Also known as: fruit sugar, crystalline fructose, levulose
Fructose
·By Croix
What is fructose?
Fructose is a simple monosaccharide chemically identical to the fructose in fruit and high-fructose corn syrup. Bulk fructose powder is typically 99%+ pure crystalline fructose, dissolves cleanly in cold water, and tastes about 1.7× sweeter than table sugar (sucrose).
In a sports-drink context, fructose has one specific job: it uses the GLUT5 transporter, which is independent of the SGLT1 pathway that glucose-yielding carbs (dextrose, maltodextrin, sucrose's glucose half) saturate at ~60 g/hr. Pairing fructose with a glucose source lets you stack absorption from two parallel pathways and push total carb intake to 90 g/hr or more.
How does it work in a sports drink?
Free fructose is absorbed via GLUT5 in the small intestine, then converted to glucose in the liver before reaching working muscles. That hepatic step makes fructose marginally slower to oxidize than glucose — but it doesn't compete with glucose at the gut, which is the bottleneck during exercise.
Trying to fuel with fructose alone is a bad idea. GLUT5 saturates at roughly 30–45 g/hr of fructose, and excess fructose in the gut draws water in (osmotically active) and causes bloating, cramping, and — at higher doses — diarrhea.
How do I use it at home?
Pair with maltodextrin at a ~0.8:1 ratio (i.e., 0.8 g fructose per 1 g maltodextrin) for the 1:0.8 glucose-to-fructose ratio that O'Brien & Rowlands identified as practically optimal at high carb intakes.
For 80 g/hr of total carbs at 1:0.8: roughly 44 g maltodextrin + 36 g fructose. For 60 g/hr: roughly 33 g maltodextrin + 27 g fructose.
At lower total carb intakes (<60 g/hr), the ratio matters less and plain sucrose (a natural 1:1 glucose-fructose disaccharide) is a perfectly fine, even cheaper, substitute.
Dose & usage at a glance
- GLUT5 absorption ceiling
- ≈30–45 g/hr
- Per-hour intake at 1:0.8 ratio (60 g/hr)
- ≈27 g fructose
- Per-hour intake at 1:0.8 ratio (90 g/hr)
- ≈40 g fructose
- Sweetness vs sucrose
- ≈1.7×
Where to buy it in bulk
We primarily recommend Nutricost-brand products (made in GMP-compliant, FDA-registered facilities, third-party tested), with NOW Foods or BulkSupplements as fallbacks for ingredients Nutricost doesn't stock. The list below shows every channel that carries the product — Nutricost direct, iHerb, and Amazon — sorted by unit price. Pack sizes vary across retailers, so the lowest $/g usually means the largest pack — pick whichever store and size fits your usage. Links are affiliate — the site earns a small commission at no extra cost to you. For ingredients none of the three brands carries (HBCD, table salt, sucrose) we describe the typical specialty- or grocery-store option and skip the affiliate link.
Disclosure: As an Amazon Associate I earn from qualifying purchases.
DIY teardowns that use fructose
- DIY Maurten 320: the same 1:0.8 formula for a fraction of the price
- DIY SiS Beta Fuel: the most copyable branded fuel on the shelf
- DIY Precision PF 30: replace the fuel, not the sweat test
- DIY Neversecond C30: the research-forward gel without the $3.50 price tag
4 teardowns— all walk through how fructosefits into the specific commercial product's formulation.