I just read two different books in this last week that talked at length about tomatoes. One book argued that tomatoes were among the main sources of chronic disease in the modern world. It went on to blame their danger on lectins, found especially in their seeds and skin. The author claimed that if you were to ever deign to eat a tomato, you’d want it to be a roma tomato with no skin or seeds.
The other book talked about how tomatoes were among the richest dietary sources of lycopene. Diets high in this phytonutrient have been shown to protect skin against sun damage, lower the risk of prostate cancer, and reduce the risk of strokes.
Here’s the kicker – because lycopene is primarily found in the skins and seeds of tomatoes, cherry tomatoes are your best source because they have the most skin and seeds per serving.
Is that madness or what? I wish I was creative enough to make this stuff up.
So who’s right?
The answer won’t come from which book has sold the most or who is the biggest perceived authority, the answer comes from the evidence.
In the case of lectins, the author argues that since raw red kidney beans have a lectin that can cause symptoms that mimic food poisoning, all foods with lectins must be able to damage the intestinal tract.
What is the level of evidence cited? That would be a hypothesis. For more detail, if you search for peer-reviewed published studies on lectins and human health, you’ll find thousands of papers. Lectins are involved in scores of immune reactions.
However if you look for studies on how food lectins affect people, you’ll be sadly disappointed. There really are none.
It’s also a bit of a problem to this theory that lectins are found in all foods whether they are plants or animals. They’re also normally found in the human body. We can no more have a problem with lectins as a category, then we could have with food as a category.
To implicate lectins as a health hazard because of the possible effects of consuming a food raw that is never eaten raw, is like implicating spinach as a bad food because of possible food poisoning when it is not handled correctly.
About the lycopene info? Will the author that will accept cited several studies one of the larger of which was a review of 7 other studies looking at over a hundred thousand people and their health risk extending over several decades. In terms of level of evidence this would be an observational cohort study, which trumps hypothesis every time.
It actually came from a really good book that hasn’t gotten the attention it deserves in America despite being very popular in the UK. One of you told me about it last week and I listened to your advice and downloaded it immediately.
It’s called How to Eat Better: How to Shop, Store and Cook to Make any Food a Superfood by James Wong.
James is an ethnobotanist with detailed information on how to maximize your intake of the best phytonutrients with everyday foods. I especially love his book because he opened it with a discussion of levels of evidence in terms of evaluating competing claims like those about tomatoes. I’ve learned a lot of great tips from it already and I’m eager to finish the rest of it.
It bothers me that topic as important as what to eat is surrounded with so much unnecessary controversy. The answers do exist and they’re not hard to find.
In the meantime, be well and please enjoy your tomatoes!
To Your Health,