nightshades affect my health?

Do you have unexplained pain and tightness anywhere in your body? Nightshades are notorious for their pro-inflammatory properties. In addition to their inflammatory lectin content, nightshades are considered “calcinogenic,” which means that they allow excess calcium to accumulate in soft tissue, leading to pain and loss of function. How, you might ask? Nightshades contain high amounts of calcitriol, a potent form of vitamin D that increases calcium absorption. Since excess calcium is toxic to our bodies, we hide it in our tissues. Calcium can build up and cause arterial plaque, hardened tendons and ligaments, scarred kidneys, bone spurs, etc.

High consumption of nightshades may lead to elevated blood sugar levels which can contribute to inflammation.

Nightshades have also been found to be a potential trigger for autoimmune conditions.. 

Why are some folks more sensitive to nightshades than others?

Overall micronutrient deficiency may make you more susceptible to nightshade issues.  If you don’t have enough magnesium or vitamin K2 or if you have too much vitamin D, you might be more prone to accumulating too much calcium. Add too many nightshades to the diet, and you might just overload the system.

As a side note, K2 is very interesting. If you have gut issues, you might not be able to produce vitamin K2, which can affect calcium levels. In the study “The Effect of Vitamin K2 on Experimental Calcinosis,” researchers induced calcinosis in rats by giving them very high amounts of vitamin D. When countered with vitamin K2, calcification was suppressed regardless of vitamin D status.

Nightshades also contain alkaloids, a know toxin.

What are alkaloids?

Alkaloids act as the plant’s natural bug spray. Have you ever noticed a green tint or “eyes” on potatoes? Those are glycoalkaloids, and they should be avoided. Alkaloids are so toxic that the FDA sets an allowable upper limit of 20 mg of alkaloids per 100 grams per fresh weight of potato. If the level of alkaloids exceeds 20 mg, those potatoes cannot legally be sold in stores. Fortunately, the vast majority of glycoalkaloids are found in the skin, which can easily be removed.

Glycoalkaloids inhibit the breakdown of a neurotransmitter called acetylcholine, which is responsible for muscle contraction. Dr. Marvin Childers believes that the result of this prohibited breakdown may be “…paralytic-like muscle spasm, aches, pains, tenderness, inflammation, and stiff body movements.”

Not surprisingly, alkaloids have been shown to cause gut irritation. It stands to reason that as a natural pesticide, they would adversely affect our gut flora. Again, this may lead to leaky gut and its concomitant issues.

Alkaloids such as the capsaicin found in chili peppers are helpful for reducing pain by altering pain messages, but they can be an irritant to our skin, eyes, and mucous membranes. More importantly, there is evidence that capsaicin also makes us more likely to wind up with leaky gut.

Finally, nicotine from tobacco (also a nightshade member) deals a double whammy to our health. In addition to being addictive, nicotine inhibits healing.

How can I minimize reactions to nightshades and alkaloids?

To help minimize glycoalkaloids,  Health Canada recommends:

Potatoes

• Store potatoes in a cool, dry, dark environment to minimize glycoalkaloid formation (i.e., the “eyes”).
• Cut away any parts of a potato that show signs of greening, physical damage (cuts or bruises), rotting, or sprouting. In severe cases, discard the entire potato.
• Peel the skin from potatoes to reduce glycoalkaloid levels. Do not assume that the concentration of glycoalkaloids in a potato has decreased if the green color diminishes after storage in a dark environment.
• Avoid the consumption of potato sprouts, flowers, and the area around the “eyes.”
• Do not eat raw or cooked potatoes that taste bitter or cause a burning sensation in the mouth.”

Tomatoes

• Consume ripe tomatoes: glycoalkaloid levels decrease as the fruit matures and ripens.
• Consume green tomatoes and products made with green tomatoes only in moderation.
• Do not consume the green parts of tomato plants such as the stem or leaves.

Elimination Diet

The most effective method is a 1-2 month elimination diet to calm down the immune system.  Food then can be reintroduced to determine if it still a problem for you. 

Other methods include Cocoa pulse testing and advanced food sensitivity testing through Cyrex Labs. This lab looks at the food in its raw and cooked forms as well as the lectin components.