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Dangers of 3 Surprising Health Superfoods – Dr. Michael Greger


If you’re wondering whether superfoods are worth it or not, you may want to read on.

Many of us may be buying into the idea that we need certain superfoods to be at our optimal health. However, our interviewee today presents a controversial perspective on certain foods, one that many in the health and wellness industry may not necessarily agree with.

For instance, he continues to encourage people to avoid spirulina (and blue-green algae) products given toxins found in spirulina supplements.

Today, we’re back with Dr. Michael Greger, Founder of, again to discuss:

  • Why kombucha maybe associated with life threatening lactic acidosis
  • Why kimchi maybe related to cancer
  • Why you may want to think twice before consuming spirulina
  • If you should avoid night shades like eggplants in your diet
  • Why Dr. Greger advocates soy, and why soy maybe beneficial for breast cancer survivors

This is the 5th part of the interview series. For the last part of the interview as well as the podcast and video with Dr. Greger, please stay tuned HERE.

3 “Superfoods” you should be wary of?

Q: You recommend against eating “superfoods” such as spirulina, kombucha, and kimchi. Why is that? What are other health foods should we be aware of?

Dr. Michael Greger:  Well, all 3 have been associated with adverse effects, now some of these are rare.

#1: Kombucha

Take kombucha as an example. There are a just a few case reports of this life threatening lactic acidosis, or basically your body gets so acidic you fall into a coma and die if you don’t get rapid therapy. It happens rarely, but why not eat something that doesn’t happen at all? It’s like there is no lactic acidosis comas from broccoli ever. No one ever reported, so I’ll stick to it.

Unless there was something that you couldn’t find anywhere else, then maybe you take the risk. But otherwise why do it?

#2: Spirulina and Blue-Green Algae


Both spirulina and blue-green algae can have neurotoxins, nerve toxic contaminants.

#3: Kimchi


Kimchi is interesting. You’d think kimchi would be rather healthy. This is what? Cabbage, garlic. But Korean researchers found people that eat kimchi have higher rates of certain cancers. The question is why?

We are not sure, it may be because of the inflammatory effect. What we would assume to be healthy, these probiotic in lactobacillus, it’s possible that even when cooked dead they could kind of trigger an inflammation, get these so called endotoxins which are part of bacterial cell walls, could under some circumstances get absorbed into the system and trigger this inflammation.

The body is thinking “Oh, bacteria.” We really don’t know. But until studies started showing that kimichi is associated with less cancer or at least no more cancer, they are just not good to eat.

Q: Great, are there any other health foods we should be aware of that you have not published?

Dr. Michael Greger:  I did something on star fruit; it was a little high in oxalic acid. What else? There’s a bunch of supplements that have adverse effects.

In terms of whole plant foods, very few I can think of .

Nightshades, anyone?

Q: What about night shades like eggplants? What are your thoughts on that?


Dr. Michael Greger: Yeah, we’ve got 1 in 20 people with joint pains improve when removing the night shades from their diet. So tomatoes, eggplant, bell peppers.

But for the other 19 out of 20, it doesn’t do anything for them.

So, for the vast of the majority of people night shades are fine. But look if not eating night shades makes you feel better, don’t eat night shades.

I mean no doctor can tell you more than your own body can tell you. It was like gluten issue.

There are rare individuals who have gluten problems and for them, stay away from gluten. But that doesn’t mean gluten is bad for everybody.

Someone has a peanut allergy and they die from eating peanuts. It doesn’t mean everybody dies from eating peanuts.

Soy Increases Longevity?


Q: You do advocate soy in your videos. Now, what about authorities that associate soy with diseases like infertility, breast cancer? Can you elaborate on that and your take on that?

Dr. Michael Greger: Well, I would certainly question the title of authority. There’s contradictory laboratory animal data, on breast cancer and soy up to 2009. So, it depends on whether it was a hamster or rat.

We had no idea until 2009 when the first human study finally had cancer survivors split up into two groups: half eat soy, half didn’t, and what happened?

What happened was that the women that ate soy lived longer, had lower relapse rates. So, soy is beneficial for breast cancer survivors.

There have been a total of four such studies based on breast cancer survivors today.

Starting 2009 and every single one four out of four, show, if anything, benefits. And so, that’s it. There have only been four studies, and they’ve all shown the same thing.

So, anyone who suggests that soy is bad for breast cancer is either living before 2009, hasn’t checked the literature in the last five years, or don’t believe the scientific method or who knows?

But it’s not even the balance of science, that’s all the science we have all points in one direction with breast cancer.

Q: Now, what about commercially produced GMO soy, is your view going to be different?

Dr. Michael Greger: Almost all GMO soy is just animal feed. And that’s where GMO soy and corn go is to feed livestock.

But there if you don’t want to get GMO, you should buy organic. So, organic soy by definition by 2002 USDA organic standards can’t have any GMOs.

About Dr. Michael Greger: Dr. Michael Greger is an internationally renowned physician specialising in clinical nutrition, author, and globally recognised professional speaker on on various public health issues.  Dr. Greger’s work can be found at