You've probably have heard the term "nightshade" vegetables. Some people think they are life saving plants, others consider them poisonous.
Nightshades belong to a scientific family of plants called Solanaceae, which include several thousand species of flowering plants, and most of these plants are not edible as food. However, there are a good number of nightshades that have been enjoyed as staple foods in diets across the globe for thousands of years. Nightshades include: tomatoes, potatoes, eggplants, bell peppers, okra and spices like cayenne pepper, chili pepper, paprika and curry powder, as well as herbs, like belladonna.
Nightshades are different fruits, vegetables and herbs that have something in common - the presence of two substances: calcitriol and alkaloids.
Calcitriol is a vegetable source of vitamin D. I've written enough about the benefits of this vitamin in previous blogs, so I won't repeat it here.
Alkaloids in food have many health benefits, including antioxidant-related benefits and cancer-protective properties.
Potatoes and eggplants make solanine; alkaloids are part of their natural defense system. They accumulate alkaloids mostly in the greens of the plant (the above-ground part), in the skin, the flesh just below the skin, and the spots where it has started to sprout. These are poisonous parts of the plant, needed to protect it from insects and pests, and can be dangerous to people as well. Solanine can contribute to the development of Irritable Bowel Syndrome (IBS) and can negatively affect intestinal permeability ("leaky gut"), as well as aggravate Crohn's and Ulcerative Colitis problems. 
In a study of 5000 arthritis sufferers, published by the Journal of the International Academy of Preventive Medicine, who eliminated Nightshades, 70% reported relief from aches, pains, and disfigurement. 
So for people with any autoimmune disorders, like Hashimoto's thyroiditis, Rheumatoid arthritis and others, if you want to know if Nightshades negatively affect you, take the 3-month challenge. It can be tricky to avoid tomatoes, paprika and chili powder since these can be found in many popular spices and sauces. And of course ketchup, steak seasoning, and curry powder all contain Nightshades.
If your symptoms improve, then stay away from these foods until you heal your gut. If you see that you are not sensitive to them and your symptoms don't exhibit any change, then enjoy the benefits of eggplants, tomatoes and peppers, which are a great source of fiber, antioxidants, minerals and vitamins, as well as anti-cancer effects.
Capsaicin is the active ingredient in hot peppers and is most commonly recognized for its anti-inflammatory properties, but it should also be noted that it is an alkaloid. It has been shown to benefit digestive health, cardiovascular health and long-term cancer prevention. Capsaicin also has been shown to boost metabolism, as well as suppress appetite, and help with weight loss. And don't forget you can use it topically to help with pain.
Piperine, found in dried black pepper, may prevent new fat cells from forming and prevent weight gain.
Nightshade foods also contain small amounts of nicotine, especially when unripe. Of course, nicotine amounts are much higher in tobacco leaves. Scientists believe that nicotine is a natural plant pesticide.
Nightshades also contain lectins, which are hard to digest and sometimes can lead to food allergies. But soaking lectin-filled beans in water, or cooking them at a high temperature actually deactivates the biological effects of lectins, making them harmless.
As you can see there are many benefits and some possible dangers with eating Nightshades. If you think your symptoms of fatigue, joint pain, digestive problems may be related to Nightshades, try to live without them. But if not, enjoy their healthy benefits!
If you are still not sure whether or not you are sensitive to Nightshades or other foods and eliminating them from your diet was not helpful, there is a blood test that can clarify your sensitivity.
For more information on the effects of diet and lifestyle modifications on your health, please schedule an appointment with Dr. Koganski at 215-750-7000 or www.newtowninternalmedicine.com
 Patel B, et al. Potato glycoalkaloids adversely affect intestinal permeability and aggravate inflammatory bowel disease. Inflamm Bowel Dis. 2002 Sep;8(5):340-6.
 Chiders NF, et al. A relationship of arthritis to the Solanaceae (Nightshades). Journal of the International Academy of Preventive Medicine. 1982, 31-37.