Skip to main content

DIY endurance fueling ingredient

Brown rice syrup

Brown rice syrup is the secret of high-strength carrier flasks — mostly maltose and maltotriose, almost no fructose, with the lowest osmolarity of any common DIY ingredient.

What it is, and how to use it

Brown rice syrup is produced by treating cooked rice with malting enzymes that cleave the starch into shorter chains. The result is a thick syrup of roughly 45% maltose (two glucose units), 30% maltotriose (three glucose units), 20% higher-DP oligosaccharides, and 3–5% free glucose. There is essentially no fructose.

Two properties make rice syrup interesting. First, very low osmolarity per gram of carb (~1.8 mOsm/g) because most of the mass is bound in disaccharides and trisaccharides — lower than maltodextrin, and dramatically lower than pure sugar. You can mix 18–22% w/v rice syrup solutions without crossing into the hypertonic territory that triggers GI distress. Second, mild sweetness (~50% of sucrose) means high concentrations are still drinkable.

Best place to use rice syrup in a DIY plan: the concentrate soft flask. A 150 ml flask at 22% w/v carries ~33 g of carbohydrate, sipped over the back half of a long session. Pair it with a separate fructose source (table sugar, honey, or pure fructose) in your main sip bottle so the overall ratio still falls into the 2:1 or 1:0.8 range.

Cost: €5–8/kg from German health-food stores and Amazon DE.

Composition

Total carbs
75 % by weight
Glucose
3 % of carb mass
Fructose
0 % of carb mass
Other carbs
97 % of carb mass
Sweetness factor
0.50 × sucrose
Osmolarity
1.80 mOsm / g carb

Typical values; expect ±10% variance between producers / lots.

Try this ingredient in the DIY endurance fueling calculator.

Sources & citations

Other DIY fueling ingredients

← back to all ingredients