1/6) How Fructose Hijacks the Liver to Fuel Cancer (Link in 6/6)...
Nick Norwitz MD PhD@nicknorwitz
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Oct 16, 2025
~2 min read
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1/6) How Fructose Hijacks the Liver to Fuel Cancer (Link in 6/6)
Quote: “In all cases, diets supplemented with high-fructose corn syrup resulted in faster tumor growth compared with control diets.”
This includes melanoma, breast, and cervical cancers. What’s going on is ‘sneakier’ than you might think? Let’s break it down 🧵👇
Quote: “In all cases, diets supplemented with high-fructose corn syrup resulted in faster tumor growth compared with control diets.”
This includes melanoma, breast, and cervical cancers. What’s going on is ‘sneakier’ than you might think? Let’s break it down 🧵👇
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2/6) Cancer is a master hijacker. In this case, it co-opts the liver. When the liver gets fructose, it turns it into molecules that cancer cells repurpose into specific phosphatidylcholines—key building blocks for cell membranes.
Fructose → liver → raw materials for cancer’s construction project.
Fructose → liver → raw materials for cancer’s construction project.
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3/6) But this isn’t just about fructose—it’s about how molecules we eat aren’t passive.
And, it’s why I can’t stand the phrase “empty calories.”
That phrase implies calorie-containing molecules (e.g. fructose) are neutral unless they come with nutrients. But that’s empty thinking. Here’s why...
And, it’s why I can’t stand the phrase “empty calories.”
That phrase implies calorie-containing molecules (e.g. fructose) are neutral unless they come with nutrients. But that’s empty thinking. Here’s why...
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4/6) “Empty calories” implies that calorie-containing molecules are just an energy-containing vehicle for other bioactive and signaling molecules.
But fructose isn’t just fuel—it signals the body. It gets redirected, reshaped, and used in ways that affect health at the molecular level.
Energy-providing molecules are information. They tell your body what to do. And in this case, fructose is telling cancer how to grow.
But fructose isn’t just fuel—it signals the body. It gets redirected, reshaped, and used in ways that affect health at the molecular level.
Energy-providing molecules are information. They tell your body what to do. And in this case, fructose is telling cancer how to grow.
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5/6) As just a small nuance nibble and example, the enzyme that processes fructose – KHK - is unusual because it lacks normal ‘negative feedback’—the built-in off switch most enzymes have to keep their activity under control.
Without this brake, fructose metabolism can run unchecked, leading to calorie-independent harms including mitochondrial damage and signaling for de novo lipogenesis.
Now, to have these harms, fructose does need to end up in the wrong cells (e.g. hepatocytes/liver cells). And how it does so, or whether the body can defend itself first, is a whole separate question…
Without this brake, fructose metabolism can run unchecked, leading to calorie-independent harms including mitochondrial damage and signaling for de novo lipogenesis.
Now, to have these harms, fructose does need to end up in the wrong cells (e.g. hepatocytes/liver cells). And how it does so, or whether the body can defend itself first, is a whole separate question…
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6/6) In the rest of this letter, linked below, we’ll discuss:
🍌Fruit vs Fructose: A clear explanation for why fruit doesn’t equal fructose.
🎯Why Context is King: How your personal metabolic context changes the fructose equation.
🤔What I Do & What I Suggest You Do: My personal strategy, and my specific suggestions for prioritizing foods to gain a metabolic advantage.
🔗staycuriousmetabolism.substack.com/p/fructose-and…
🍌Fruit vs Fructose: A clear explanation for why fruit doesn’t equal fructose.
🎯Why Context is King: How your personal metabolic context changes the fructose equation.
🤔What I Do & What I Suggest You Do: My personal strategy, and my specific suggestions for prioritizing foods to gain a metabolic advantage.
🔗staycuriousmetabolism.substack.com/p/fructose-and…