#141 - AMA #18: Deep dive: sugar and sugar substitutes
Peter Attia, joined by Bob Kaplan, discusses sugar and sugar substitutes, emphasizing the importance of understanding specific sugar molecules over generic terms. The episode covers various forms of sugar, added vs. naturally occurring sugars, and categories of sugar substitutes.
Deep Dive Analysis
6 Topic Outline
Defining the Term 'Sugar' and its Ambiguity
Understanding Monomers: Glucose and Fructose
Metabolic Differences Between Glucose and Fructose
Sucrose: The Disaccharide of Glucose and Fructose
Historical Context and Consumption Trends of High Fructose Corn Syrup
Distinguishing Between Sugars and Added Sugars on Food Labels
6 Key Concepts
Monomers
Monomers are the simplest building blocks of carbohydrates. In the context of sugar, glucose and fructose are key monomers, each having the same chemical formula (C6H12O6) but different structural arrangements (glucose is a six-carbon ring, fructose a five-carbon ring).
Glucose
Glucose is a six-carbon ring monomer, a simple sugar that often results from the breakdown of starches. Its metabolic effects differ significantly from fructose, even with a similar chemical formula.
Fructose
Fructose is a five-carbon ring monomer, often referred to as 'fruit sugar' due to its presence in fruits. Despite having the same chemical formula as glucose, its distinct structure leads to dramatically different metabolic effects, and it does not stimulate insulin secretion in the same way glucose does.
Disaccharide
A disaccharide is formed when two monosaccharides (monomers) are covalently bonded together. Sucrose is a common example, created by combining one molecule of glucose and one molecule of fructose.
Sucrose
Sucrose is a disaccharide made of one glucose molecule and one fructose molecule bonded together. It is commonly known as refined sugar, extracted from sources like sugar cane and beets.
High Fructose Corn Syrup (HFCS)
HFCS is a sweetener made from a solution of glucose and fructose, typically with a 45:55 glucose to fructose ratio, making it slightly sweeter than sucrose. It was developed as an alternative to sugar due to tariffs and new production technology, and its consumption has varied over time.
5 Questions Answered
The term 'sugar' is ambiguous and can refer to many different molecules, including glucose, galactose, fructose, sucrose, and allulose. It's more helpful to think of them through their basic molecular attributes rather than a generic name.
No, glucose and fructose are not the same, even though they share the same chemical formula (C6H12O6). Glucose is a six-carbon ring, while fructose is a five-carbon ring, and this structural difference leads to dramatically different metabolic effects in the body.
Sucrose is a disaccharide formed by the covalent bonding of one molecule of glucose and one molecule of fructose. It is commonly known as refined sugar, extracted from sources like sugar cane and beets.
Historically, HFCS was seen as a healthier alternative, especially for diabetics, because fructose doesn't stimulate insulin secretion like glucose. However, there has been a shift in public perception, with many now viewing sucrose as 'healthier' or 'more natural' than HFCS, which often has a slightly higher fructose content (e.g., 45% glucose, 55% fructose) compared to sucrose's 50/50 split.
A properly adherent food label distinguishes between 'sugars' (total sugars, including naturally occurring ones) and 'added sugars' (sugars that have been added during processing or preparation), providing more detailed information about the sugar content of a product.
6 Actionable Insights
1. Seek Professional Medical Advice
Do not use the podcast’s general information as a substitute for professional medical advice; always seek assistance from healthcare professionals for any medical conditions you have. The podcast content is for informational purposes only and does not constitute medical advice or form a doctor-patient relationship.
2. Think Molecules, Not Names
When considering “sugar” or similar substances, shift your perspective to think about them through the lens of their constituent molecules (e.g., glucose, fructose) rather than generic names. This approach is more helpful because generic terminology is unhelpful and inaccurate, as it lumps together many different molecules with distinct metabolic effects.
3. Check Food Labels for Added Sugars
When examining food labels, specifically look for both “sugars” (total sugars) and “added sugars” listed separately. A properly adherent food label provides this distinction, which is crucial for understanding the sugar content and making informed dietary choices.
4. Consult Lustig & Johnson
To understand the dramatically different metabolic effects of glucose and fructose, listen to podcasts featuring Rob Lustig and Rick Johnson. They do an exceptional job explaining why these molecules, despite similar chemical formulas, have profound metabolic differences.
5. Sweetness Indicates Fructose
As a general rule, use the level of sweetness in a food as an indicator: the sweeter it is, the more fructose it likely contains. This can help in making informed food choices, given fructose’s distinct metabolic effects.
6. Natural Sugars: Glucose & Fructose
Understand that naturally sweet foods like apples, honey, and mangoes contain a balance of both glucose and fructose. This clarifies the molecular composition of “natural” sugars and helps avoid misconceptions.
3 Key Quotes
The reason I'm frustrated by this terminology is it means a lot of different things. And all of those things can be true. Glucose is a sugar. Galactose is a sugar. Fructose is a sugar. Sucrose is a sugar. As you mentioned, allulose is a sugar. Now to lump all of those things in one category is unhelpful.
Peter Attia
That to me is one of just the coolest things about biology and biochemistry specifically is even the minorest tweak can have a profound difference.
Peter Attia
When people use the word sugar, I think the first thing that jumps to mind is probably something that is technically referred to as sucrose.
Peter Attia