Sport carbohydrate (glucose + fructose)
Carbohydrate taken during long exercise is the one sport product with a real, well-tested effect on performance. Ordinary food works as well; the products buy exact grams, convenience and batch testing for banned substances.
At a glance
| Our verdict | For events over 2 to 2.5 hours: the one sport product with a real performance effect. With our game-day guide. |
| Best use | Endurance events over 2 to 2.5 hours |
| How sure the evidence is | High against water; Moderate for the glucose-plus-fructose blend |
| Cost a month | About $80 to $100 for 4 long sessions; the food equivalent about $3 to $5 |
Written for adults in Canada. It explains the evidence; it is not advice for you personally. Last reviewed 20 October 2026.
Supplement Check
Is it right for you?
How much carbohydrate you need depends on your sport, how long you go and your gut. Diabetes medicines, fructose intolerance and drug testing all change the plan, and your check covers each one. Our Supplement Check looks at:
- Hereditary fructose intolerance: never a fructose-containing product
- Type 1 diabetes, any insulin, or gliclazide, glyburide or glimepiride
- A past eating disorder, or 2 or more on the eating-disorder screen (SCOFF)
- Pregnancy
- Stimulant medicine or a heart-rhythm problem
- Every medicine you take
Coming soon. The Supplement Check and the Online Health Assessment open once our safety testing is complete.
$59 when it opens, paid once. Adults 18 and over, anywhere in Canada. While the service is new, Dr. French reads every report himself, and your report arrives within 3 working days. More about the Supplement Check
What it is
Carbohydrate in a drink, gel or chew, taken during exercise. Single-sugar products use glucose, dextrose or maltodextrin (short chains of glucose). “Dual-source” products add fructose, at about 2 parts glucose to 1 part fructose, or 1 to 0.8 for the highest intakes. Many also contain sodium (100 to 500 mg) and some contain caffeine.
These are foods in Canada, not natural health products, so they have no NPN. Health Canada classed sports electrolyte drinks and powders as foods in April 2026; [1] gels and chews are ordinarily sold as foods too. So our quality rule for this group is batch testing for banned substances (Informed Sport, where every batch is tested before release, [2] or NSF Certified for Sport), for every buyer. Products that met this rule when we checked on 20 Oct 2026 include Precision Fuel PF 30 Gel (30 g, 2:1, on the Informed Sport register) [3] and, for events over 2.5 hours, Science in Sport Beta Fuel or Maurten Drink Mix 320 (both certified by Informed Sport).
How it acts
Carbohydrate during exercise keeps blood sugar up, keeps the muscles burning carbohydrate, and spares the liver's glycogen stores late in the event. [4] Glucose crosses the gut wall on one carrier, which is full at about 60 g an hour; fructose uses a different carrier, so the blend lets about 90 g an hour through and lets the body burn up to 1.75 g a minute, against about 1 g a minute with glucose alone. [5]
In events under about an hour, the effect is in the brain: carbohydrate receptors in the mouth switch on reward and movement areas, which is why rinsing the mouth works even without swallowing. [6, 7]
What it is used for, and what the evidence says
Used for fuel during exercise over about 75 minutes, for a top-up in the last hour before the start, and to refill glycogen when the next session is within 8 hours.
| Use | What the trials found | How sure we are |
|---|---|---|
| Carbohydrate against water, exercise over about an hour | In 61 performance studies (679 people), 82% showed a clear benefit, and the benefit grows with the length of exercise. [6] The joint sports nutrition position stand (including Dietitians of Canada) advises 30 to 60 g an hour for 1 to 2.5 hours and up to 90 g an hour beyond 2.5 hours. [8] The trials were small, but the direction was the same in almost all of them. | High |
| Glucose plus fructose against a single sugar, 2.5 to 3 hours | 14 trials: at the same calories, the blend raised average power by 1 to 9% (the range ran from 0 to 19%), and by 4 to 9% at the highest intakes. [9] Mostly men, mostly cycling. | Moderate |
| 120 g an hour against 90 g an hour | In trained cyclists, 120 g an hour raised the carbohydrate burned (1.51 against 1.29 g a minute) but did not spare more glycogen. [10] In 8 elite marathon runners it lowered the oxygen cost of running, but nausea, fullness and cramps were worst at 120 g. [11] A drink, gel or chew made no difference. [12] A 2026 expert review says the ceiling “could” rise to 120 g for trained athletes. [4] No trial yet shows faster times at 120 than at 90 g an hour. | Low |
| Team sport (60 to 120 minutes, stop-start) | The position stand advises 30 to 60 g an hour. [8] Team sport trials are fewer and mixed, and they were left out of the main review. [6] | Low to Moderate |
| Food against sport products | 15 small studies: no difference in performance between food and sport products, with slightly more gut symptoms from food, mainly in events over 2 hours. [13] | Low |
| Training the gut | Two weeks of practising race feeding (90 g an hour) cut gut symptoms by about 60% and improved a 1-hour running test by 5.2% against a 2.1% fall on placebo (25 people). [14] A second trial found the same, [15] and a review found gut discomfort fell 47% after 2-week carbohydrate programmes. [16] | Low to Moderate |
| Mouth rinse (swish and spit) | In cycling time trials, a small rise in average power (a standardised difference of 0.25, which is small); time to finish did not change. [17] After a meal the effect was smaller still (0.18). [18] | Moderate fasted; low fed |
| Gel-forming “hydrogel” drinks | Across 7 trials, no better than the same carbohydrate without the gel; [19] one small trial found a 2.1% faster 5-km run. [20] A certified hydrogel brand works as an ordinary carbohydrate product; the gel is not the reason. | Moderate (no advantage) |
How sure we are: High means further research is very unlikely to change the answer; Moderate, it might; Low, it may well change; Very low, we are very unsure. These follow the GRADE method that guideline panels use.
Benefits
- Less fade late in events of over about 2 hours: typically a few percent, more the longer the event. [6] Trials differ too much to quote one number.
- Glucose plus fructose over a single sugar at high intakes: 1 to 9% more average power. [9]
- Gut training: about 60% fewer gut symptoms in 2 weeks. [14]
- In the heat the benefit is less certain: 5 of 9 trials were positive. [21]
Risks and side effects
- Gut symptoms (nausea, bloating, cramps, diarrhoea) rise with the rate of intake and with a personal history of gut trouble; serious symptoms in about 31% of Ironman athletes in one survey. [22]
- Too much fructose gives diarrhoea in people who absorb fructose poorly; they use a glucose-only product, up to 60 g an hour.
- Teeth: frequent gels and acidic drinks wear enamel and cause decay.
- Blood sugar swings in diabetes treated with insulin if the insulin is not adjusted.
- Caffeinated versions: palpitations, poor sleep, gut upset.
- Drinking too much in long events can drop the sodium in the blood to a dangerous level (confusion, vomiting, seizures). Drink to thirst. [23, 24]
- Banned substances in uncertified products. This is rare for plain carbohydrate, but 14.8% of 634 non-hormonal supplements contained undeclared steroids, [25] and 38% of 66 high-risk sport supplements contained undeclared doping substances. [26]
- Not a reason for refined carbohydrate on rest days.
Interactions with medicines
Sugars do not change how the liver clears medicines: no enzyme induction or inhibition. The interactions are with blood sugar, and with caffeine in caffeinated versions.
| Medicine | What can happen | What to do |
|---|---|---|
| Insulin; gliclazide, glyburide, glimepiride | Carbohydrate during exercise changes blood-sugar control | No sport product from the check; a doctor-set fuelling plan |
| GLP-1 medicines (semaglutide, tirzepatide) | Slower stomach emptying, so gels may sit badly (practical experience, not trials) | Practise in training; smaller, more frequent feeds |
| Metformin, SGLT2 inhibitors | No interaction specific to carbohydrate | None |
| Stimulants (methylphenidate, amphetamines), theophylline, some antidepressants | Caffeinated versions add to heart rate and blood pressure | Caffeine-free versions only |
Who should not take it
- Hereditary fructose intolerance: never a fructose-containing product.
- Type 1 diabetes, any insulin, or gliclazide, glyburide or glimepiride: a doctor sets the fuelling plan first.
- A past eating disorder, or 2 or more on the eating-disorder screen (SCOFF): the whole report stops.
- Pregnancy: carbohydrate itself is not a concern; caffeine-free versions if caffeine would go over 200 mg a day.
- Stimulant medicine or a heart-rhythm problem: caffeine-free versions only.
- Heart failure or kidney disease: the sodium in the product counts.
- Drug-tested athletes. We ask by example, because few people know the term: a national or provincial team, carded athlete or Canada Games; university or college sport (U SPORTS, the CCAA, NCAA); junior hockey (QMJHL, OHL, WHL); a professional or minor-professional league (AHL, ECHL and others); or anyone told they can be tested. “Not sure” counts as yes. Then only a product on the NSF Certified for Sport or Informed Sport register, batch-tested, and the report goes to Dr. French before release.
- Under 18: outside the Supplement Check (the service is for adults).
Dose and timing
- Dr. French's game-day timing: last real meal 3 to 4 hours before, built on starch with a little lean protein (about 1 to 2 g of carbohydrate per kg), finished by 3 hours before. No fat from 3 hours before any hard effort. Carbohydrate only from 3 hours to 1 hour out (white toast with jam, a banana, a plain bagel). Simple sugar only in the last hour (20 to 30 g: one gel or 500 mL of sports drink).
- Honest note on the fat rule: it is a gut-comfort rule. A high-fat meal before exercise has not been shown to harm performance, [27, 28] but a gut that is still digesting fat is a common cause of trouble.
- During: under 45 minutes, none needed (water to thirst); 45 to 75 minutes, small amounts or a mouth rinse (25 mL, swish 5 to 10 seconds, spit, every 10 to 15 minutes); 1 to 2.5 hours, 30 to 60 g an hour (a single sugar is enough); over 2.5 hours, 60 to 90 g an hour of a 2:1 glucose-plus-fructose product. [8]
- Up to 120 g an hour (1:0.8 blend) only for trained athletes in events over 3 hours, after 2 weeks of gut training. [10, 4]
- Split into doses every 15 to 20 minutes. Take a gel with about 150 to 250 mL of water unless it is made to be taken without; drinks of 4 to 8% carbohydrate. Drink, gel or chew: the form does not change absorption. [12]
- Practise in training first. Never try anything new on game day.
- After: if you go again within 8 hours, about 70 g of carbohydrate an hour for the first 4 hours plus 20 to 40 g of protein; otherwise, normal meals.
- Store at room temperature; keep out of hot cars (gels separate); use by the best-before date.
- How to tell it is working: less late fade and better finishing pace or power across 2 or 3 matched sessions; a gut score (0 to 10) that falls over 2 weeks of practice. A gut score of 4 or more, vomiting or diarrhoea: slow the rate, switch to a single sugar under 60 g an hour, and talk to us.
What we know about Canadians
About 27% of Canadians aged 15 and over played a sport regularly in 2016, and 14% of those competed. [29] In 2024–25 the Canadian Centre for Ethics in Sport (now Sport Integrity Canada) ran 3,423 tests under the Canadian Anti-Doping Program; university sport was the most tested (524 tests). Fourteen rule violations were listed, mostly anabolic agents, SARMs and stimulants, and one for pseudoephedrine. [30] Any of these can turn up in a contaminated sport product, which is why tested athletes use only batch-tested products.
Most at risk of a positive test from a product: university and national-team athletes, powerlifters and weightlifters, and anyone buying untested pre-workout, “recovery” or muscle products.
How sure are we: high. Official counts: Statistics Canada General Social Survey 2016 and the anti-doping program's 2024–25 statistics. There is no Canadian data on how much carbohydrate athletes take.
An honest comparison: fuel during long exercise
There is no medicine for this outcome. The standard approach is food-based fuelling to the sports nutrition position stand. Cost a month is for 4 long sessions of 2 hours at 60 g an hour (480 g).
| Option | Effect | How sure we are | Cost a month (CAD) |
|---|---|---|---|
| Batch-certified gels and drink mixes (glucose plus fructose over 2.5 hours) | The same carbohydrate effect as food, in exact grams; 1 to 9% more power than a single sugar at high intakes [9] | Moderate to High | About $80 to $100 |
| Hydrogel premium over a standard certified 2:1 product | No added effect [19] | Moderate | About 30 to 50% more |
| Ordinary food and sugar drinks (banana, jelly sweets, sugar plus salt plus water; table sugar is half glucose, half fructose) | Same performance as sport products; slightly more gut symptoms over 2 hours [13] | Low | About $3 to $5 |
| Gut training (practise race feeding for 2 weeks) | Gut symptoms about 60% fewer; performance 4 to 5% better [14] | Low to Moderate | Free |
| Mouth rinse, events under about an hour | Small rise in average power, mainly when fasted [17] | Moderate fasted | Free |
| None | There is no medicine for this outcome | — | — |
Read honestly: food works as well as the products. What you pay for is convenience, exact grams and, for drug-tested athletes, batch certification. Training your gut is free and makes either work better.
Our verdict
For adults in continuous exercise of over about 75 minutes (running, cycling, triathlon, skiing, hockey tournaments, long team-sport days): carbohydrate during exercise, at the rate the plan sets for the length of the event. For events over 2 to 2.5 hours, a batch-certified glucose-plus-fructose drink or gel. Food does the same job if you prefer it; practise either in training first.
Not for anyone with hereditary fructose intolerance (fructose products), and not without a doctor's plan in diabetes treated with insulin or a sulfonylurea. Drug-tested athletes use only Informed Sport or NSF Certified for Sport products.
This is the one sport product with a real, well-tested effect: high certainty against water, and moderate certainty that the glucose-plus-fructose blend does better than a single sugar at high intakes. There is no medicine for the job, and ordinary food works as well, so we say so. The premium technologies (hydrogel, cluster dextrin, isomaltulose) add cost, not performance. Dr. French's game-day timing (no fat from 3 hours out, carbohydrate only from 3 hours, simple sugar only in the last hour) is stricter on fat than the evidence requires; it is a gut-comfort rule, and we say that too. Because these products are foods with no NPN, batch testing for banned substances is our quality gate for every buyer.
Supplement Check
Before you buy it, get it checked
How much carbohydrate you need depends on your sport, how long you go and your gut. Diabetes medicines, fructose intolerance and drug testing all change the plan, and your check covers each one. Our Supplement Check looks at:
- Hereditary fructose intolerance: never a fructose-containing product
- Type 1 diabetes, any insulin, or gliclazide, glyburide or glimepiride
- A past eating disorder, or 2 or more on the eating-disorder screen (SCOFF)
- Pregnancy
- Stimulant medicine or a heart-rhythm problem
- Every medicine you take
Coming soon. The Supplement Check and the Online Health Assessment open once our safety testing is complete.
$59 when it opens, paid once. Adults 18 and over, anywhere in Canada. While the service is new, Dr. French reads every report himself, and your report arrives within 3 working days. More about the Supplement Check
Disclosure of financial interest
White Pine Medical earns money from products bought through our Fullscript dispensary. Dr. French's Code of Ethics requires him to tell you this. You do not have to buy anything from us: every product is named by its ingredient and dose so you can buy it at any pharmacy, and the advice is the same wherever you buy it, or if you buy nothing.
References
- Health Canada. Public notice: classification of sports electrolyte products as foods. 23 Apr 2026. https://www.canada.ca/en/health-canada/services/food-nutrition/supplemented-foods/public-notice-classification-sports-electrolyte-products-foods.html
- Informed Sport. The benefits (every batch tested before release). https://sport.wetestyoutrust.com/about/the-benefits (read 20 Oct 2026).
- Informed Sport register: Precision Fuel & Hydration PF 30 Energy Gel. https://sport.wetestyoutrust.com/supplement-search/precision-fuel-hydration/pf-30-energy-gel (read 20 Oct 2026).
- Morton JP, Fell JM, Gonzalez JT, Hearris MA, Podlogar T, Pugh JN, et al. From metabolism to medals: contemporary perspectives and revisiting carbohydrate guidelines for fueling endurance athletes during exercise. J Nutr. 2026;156(5):101442. PMID 41759826.
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- Thomas DT, Erdman KA, Burke LM. Position of the Academy of Nutrition and Dietetics, Dietitians of Canada, and the American College of Sports Medicine: nutrition and athletic performance. J Acad Nutr Diet. 2016;116(3):501-28. PMID 26920240.
- Rowlands DS, Houltham S, Musa-Veloso K, Brown F, Paulionis L, Bailey D. Fructose-glucose composite carbohydrates and endurance performance: critical review and future perspectives. Sports Med. 2015;45(11):1561-76. PMID 26373645.
- Podlogar T, Bokal Š, Cirnski S, Wallis GA. Increased exogenous but unaltered endogenous carbohydrate oxidation with combined fructose-maltodextrin ingested at 120 g h-1 versus 90 g h-1 at different ratios. Eur J Appl Physiol. 2022;122(11):2393-401. PMID 35951130.
- Ravikanti S, Silang KG, Martyn HJ, Johnson KO, Louis JB, Bampouras TM, et al. 13C-labelled glucose-fructose show greater exogenous and whole-body CHO oxidation and lower O2 cost of running at 120 versus 60 and 90 g·h-1 in elite male marathoners. J Appl Physiol (1985). 2025;139(6):1581-95. PMID 41191077.
- Hearris MA, Pugh JN, Langan-Evans C, Mann SJ, Burke L, Stellingwerff T, et al. 13C-glucose-fructose labeling reveals comparable exogenous CHO oxidation during exercise when consuming 120 g/h in fluid, gel, jelly chew, or coingestion. J Appl Physiol (1985). 2022;132(6):1394-406. PMID 35446596.
- Reynolds KM, Clifford T, Mears SA, James LJ. A food first approach to carbohydrate supplementation in endurance exercise: a systematic review. Int J Sport Nutr Exerc Metab. 2022;32(4):296-310. PMID 35231883.
- Costa RJS, Miall A, Khoo A, Rauch C, Snipe R, Camões-Costa V, et al. Gut-training: the impact of two weeks repetitive gut-challenge during exercise on gastrointestinal status, glucose availability, fuel kinetics, and running performance. Appl Physiol Nutr Metab. 2017;42(5):547-57. PMID 28177715.
- Miall A, Khoo A, Rauch C, Snipe RMJ, Camões-Costa VL, Gibson PR, et al. Two weeks of repetitive gut-challenge reduce exercise-associated gastrointestinal symptoms and malabsorption. Scand J Med Sci Sports. 2018;28(2):630-40. PMID 28508559.
- Martinez IG, Mika AS, Biesiekierski JR, Costa RJS. The effect of gut-training and feeding-challenge on markers of gastrointestinal status in response to endurance exercise: a systematic literature review. Sports Med. 2023;53(6):1175-200. PMID 37061651.
- Brietzke C, Franco-Alvarenga PE, Coelho-Júnior HJ, Silveira R, Asano RY, Pires FO. Effects of carbohydrate mouth rinse on cycling time trial performance: a systematic review and meta-analysis. Sports Med. 2019;49(1):57-66. PMID 30488186.
- Deng H, Fan X, Liu P, Song T, Ahmad Fuaad AA, Bin Mohd Nasiruddin NJ, et al. Fed, not fasted: is carbohydrate mouth rinsing still ergogenic? A three-level meta-analysis. J Int Soc Sports Nutr. 2025;22(1):2579027. PMID 41199504.
- Sutehall S, Muniz-Pardos B, Bosch A, Pitsiladis Y. The effect of sodium alginate and pectin added to a carbohydrate beverage on endurance performance, substrate oxidation and blood glucose concentration: a systematic review and meta-analysis. Sports Med Open. 2022;8(1):82. PMID 35727377.
- Rowe JT, King RFGJ, King AJ, Morrison DJ, Preston T, Wilson OJ, et al. Glucose and fructose hydrogel enhances running performance, exogenous carbohydrate oxidation, and gastrointestinal tolerance. Med Sci Sports Exerc. 2022;54(1):129-40. PMID 34334720.
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- Hew-Butler T, Rosner MH, Fowkes-Godek S, Dugas JP, Hoffman MD, Lewis DP, et al. Statement of the 3rd International Exercise-Associated Hyponatremia Consensus Development Conference, Carlsbad, California, 2015. Br J Sports Med. 2015;49(22):1432-46. PMID 26227507.
- Almond CS, Shin AY, Fortescue EB, Mannix RC, Wypij D, Binstadt BA, et al. Hyponatremia among runners in the Boston Marathon. N Engl J Med. 2005;352(15):1550-6. PMID 15829535.
- Geyer H, Parr MK, Mareck U, Reinhart U, Schrader Y, Schänzer W. Analysis of non-hormonal nutritional supplements for anabolic-androgenic steroids: results of an international study. Int J Sports Med. 2004;25(2):124-9. PMID 14986195.
- Duiven E, van Loon LJC, Spruijt L, Koert W, de Hon OM. Undeclared doping substances are highly prevalent in commercial sports nutrition supplements. J Sports Sci Med. 2021;20(2):328-38. PMID 34211326.
- Rowlands DS, Hopkins WG. Effect of high-fat, high-carbohydrate, and high-protein meals on metabolism and performance during endurance cycling. Int J Sport Nutr Exerc Metab. 2002;12(3):318-35. PMID 12432176.
- Murakami I, Sakuragi T, Uemura H, Menda H, Shindo M, Tanaka H. Significant effect of a pre-exercise high-fat meal after a 3-day high-carbohydrate diet on endurance performance. Nutrients. 2012;4(7):625-37. PMID 22852054.
- Statistics Canada. Sports for fun and fitness (General Social Survey 2016). 11-627-M2019039. https://www150.statcan.gc.ca/n1/pub/11-627-m/11-627-m2019039-eng.htm
- Canadian Centre for Ethics in Sport. CCES annual statistics, 1 Apr 2024 – 31 Mar 2025. https://sportintegrity.ca/sites/default/files/content/docs/2025-10/CCES-2024-25Stats-E.pdf
Costs marked as estimates are typical Canadian retail or pharmacy prices, before any drug plan. Certainty grades are ours unless the review gave its own.