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Scenario answer

Best fuel for a hot marathon with a sensitive stomach

Heat and a touchy gut pull in opposite directions: you need more sodium and more fluid, but every extra thing you swallow is a risk.

Carb target for this profile
≈ 55 g/hr
To hit ~55 g/hr carbs: about 1.8 C30 Fuel Drink Mix per hour (54 g/hr). Hot race: add an electrolyte drink at ~400–1000 mg/L sodium, for example Hydration Drink Tabs. Sodium's job is to keep you drinking (about 59% more fluid, Cosgrove 2013). It has no effect on cramping.

The three-product answer

#1 · 91% matchDrink Mixes · Drink

NEVERSECOND C30 Fuel Drink Mix

30 g carbs · 200 mg sodium · Science Score 100
  • Caffeine-free: good for the early miles, before you take caffeine.
  • 200 mg sodium: a good match for hot conditions.
  • High Science Score: a dual-source carb profile with little protein, the kind a sensitive gut handles best.
#2 · 91% matchDrink Mixes · Drink

Precision Fuel & Hydration Carb & Electrolyte Drink Mix (PF 30/60)

30 g carbs · 500 mg sodium · Science Score 100
  • Caffeine-free: good for the early miles, before you take caffeine.
  • 500 mg sodium: a good match for hot conditions.
  • High Science Score: a dual-source carb profile with little protein, the kind a sensitive gut handles best.
#3 · 91% matchDrink Mixes · Drink

Maurten Drink Mix 160

41 g carbs · 210 mg sodium · Science Score 100
  • Caffeine-free: good for the early miles, before you take caffeine.
  • 210 mg sodium: a good match for hot conditions.
  • High Science Score: a dual-source carb profile with little protein, the kind a sensitive gut handles best.

Electrolyte pairing for this profile: GU Energy Hydration Drink Tabs or Nuun Sport Tablets. Sodium's job is keeping you drinking, not preventing cramp.

Why

In the heat your blood is busy at the skin, not the gut, so absorption gets worse exactly when you need it most. A sensitive stomach starts the race with less headroom, so the target is capped around 55 g/hr rather than the 80–90 an iron gut can train up to.

What matters: dual-source (roughly 2:1 glucose:fructose) carbohydrate so two transport pathways share the load; sodium in the drink, at a concentration that keeps you drinking (400–1000 mg/L), because keeping fluid coming in is the real job of sodium in the heat; and a format you have practised, not the one that scored highest.

The trap is stacking a caffeinated gel on top of a hot, dehydrated gut. Keep caffeine modest and early, and rehearse the full plan on at least two long runs in similar heat before you trust it.

Also fits

NEVERSECOND C30 Energy Gel · 91% match · 30 g→NEVERSECOND C30+ Caffeine Energy Gel · 91% match · 30 g→Maurten Drink Mix 320 · 91% match · 80 g→Tailwind Nutrition High Carb Fuel · 91% match · 90 g→NEVERSECOND C90 High-Carb Drink Mix · 91% match · 90 g→

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