Tag Archives: tomatoes

What Are Nightshades, and Should I Avoid Them?

Rosemary Chicken (garnished with pico de gallo) and Rosemary Potatoes

Rosemary Chicken (garnished with pico de gallo) and Rosemary Potatoes

The nightshade family includes tomatoes, peppers, potatoes (not sweet potatoes or yams), eggplant, goji berries, and even tobacco.  Anecdotal reports indicate that consumption of these either cause or aggravate certain chronic medical conditions, such as arthritis, chronic fatigue, or irritable bowel syndrome.

Georgia Ede, M.D., has an article on medical effects of nightshades at her website.  The potentially offensive chemicals in nightshades are called glycoalkaloids.  I looked into this issue when deciding whether to include potatoes in my version of the paleo diet.  (They’re included).

Dr. Ede’s writes:

As with any food sensitivity, the only way to find out is to remove nightshades from your diet for a couple of weeks or so to see if you feel better.  There are ZERO scientific articles about nightshade sensitivity, chronic pain, or arthritis in the literature, however, the internet is full of anecdotal reports of people who have found that nightshades aggravate arthritis, fibromyalgia, or other chronic pain syndromes.

I bet I could eat a couple potatoes and tomatoes every day without ill effect.  And there’s Chris Voigt, head of the Washington State Potato Commission, famous for his 60-day potato diet.  As they say, your mileage may vary.

Some of the nightshades, such as potatoes, supply a major carbohydrate load that can spike blood sugars too high in many diabetics. Be careful. And  use your home glucose monitor.

Steve Parker, M.D.

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What’s Dr. Bernstein Got Against Tomatoes?

Eat greens for vitamin K

Looks reasonable to me

Dr. Richard Bernstein cautions his diabetic patients and readers of Diabetes Solution to keep a tight lid on consumption of tomatoes.  An excerpt from page 149:

If you have them uncooked in salad, limit yourself to one slice or a single cherry tomato per cup of salad.

His concern is that tomatoes will raise your blood sugar too high.

That doesn’t make sense to me.  A 3-inch diameter tomato has 7 grams of carbohydrate, 2 of which are fiber.  So the digestible carb count is only 5 grams.  That’s not much.  So do tomatoes have a high glycemic index?  Unlikely, although it’s hard to be sure.  Good luck finding a reliable GI for tomatoes on the Internet.

I think Dr. Bernstein’s wrong about this one, which is rare.  I suppose it’s possible that tomatoes deliver some other substance to the bloodstream that interferes with carbohydrate metabolism, but Dr. Bernstein doesn’t mention that.

Do tomatoes play havoc with your blood sugars?

Steve Parker, M.D.

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Filed under Carbohydrate, Vegetables