Few work. All carry some risk.
Supplements are marketed heavily to athletes, but only a handful have good evidence for improving performance, and only in specific situations. Others are useful only to correct a measured deficiency, such as iron or vitamin D. Most add cost without benefit.
There is also real risk. Supplements can be contaminated with substances that are banned in sport or harmful to health. Under anti-doping rules, athletes are responsible for anything found in their sample, whatever its source. In Canada, a Natural Product Number (NPN) means Health Canada has authorized a product for sale. It does not mean the product has been tested for prohibited substances.
Supplements with good evidence, and when they help
A short list, each useful only in certain sports and situations. Doses are typical research doses, not a prescription for you.
| Supplement | What it can do | Keep in mind |
|---|---|---|
| Caffeine | Endurance and high-intensity performance, alertness | About 3 mg per kg, 30 to 60 minutes before. More mostly adds jitters, stomach upset and poor sleep. |
| Creatine monohydrate | Repeated sprints, strength and power, muscle gain with training | About 3 to 5 g a day. May add 1 to 2 kg of water weight. One of the most studied supplements. |
| Beta-alanine | Hard efforts lasting about 1 to 4 minutes | Needs several weeks of daily use. A tingling skin feeling is common and harmless. |
| Sodium bicarbonate | Very hard efforts lasting about 1 to 7 minutes | Stomach upset is common. Test it in training, well before any competition. |
| Dietary nitrate (beetroot juice) | Endurance performance | Taken 2 to 3 hours before. The benefit is smaller in highly trained athletes. |
| Sports foods | Drinks, gels, bars and protein powder: convenient fuel and protein | Useful when food is impractical. They are foods, not performance boosters. |
Find your caffeine dose
Around 3 mg per kg of body weight, 30 to 60 minutes before exercise, is enough for most athletes. Coffee works as well as pills.
Health Canada: no more than 400 mg a day for adults, and 2.5 mg per kg a day for anyone under 18. Avoid caffeine late in the day, since sleep matters more. Not recommended as a performance aid for youth athletes.
A useful dose, about
210 mg
- Lower option (2 mg per kg)
- 140 mg
- In brewed coffee (about 135 mg per cup)
- 1.5 cups
Before you take anything: a three-step check
Essential if you are drug-tested in sport, and good practice for everyone.
- Step 1 · Check
Know what is in it
Read the full ingredient list, and check your medications too.
- Global DRO for medications
- Therapeutic use exemption, if needed
- Avoid proprietary blends
- Step 2 · Choose
Pick third-party tested products
Certification lowers the risk of contamination. It does not remove it.
- NSF Certified for Sport
- Informed Sport
- Batch-tested products
- Step 3 · Record
Keep a paper trail
If a test ever comes back positive, records help your case.
- Batch or lot number
- Receipt and photo of the label
- Keep a sealed sample
Ground rules
Food first
A well-planned diet covers most needs. A supplement should solve a specific problem that food cannot practically solve.
Test, do not guess
Iron (endurance athletes and people who menstruate), vitamin D (Canadian winters) and vitamin B12 (plant-based athletes) are the usual gaps. Supplement based on blood work or a clear dietary gap: too much iron can be harmful.
An NPN is not a doping test
In Canada, a Natural Product Number means Health Canada authorized the product for sale. It does not mean the product was tested for substances banned in sport.
Youth athletes
Performance supplements are generally not recommended for athletes under 18. The focus is on food, growth and skill.
WORKING WITH YOUR DIETITIAN
How we work on it together
Review what you take
Bring your supplements. We review each one’s purpose, dose and evidence, and possible interactions with your health and medications.
Decide what is worth it
For your sport and goals, we decide together what to keep, what to drop, and what food can do instead.
Plan safe use
If a supplement makes sense, we plan the dose and timing, test it in training, and check certification if anti-doping rules apply to you.
Common questions
Is creatine safe?
For healthy adults, creatine monohydrate at usual doses (about 3 to 5 g a day) has a strong safety record in research. It can add some water weight. Talk to your doctor first if you have kidney disease or take medications that affect the kidneys.
Do athletes need a multivitamin?
Usually not, if the diet is varied and covers energy needs. A multivitamin can make sense during restricted eating, travel or for specific gaps, but it does not fix low iron or vitamin D on its own.
Should I take vitamin D in winter?
In Canada, sun exposure is too low for much of the year to make enough vitamin D. Many athletes benefit from a supplement in winter; the right dose depends on your diet and, ideally, a blood test.
Does an NPN mean a supplement is free of banned substances?
No. A Natural Product Number means Health Canada authorized the product for sale. It is not a test for substances banned in sport. Look for NSF Certified for Sport or Informed Sport instead.
Do I need protein powder?
Not necessarily. It is a convenient food when meals are hard to fit in, not a requirement. Most athletes can meet their needs through food.
How do I know a supplement is safe for drug-tested sport?
No supplement is risk-free. Choose third-party certified products, check medications on Global DRO, and keep a record of what you take. Your sport’s anti-doping organization has the final word.
Are pre-workout products worth it?
Many contain high doses of caffeine plus ingredients with little evidence, sometimes in proprietary blends that hide the amounts. A measured dose of caffeine from coffee or a known product is often simpler and safer.
Based on current sports nutrition guidelines
- National Supplement Advisory Group (2023). Position statement on dietary supplementation in Canadian sport. Canadian Sport Institute.
- Maughan et al. (2018). IOC consensus statement: dietary supplements and the high-performance athlete.
- Guest et al. (2021). ISSN position stand: caffeine and exercise performance.
- Health Canada. Caffeine in foods: recommended maximum daily intakes.
- Australian Institute of Sport. Supplements framework and athlete resources.
- Global DRO. Check the anti-doping status of medications in Canada.
This page is general information, not individual advice. Your needs depend on your sport, health and goals.
Get a plan built for your sport.
Start with a free initial consultation, in person in Ottawa or Gatineau, or online anywhere in Ontario and Quebec.