Nightshade foods contain solanine, a chemical which some people believe may aggravate arthritis pain and inflammation. The Arthritis Foundation say that his is not true. However, if a person feels that certain foods trigger their arthritis symptoms, including nightshades, they should avoid these foods.
Nightshade vegetables are part of the plant family Solanaceae. Some species are toxic, including the belladonna plant, which is also called deadly nightshade. Other species are commonly cultivated and eaten by humans. Common nightshade vegetables include white potatoes, tomatoes, eggplant, bell peppers, cayenne pepper and paprika.
Solanine is found in trace amounts in potatoes and is normally safe, though the leafy stalks of the potato plant and green potatoes are toxic, and solanine poisoning has been reported from eating green potatoes.
A person may be allergic to one or more nightshade vegetables if they experience the following symptoms shortly after eating them: hives or a skin rash, shortness of breath, wheezing, coughing, tightness of the throat, pale skin, and anaphylaxis.
Nightshade vegetables are excellent sources of nutrition, and no research to date has linked them specifically to increased inflammation or other symptoms of arthritis. A person should speak with a dietitian if they are concerned about the effects of a particular food on their health.
Nightshades are the fifth most common food allergy I find clinically. Only wheat, dairy, soy and corn test positive more often. They are a weird group of foods because the common link is the presence of solanine not their appearance or use in the diet.
The allergic symptoms noted above are quite obvious but also rare. More commonly the nightshades irritate the gut, increasing secretory IgA and causing gut inflammation. This leads to leaky gut and ultimately an autoimmune response that very likely will create arthritic inflammation along with other inflammatory responses.
Increased histamine is the most common inflammatory marker, but cytokine and leukotriene production can also occur. If histamine levels are high enough the constitutional signs of allergy will occur. However, most often the patient just experiences chronic low-grade systemic inflammation. They may have musculoskeletal pain, intermittent IBS episodes, headaches, indigestion, and/or fatigue.
There are many anti-inflammatory products than can be effective – vitamin B12, vitamin D, ginger, Boswellia and quercetin, just to name a few. Eliminating most, if not all sources of the nightshades will often eliminate or reduce the need for anti-inflammatory supplementation.
The biggest problem is the processed foods that contain nightshades. Ketchup and many sauces contain tomato and cayenne. Bell pepper and paprika are also commonly added to these concoctions.
The Bottom Line:
The nightshades are a fairly common cause of systemic inflammation and should be considered a potential allergen. This is especially true if elimination of wheat, dairy, soy and corn have not resulted in a dramatic reduction in inflammation.
Source: May 9, 2018 National Institutes of Health