Skip to content
Home » Fix The Microbiome: #1 WORST Food For Human Gut Health: Mary Ruddick (Transcript)

Fix The Microbiome: #1 WORST Food For Human Gut Health: Mary Ruddick (Transcript)

Read the full transcript of health expert specializing in gut health and the microbiome Mary Ruddick in conversation with Rina Ahluwalia of The Primal Podcast on “Fix The Microbiome: #1 WORST Food For Human Gut Health”, August 2, 2025.

The Hidden Dangers of “Healthy” Foods: A Conversation with Mary Ruddick

RINA AHLUWALIA: If you’re dealing with some chronic issues, it could be things like pain, arthritis, inflammation, weight gain, even hormonal issues like thyroid issues. Chances are it starts in your gut. And the conventional advice about just take some fiber, take some probiotics, or just start a healthy diet, in most cases, this can make it worse.

My guest today, Mary Ruddick, is an ancestral nutritionist and she has spent time studying the world’s healthiest disease free communities. She’s traveled to the Hadza in East Africa and also studied the longest living elders in Sardinia. And she knows what modern medicine has missed. She knows what is ruining your gut and killing the gut microbiome, including the worst food in the world for human gut health.

So, Mary, my first question. What are the healthy foods that people are eating every day that is causing gut problems and inflammation?

MARY RUDDICK: Nightshades. I would say the nightshades. Everything from potato, tomato, eggplant, bell pepper, all of those.

RINA AHLUWALIA: And why are nightshades, what is it in those potatoes, bell peppers, that is so bad for the gut and so bad for our bodies?

The Problem with Nightshades

MARY RUDDICK: I think anything that we don’t feel immediately that’s a toxin is a problem. Right? So arsenic or the issues that we had with the green wallpaper and fabric in the 1800s. When we don’t feel the toxin, we assume everything is fine.

But the issue with the nightshades is that they have the lectin, which you can neutralize. That one can be neutralized, but that if it’s not neutralized, it sticks. It’s a sticky protein and it damages both the gut and the nervous. Well, actually not both, all three and the immune system, all the areas we’re having trouble with. So that’s not great. Right. But traditional societies, if they ate nightshades at all, very few did they had ways of neutralizing that.

The bigger issue is the solanine and the glycoalkaloids. These are fat soluble toxins that bind that lectin and keep that damage going for months on end. So it’s not something that if you just stop, you’re going to feel better tomorrow. You’re going to have to wait a long time to see if you feel better. And it’s not individual, it’s species based. These are not foods that are meant for humans.

The Spinach Problem

RINA AHLUWALIA: So this is the thing that when I speak to a lot of people in my carnivore community, so I do have a carnivore community, it’s full of people wanting to do carnivore or even the ketogenic keto diet. There are so many people that eat these problematic foods. You mentioned potatoes. And it leads to so many different chronic conditions.

But there’s also other problems and other problematic foods. I have some here, spinach, that is also a very healthy food that people eat, but it contains a lot of toxins. What’s bad about spinach?

MARY RUDDICK: Well, I would say that it’s not healthy. That’s. Let’s start there. Because most of what we’ve been told is healthy and not healthy was really not based in science or in history. So when I was being raised, I’m 43. So when I was being raised, spinach salad was the rage. And if you ate a spinach salad, it was like you got a gold star. And then it moved to the spinach smoothies, and I still see those today.

The issue with spinach is not that humans can’t ever eat it, it’s that it’s a very short season. It has a lot of toxins in it, plant toxins that are meant to keep humans and other mammals from eating it. And the bigger issue is that we really require very specific microbes in our microbiome to even handle small amounts of spinach, the oxalates.

And most people today are not born with those. Our C section rates are through the roof. Our antibiotics. I actually just. I screen microbiomes daily, and I finally found one person who actually had the right microbe for it. But it’s so rare these days because you have to get it from your mother. It’s not something you can get from ferments or soil. But I told her, I was like, “you should sell your stool to those FMT places because that’s worth a lot of money.”

But even those little guys, one main species is Oxalobacter bacteria that breaks down the spinach oxalates. But if you overfeed them, they combust. They actually combust. And so then you don’t have them anymore. And let me give you a parameter for that.

So a cup of spinach on average has about 700 milligrams of oxalate. Oxalate are these little crystals. Right. We hear about them a lot in the carnivore community. But outside of the carnivore and the very ill communities where they’re trying to heal themselves, general public still doesn’t really know what an oxalate is. So they’re these little shards of glass.

And unlike solanines, the human body can break down some of them the only 50 milligrams. So if you’re having one cup of spinach and you’re doing that daily, you’re. Even if you were born with that microbe, it’s no longer living. It over ate and exploded.

The White Rice Issue

RINA AHLUWALIA: Absolutely. There’s other oxalates as well. I do want to talk about the plant toxins in categories so that people can understand what that means. But still going back with the healthy foods that people are eating, that’s causing the gut problem. So potatoes is one, spinach is another.