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DIY endurance fueling ingredient

Dextrose (glucose monohydrate)

Dextrose is pure glucose in powder form — the fastest-absorbed carbohydrate available, useful as a small accelerator but a poor base for a full bottle because it loads the drink with osmolarity.

What it is, and how to use it

Dextrose is anhydrous or monohydrate glucose, the same molecule the body uses for cellular fuel. Absorption is essentially limited only by gastric emptying — there is no breakdown step at all in the gut.

For DIY fueling, dextrose is best thought of as a small accelerator rather than a bulk base. Two reasons. First, osmolarity is high: 5.55 mOsm per gram of carb. A 10% w/v dextrose solution is already noticeably hypertonic, which can slow gastric emptying and cause GI distress on the bike. Second, the gut's main glucose transporter SGLT1 saturates around 60 g/h; above that, you need fructose alongside, and dextrose alone can't get you to 90+ g/h.

Practical places to use it: as the glucose half of a glucose:fructose mix where you want a pure, sweetness-controlled blend (dextrose is ~74% as sweet as sucrose); in a small concentrate flask paired with a moderate amount of fructose; or as a quick pre-session top-up (50–80 g in water 30 min before the start).

Avoid using dextrose as the only carb in a long sip bottle — replace bulk volume with maltodextrin instead. German bulk price: €3–4/kg from sports-nutrition suppliers.

Composition

Total carbs
100 % by weight
Glucose
100 % of carb mass
Fructose
0 % of carb mass
Other carbs
0 % of carb mass
Sweetness factor
0.74 × 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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