You might have heard that NFL quarterback Tom Brady doesn’t eat nightshades. He even has a book outlining a whole host of things he doesn’t eat and why. While I would take advice on being an NFL quarterback from him, I would decidedly NOT take nutrition advice from him. Most of what he talks about is pseudoscience at best and just silly at worst. But the idea that nightshades are bad for you seems to permeate a lot of the nutrition space. Let’s take a look at what they are and separate fact from fiction.
What are Nightshades?
There are lots of different explanations of why nightshades are called nightshades but no clear reason why they are. Just go with it. There are about 2,000 different kinds of plants in the nightshade family. Most of them are not edible. The few that are edible have been staples in the human diet for a LONG time. Among them: peppers (including the spices made from peppers such as cayenne pepper, chili powder and paprika to name a few), potatoes (but not sweet potatoes), eggplants/aubergines and tomatoes.
Why are nightshades thought to be dangerous?
The logic here is a little bit circular but here goes.
You might have heard that tomato plants are poisonous. However, it’s entirely true. If you were to eat a pound and a half of tomato leaves, that would be a problem. But that is an exceptionally large amount and it would be hard to eat that much due to the bitter taste.
That bitter taste, caused by alkaloids (a nitrogen-containing substance), is designed to ward off insects and other critters that would otherwise eat the plant. Have you ever noticed that deer won’t eat a tomato plant but will gladly pluck the tomatoes off? That’s why. But plant is protected by the alkaloids. The fruit itself has very little alkaloids in it.
This idea that tomato plants are poisonous has been generalized to all nightshades. And thus, we end up with logic that says, “nightshades are poisonous because they are nightshades” with no more support to the tale than that.
Are nightshades good for you?
The short answer is, “Yes!” Nightshades have a vast variety of nutrients and antioxidants. Plus, they are loaded with fiber. That makes them a great source of nutrition with very few calories.
Is there anyone who shouldn’t eat nightshades?
There have been a few (less than five, none on humans) studies that suggest that people with inflammatory bowel disease (IBD) such as Crohn's disease and ulcerative colitis MAY have their symptoms aggravated by nightshades. Additionally, some people with autoimmune disease such as celiac disease, multiple sclerosis and rheumatoid arthritis have found that their symptoms are reduced when they don’t eat nightshades.
The thought in all of these cases is that the lining of the intestine is already compromised and that the small amount of alkaloids found in these food irritates it further.
How do you figure out if you shouldn’t eat nightshades?
There are some people, particularly those with arthritis, who just seem to feel better when not eating nightshades. To determine if you are someone who feels better not eating them, your best option is to do an elimination diet with A/B testing. Basically, that means you track your symptoms (A). Stop eating nightshades for a period of time to clear your system and track your symptoms (B). And then add them back one at a time while tracking your symptoms (return to A). It can be a bit tedious because you also have to be aware of any foods made with nightshades such as ketchup and pasta sauce.
If you determine you feel better not eating nightshades, it is wise to continue to track your symptoms to eliminate the placebo effect.
Most people are encouraged to eat nightshades for their impressive nutrition content. There are a few animal and test tube studies that suggest a small minority of people with existing health issues might benefit from avoiding some or all nightshades.
To lower the alkaloid content of nightshades, avoid eating green tomatoes, peel your potatoes (so sad since the bulk of the nutrition is in the peel), eat sweet potatoes instead and always thoroughly cook all nightshade veggies.
To discuss how Dr Robyn can help you create and track an elimination diet, please use this link to schedule a free 20-minute discovery call.
Dr Robyn is a former competitive volleyball player turned psychologist with continuing education in nutrition. Russ is a former competitive bodybuilder and trainer on the Mr. Olympia Tour. They are the co-founders of Whole Food Muscle and the authors of How to Feed a Human The Whole Food Muscle Way. To work with them one on one to improve your health and fitness or to have them speak at your event or organization email them at Health@RnRJourney.com.