QUESTION: “Greetings Dr. Neal, I have subscribed to your podcast for over a year and have learned so much and was hoping you could answer the following question on The Blood Type Diet. The last thing I saw documented about this diet was in 2017 and that the diets proposed for each blood type would be a good choice no matter what blood type you have, but I wanted to know if there was any recent research to determine if dieting based on blood type has any real science behind this approach? Or is it just another fad diet?”
DR. NEAL: Thank you for your question. And, thank you so much for your kind words and for subscribing to the show. I appreciate you.
So, here’s the deal with the Blood Type Diet: it’s a fad. It is interesting that we haven’t heard anything about it recently.
As you mentioned, research examining whether this diet improves health has basically stopped. That was actually my first clue that this was likely a passing fad.
What’s The Blood Type Diet About, Anyway?
The Blood Type Diet seemed like a promising idea on the surface. Studies looking at blood type and disease risk found that certain conditions are associated with a person’s blood type. So, it seemed natural that blood type may also influence how we absorb and metabolize foods.
In 1996 and 2004, books were published claiming that our blood contained clues from our ancestors – clues that could help us live a healthier life. And, by following a diet for your specific blood type, you are eating as your ancestors would have. And, by knowing which diseases are more common in those with specific blood types, you can reduce your risk for developing diseases (like cardiovascular disease and cancer), while at the same time, helping you feel more energetic.
Here's an example: the author of the blood type diet book claimed that those with type B blood would benefit from consuming dairy products. Why? Because it is believed that this blood type came from those that are descendants of nomadic tribes. And, nomadic tribes would have bred livestock and therefore relied on their milk for survival.
Again, interesting idea, but does the science support this theory? Sadly, no.
When we look carefully at the diets for each blood type, they all have something very interesting in common: they’re mostly plant-based and they discourage the consumption of highly processed foods. There’s plenty of scientific evidence showing the health benefits of following a plant-based diet.
So, here’s the question we need to ask: is eating according to your blood type potentially helpful? Or, is that swapping out burgers and fries for kale and quinoa is helping people feel better and reducing their risk for disease?
Well, there were 4 published studies examining the effects of following the blood type diet and they were poorly designed. Interestingly, one published study was conducted by someone that was about to write a book on the benefits of a blood type diet. Conflict of interest much?
Another study found that in some folks, they felt worse after following the blood type diet – their food allergy symptoms flared up. Even so, I always like to look at meta-analyses – this is where researchers look at a bunch of published studies all at once before making conclusions.
One of the most cited meta-analysis concluded… ready for it?
“There is currently no evidence that an adherence to blood type diets will provide health benefits.”
The authors of this meta-analysis go on to provide a word of caution. They say that any claims about the health benefits of blood type diets are not supported by scientific evidence.
Pretty strong words.
What To Do?
So, again, until more studies are conducted, we can confidently say that a blood type diet is a fad.
It’s possible that if someone follows this diet and begins to see positive health benefits, it may simply be because they have begun to eat more nutritious foods. They may have swapped out highly processed foods for plant-based foods which is why they feel better. And, don’t get me wrong, this is fantastic.
But, it’s likely misleading to give credit to the blood type for this.
Because, again, any claims about the health benefits of blood type diets are not supported by scientific evidence.