what sugar does to collagen, which is the part that annoyed me most

I learned what glycation was and then, within about a week, started reading the backs of collagen drinks. Some of them hold 15 grams of added sugar.

Once you understand the chemistry, that combination is genuinely irritating.

glycation, in plain language

Glycation is sugar molecules attaching themselves to proteins without an enzyme directing the process. It is not controlled, it is not useful, and it happens quietly whenever sugar is circulating.

The end result is a class of compounds called advanced glycation end products, which have the unfortunately perfect acronym AGEs.

Gkogkolou and Böhm's review in Dermato-Endocrinology lays out why skin is so vulnerable. AGEs form on long lived proteins, and the longest lived structural protein in your body is collagen. Some of the collagen in your skin has been there for years.

what it actually does down there

Glycation cross links collagen fibres to each other. Cross linked collagen is stiffer, less elastic, and harder for your body to break down and replace.

That last part is the one that got me. Glycated collagen resists the normal turnover process, so it accumulates. You end up with a growing share of your dermal matrix made of fibres that no longer do the job properly and will not clear out.

Danby's paper in Clinics in Dermatology is the standard reference on this in the skin context, and the mechanism is well accepted rather than fringe.

so a sugary collagen drink is arguing with itself

You are supplying material to build new collagen while supplying the sugar that stiffens the collagen you already have.

I am not going to claim one sweet drink undoes a day of good habits, because that is not how any of this works and the effect is cumulative and slow. But if the reason you bought the drink is the collagen, loading it with sugar is a strange way to spend those calories.

what we did instead

One gram of total sugar per can, and none of it added. What is there comes from organic fruit juice used for flavour, mainly peach and a little lemon.

Sweetness comes from organic monk fruit extract, which is not metabolised as sugar and does not raise blood glucose. There is a separate piece on this blog about why we chose that over sucralose, stevia, or erythritol, and the erythritol reasoning in particular is worth reading.

Ninety calories a can, 20 grams of collagen protein, one gram of sugar.

the wider version of this

Glycation is not really a collagen drink problem. It is a diet problem, and everything that steadies your blood sugar helps, including protein with meals, fibre, and walking after eating.

What I will say is that a collagen product should at minimum not be part of the problem. Turn the can around and find the sugar line. It takes four seconds and it tells you whether the product is on your side.

the research i leaned on

• Gkogkolou P, Böhm M. Advanced glycation end products: key players in skin aging? Dermato-Endocrinology. 2012;4(3):259-270.
• Danby FW. Nutrition and aging skin: sugar and glycation. Clinics in Dermatology. 2010;28(4):409-411.

LÉS is a beverage, not medicine, and nothing here is medical advice.