How Elevated Blood Sugar Affects the Brain and Heart

Chris Williamson: Lots of people that listen to the podcast will probably have a good indication of, well, where's my body weight at? And I probably go to the gym and I do all the rest of this stuff. What else is happening? How else can I motivate myself to pick the healthier option, even if I know that my waistline isn't going to be the determining factor for this? I'm not— obesity isn't that much of a risk for me. So what is it that could be happening?

Dr. Rhonda Patrick: So I think it's interesting to sort of break it apart like that. I guess another area that I'm particularly interested in is brain health and energy levels when it comes to the impact of the ultra-processed foods, the added sugar, stuff like that. And that's probably one of the biggest areas that it also has an impact on.

So if you're eating a lot of added sugar, then you can have higher than— you can basically be on the high end of the normal range for blood glucose levels. So you're within the normal range, but on the higher end, right? So you're not diabetic, so you might think, oh, I don't have diabetes, I'm fine, I'm still within the normal range. But there are studies showing that people on the high end of the normal range have increased atrophy in the hippocampus part of their brain that's involved in learning and memory, and they have higher atrophy in the amygdala part of their brain that's involved in emotional regulation compared to people on the lower end, have, you know, blood glucose levels in the, the lower end of the normal range.

Chris Williamson: Hmm. So

Dr. Rhonda Patrick: That's an association study, right?

Chris Williamson: There's also— angry and forgetful.

Dr. Rhonda Patrick: Right. But, again, it's association study. There's also other studies showing that higher blood glucose levels are associated with increased, like 54% risk, increased risk for vascular dementia. So, glucose, what it's doing when you have a constant intake of glucose and that glucose, let's say you're not exercising enough to have that glucose get disposed into your muscle, which is really where you want it, right? You want it to get taken up into your muscle. Exercise really helps with that. So, when you exercise, you cause a lot of glucose transporters to come up to your muscle, which opens up the gates to allow glucose in. You want it to go to your muscle instead of your adipose tissue.

If that doesn't happen, if you're not exercising enough, the glucose will stay around in your bloodstream. And what happens is, yes, there's an insulin response and all that metabolic stuff. But there's also something that happens that's called the Maillard reaction, and it's where glucose reacts with lipids, it reacts with DNA in your body, it reacts with proteins and damages them. And when it reacts with proteins, like for example, collagen lining your pericardium surrounding your heart, your myocardium surrounding your heart, lining your blood vessels, it causes the collagen to become stiff. It changes the properties of the protein. It makes them stiff, kind of like trans fats. Actually, that's a really good analogy. I didn't think about that, but it's really kind of a similar thing.

It causes your blood vessels to become stiff. It causes your, the tissue surrounding your heart to become stiff. And that plays a major role in the stiffening of the heart with age, which affects, you know, it affects cardiovascular disease risk, right? So, you're talking about just an accumulation of these, this Maillard reaction. What happens is it forms something called advanced glycation end products, and that's what is basically stiffening the proteins like collagen, which are around forever. You don't, your collagen surrounding your heart and it's there and, you know, you don't wanna make it stiffer, right? So, that's something to consider as well as the fact that it is affecting cognition and the brain.

Chris Williamson: Mm-hmm.

Dr. Rhonda Patrick: As well. So, we talked about brain aging, it causes inflammation.

So, for example, I mentioned the study of men that consumed the sort of 20-ounce sugar-sweetened beverage and they had 100% increase in their inflammatory markers after 3 weeks. Well, inflammation essentially is those molecules are getting into the brain, crossing over the blood-brain barrier, and they're getting into the brain. It was thought for a long time that inflammatory molecules don't cross the blood-brain barrier, but that years ago was debunked. We now know a lot of cytokines and inflammatory things are crossing the blood-brain barrier. And when they get into the brain, They are doing a variety of things. For one, they're affecting mood immediately. And, we know that for a fact. We know causally.

You can take a healthy person and inject them with lipopolysaccharide, which is something that's found in our gut. It's a component of bacterial membranes. So, we have a lot of bacteria in our gut that makes up our microbiome. When you have leaky gut, intestinal permeability, lipopolysaccharide gets into your circulation. Refined sugar does do that. You can inject normal healthy people with lipopolysaccharide or placebo, which is saline, and it causes massive inflammation, okay? Like what I just talked about with a sugar-sweetened beverage. And, those people then end up getting depressive symptoms. So, it plays a role in their mood.

But, if you blunt that inflammatory response with something like EPA, which is a component of omega-3, it's one of the omega-3 fatty acids, it doesn't cause the depressive mood. So inflammation does affect mood. We also know that when you have a high inflammatory state, which I just gave a lot of evidence for in terms of added sugar, it changes the metabolism of tryptophan. Tryptophan is an essential amino acid we get from our diet. It's in proteins. It's a precursor for serotonin. Serotonin is a neurotransmitter that's involved in cognition, executive function. It's involved in mood. What inflammation does is it causes tryptophan, instead of being converted into serotonin, it causes it to be converted into something called kynurenine, which is involved in inflammation.

It's basically your body's going, oh, I'm inflamed. I've got a pathogen. Okay, there's no pathogen. It's actually just added sugar, too much added sugar, right? Constantly. And so, your body thinks it's a pathogen. And so, it's trying to then make anything it can to activate immune cells to take care of the pathogen, right? But the problem is, is that it's not a pathogen. So, kynurenine helps with that whole activating the immune system, but also what it does is, as it's metabolized, it can form something called quinolinic acid, which is a neurotoxin, and it's also associated with depression. So, you're talking about inflammation now affecting, you know, key metabolic processes that are important for cognition, executive function, mood.

Chris Williamson: Yeah.

Dr. Rhonda Patrick: And dampening those processes, right?

So you can immediately have an effect on cognition. I mean, you get like a quick sugar high, but boy, does that go away pretty quick, right? I mean, it's like you immediately start to feel like that sort of—

Chris Williamson: Yeah, if you wanted to reliably make your mental performance bad, having a donut and a Coke an hour before you were supposed to do something important is probably a pretty good way to do it.

Dr. Rhonda Patrick: Exactly. It's almost like when you're sick, how you feel, right? You feel foggy, brain foggy, because your inflammation, your immune system's activated.