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DIY endurance fueling ingredient

Pure fructose powder

Pure fructose is the secret weapon for high carb-rate endurance fueling — its separate GLUT5 transporter lets you stack another 30–50 g/h on top of glucose's ~60 g/h ceiling.

What it is, and how to use it

Fructose is the simple sugar found in fruit. In DIY endurance fueling it is the dose-extender: glucose alone saturates at roughly 60 g/h because the SGLT1 transporter caps absorption there, but fructose uses a completely separate transporter (GLUT5) and adds another 30–50 g/h of usable carbohydrate per hour.

Three rules of thumb. Below 60 g/h, you can ignore fructose entirely. Between 60 and 90 g/h, aim for a glucose:fructose ratio around 2:1. Above 90 g/h, move toward 1:0.8 (Hearris et al., 2022).

Sweetness is high (≈1.7× sucrose), so pure fructose mixes taste noticeably sweet. Most athletes prefer to source the fructose via sucrose (table sugar) or honey if they don't already have a low-sweetness base like maltodextrin. Osmolarity matches glucose at 5.55 mOsm/g, so don't try to deliver all your fructose through a single fructose-only bottle — it will be too dense.

GI tolerance to fructose is highly individual and trainable. Athletes new to high-fructose fueling should start at 2:1 (glucose-heavy) and shift over weeks. Sudden 1:0.8 jumps cause notable GI distress in roughly a third of untrained guts. German bulk price: €6–8/kg from sports-nutrition retailers.

Composition

Total carbs
100 % by weight
Glucose
0 % of carb mass
Fructose
100 % of carb mass
Other carbs
0 % of carb mass
Sweetness factor
1.73 × sucrose
Osmolarity
5.55 mOsm / g carb

Exact values — derived from chemistry, not a producer average.

Try this ingredient in the DIY endurance fueling calculator.

Sources & citations

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