Hello, I'm Monica Reinagle, and you're listening to The Nutrition Diva Podcast, a show where we take a closer look at dietary fads and dubious claims so that you can make more informed decisions about your own health and nutrition.

Over the years, I have looked at a whole slew of dietary fads that could be grouped together under the general heading of personalized nutrition.

There was the blood type diet, for example, which claimed that you should either include or avoid various categories of food based on whether you had type O, A, B, or A, B blood.

A different dietary pattern was recommended for each blood type. And, you know, at any one of them would constitute a substantial nutritional upgrade compared to the typical American diet.

But there's very little research to support any connection between one's blood type and one's ideal diet.

There were also popular diets based on body shape, one diet for those with pear-shaped figures, another for those with apple-shaped bodies, and so on.

And as with the blood type diets, following any one of them would result in a much healthier diet than most people were already eating.

But again, the science supporting different diets for different body shapes was speculative at best.

Another whole category of personalized nutrition involves testing your blood for the presence of antibodies, which would allegedly reveal subtle food sensitivities that were responsible for your symptoms or for your inability to lose weight,

except that these tests are not considered valid indicators of an actual food sensitivity.

Now, to be clear, food tolerances do exist. It's just that these sorts of tests are not a reliable way to identify them.

There's a very high rate of false positives, where the test says that you're sensitive to a food that you actually tolerate just fine.

And as a result, they usually result in overly and unnecessarily restrictive diets.

But the appetite for personalized nutrition continues unabated.

And more recently, advances in genomics and microbiomics have led to an explosion of new products and services that claim to give you a personalized dietary prescription based on an analysis of your microbiome.

Or your DNA. And I get it. It's long been clear that we don't all respond the same way to the same dietary interventions.

Some people do really well on a higher fat diet. Others develop high triglycerides or cholesterol on that same diet.

Some people lose more weight when they reduce carbs. And other people lose more weight when they increase complex carbs and reduce fat.

So if those differences were genetic, maybe we could skip some of the trial and error and just zero right in on the best approach for each unique individual based on their DNA.

Several large studies were launched to validate this approach and several large companies were launched to monetize it.

The studies, unfortunately, have been less than convincing. The monetization of DNA based diets, however, continues a pace.

And here's the crazy thing. Even though the science does not really support them, these personalized dietary prescriptions

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