Supplements: What They Can and Cannot Do, and What to Take

By: Alexander Leritz, sports nutritionist and registered dietitian in Toronto, reviewed by the JM Nutrition Team of dietitians and nutritionists

Do supplements actually work? Which supplements work and which do not work? Which supplements should I take?

These are just some of the common questions asked of our sports dietitians and other nutritional practitioners.

To do the subject justice, some background information is necessary.

Supplements: Background Information

Powders, Pills, and Empty Promises

In 2024, the dietary supplement market in Canada brought in nearly $19 billion USD, with analysts expecting it to be over $39 billion USD by 2034 (1). This is despite the alarming lack of evidence from the scientific community that many of these supplements are effective.

A huge meta-analysis in the 2024 JAMA reanalyzed data from almost 400,000 healthy people. The result was unambiguous. Daily multivitamins had no significant effect on the incidence of cancer, cardiovascular disease, or death (2).

The narrative that surrounds performance-enhancing supplements is much the same. Supplement companies often aggressively target and market supplements to athletes and fitness enthusiasts.

While they can be tempting, the claims made about fat burners, muscle builders, and testosterone boosters often lack solid scientific evidence. Some supplement products lack testing, while others show effects so small that they don’t matter in practice (3).

Most rely on persuasive marketing, not proven benefit.

Consistent effort achieves better results than anything else. Studies show that regular exercise, proper nutrition, sleep, and recovery improve health, performance, and long-term outcomes (4, 5).

A handful of supplements out there may be of some use, but even the top ones do their best work when they are alongside good nutrition and exercise.

The Foundation is the Fix

Lasting long-term change doesn’t start with supplements. It starts with the fundamentals.

Regular exercise, wholesome, nutritious diet, adequate sleep, and being able to stick to a routine are the tried and true methods to improve your health and performance.

While this may not be flashy, the effectiveness is well-supported by research.

1. Eat Like It Matters, Because It Does

Your diet affects your bodily and mental health. As such, it can influence how well you perform and recover. The food that you eat provides so much more than just calories. It also delivers a range of nutrients that your body need.

Muscles require protein to rebuild and repair. Fruits and vegetables are full of essential vitamins, minerals, and antioxidants. Healthy fats in the diet are important for hormone balance, brain health, and nutrient absorption.

For example, the benefits of bananas are more than just a quick energy boost. They also offer potassium and fibre to support hydration and to assist digestion and muscle function.

Salmon is a good source of high-quality protein, omega-3 fatty acids, and vitamin D, which may aid recovery and reduce inflammation.

The benefits of whole foods include nutrient synergy. Vitamin C, for instance, helps your body absorb iron better. Consuming dietary fats improves the absorption of vitamins A, D, E, and K. The synergistic effects of whole foods make them more beneficial than individual nutrients.

That’s something supplements can’t replace. Real food powers real results.

2. Motion with Intention Makes Momentum

Exercise improves both your physical and mental well-being.

Regular movement, whether lifting, running, swimming, cycling, walking, or taking part in any other form of exertive activity, improves cardiovascular fitness, muscular strength, and endurance.

Being active also supports some of the most essential functions of brain health. It sharpens focus and silences mental chatter. It amplifies the boost of a healthy mood when you’re already feeling happy (6).

You don’t need everything to be perfect. What matters is that you move consistently and purposefully. Small efforts, done regularly, drive change.

Training with intention means progressing gradually. It’s about paying attention to your body’s needs and maintaining a routine. When you do that, your body adapts. It becomes stronger, faster, and more efficient.

3. Growth Happens in the Quiet

Exercise creates the stimulus for growth. But real progress occurs during recovery. The body undergoes major rebuilding during rest, especially during sleep. The body repairs muscle tissue, replenishes energy stores, and the brain solidifies new information (7, 8).

Lack of sleep leads to poor performance, slower reflexes, difficulty concentrating, extended recovery periods, and a heightened risk of injury.

Adults generally require seven to nine hours of sleep nightly. Getting enough rest means setting a consistent bedtime, limiting screens before bed, and creating a sleep-friendly environment.

Recovery involves more than just sleep. It also requires hydration, good nutrition, rest days, and light exercise to boost circulation. These practices reduce fatigue and support long-term training adaptations.

Neglecting recovery will limit your progress, no matter how well you train or eat.

4. (Effort + Consistency) × Time = Progress

Lasting results depend on what you do consistently.

Your effort makes a difference. But effort without consistency fades quickly. Even consistent effort takes time to produce visible results.

You don’t have to be perfect. You just have to keep showing up. A single missed session won’t hurt your progress, but missing sessions regularly will.

Those who succeed aren’t always the most motivated. Those who persevere even when they lack motivation are often the ones who succeed. They’ve built systems and routines that carry them forward.

Progress often feels slow. Some days, it may feel invisible, but over time it becomes undeniable.

There is no shortcut. The equation stays the same.

(Effort + Consistency) × Time = Progress

That’s how change happens.

Supplements, as the Name Suggests, Supplement an Established Nutrition and Exercise Regimen

Supplements are often the first thing people buy when they want to improve their fitness or health. A quick fix, a small shortcut, something that feels like a smart start.

But that’s not their purpose.

Supplements support your efforts, not lead them. Without consistent training, solid nutrition, and enough rest, most supplements will not do much. Supplements cannot replace the basics.

When Supplements Can Help

Some supplements are useful, especially when they can fill a clear gap.

1. Protein Powders

Protein powders may help you meet your daily protein goals, especially when your schedule is busy and cooking is impractical, your appetite is low, or your training demands a higher intake of protein to support growth and recovery.

Although ideal, preparing full meals isn’t always realistic, especially when traveling or during busy workdays. In these cases, a high-quality protein powder may offer a quick, convenient way to support muscle repair and help achieve protein intake goals.

It is not a replacement for balanced meals. However, it can serve as a useful tool when consistency is difficult to achieve through food alone.

2. Creatine

Scientists have studied creatine for decades across a variety of populations, from recreational lifters to elite-level athletes.

Its primary role is to support the production of adenosine triphosphate (ATP), which is the energy currency used in short bursts of high-intensity activity9. It supports strength, power, and improves performance in resistance training, sprinting, and explosive movements (9).

At recommended doses, creatine has a proven safety record. It is a cost-effective, easy-to-dose sports supplement that is beneficial for both beginners and elite-level athletes.

While it is not essential, it is one of the few science-backed supplements that consistently delivers measurable performance benefits when used alongside structured training.

3. Fish Oil

Fish oil, rich in anti-inflammatory Omega-3 fatty acids, may help decrease inflammation. These fatty acids play a key role in regulating the inflammatory response by reducing chemicals that can cause swelling, stiffness, and soreness and can have benefits for recovery, joint pain relief, and for promoting heart health (11).

Individuals consuming small amounts of fatty fish such as salmon, mackerel, and sardines might require Omega-3 fatty acid supplementation. Therefore, fish oil supplements can be helpful, especially with limited food sources.

4. Vitamin D

Vitamin D plays many crucial roles in the body, including bone health, immune function, and muscular performance (12). Inadequate vitamin D is associated with a number of health problems, including fatigue, bone weakness, impaired recovery, and increased susceptibility to illness (12).

Deficiency is common, especially in individuals living in the northern areas where winters are harsher and last longer, with limited sunlight.

In fact, according to the Canadian Health Measures Survey (CHMS), which collected blood samples from 10,761 people from January 2016 to December 2019, 32% of Canadians showed suboptimal vitamin D levels necessary for bone health (13).

Even when following a healthy diet, it is difficult to get enough vitamin D from food alone. Fatty fish, egg yolks, and fortified dairy products contain small amounts, but often not enough to meet daily needs.

In these cases, the supplement is solving a specific problem. It is not a shortcut. It is support.

What Most Supplement Products Cannot Do

Many other supplement products do not live up to the claims on the label.

Fat burners usually rely on stimulants. They may temporarily curb appetite or provide a boost of energy for a few hours, but they do not burn a substantial amount of fat as a stand-alone product.

Testosterone boosters often rely on herbs that lack sound scientific evidence. And, pre-workout supplements may make you feel more alert and energized temporarily, but they will not make up for poor sleep or weak training habits.

Sometimes, ingredients do in fact show promise in prior research. However, final products often contain small doses or untested combinations as proprietary blends. The label might look convincing, but the science often just does not hold up.

Why Supplements Come Second, Not First

It is easy to focus on supplements when starting out. They seem helpful. They are simple and make big claims, and may feel like a step in the right direction. But on their own, supplements do not promote progress.

Many individuals will start buying supplements before they have built their solid foundation and habits. One might skip meals or workouts and hope that a shake or pill might make up for it.

But this approach rarely works. They cannot fix poor sleep or make up for missed exercise. They can support good habits, but they cannot take their place.

Genuine progress comes from structure. Show up, eat well, and recover properly. If those things are not happening yet, no supplement will change that.

Supplements Are Not Always Harmless

People often believe that supplements are safe and well-regulated. Unfortunately, this is not always the case.

Taking too much of certain vitamins, like vitamin A or iron, can cause harm. Some supplements may not mix well with medications. Others can raise your blood pressure or affect your heart. Poor regulation of some supplements may also mean that they may contain unlisted ingredients.

For athletes, that is a serious risk. Contaminated supplements have led to failed drug tests, even when athletes thought they were following the rules.

For the public, the bigger issue is usually financial. Many spend hundreds of dollars each year on supplements that do not help. One might better spend that money on high-quality food, coaching, or recovery tools.

How to Decide What Supplements are Worth Taking

Before you add anything new to your routine, stop and ask:

What problem am I trying to solve?
Can I address it through food, training, or rest?
Is there solid evidence that this works?
Have I built a consistent routine already?

If you are unsure about your answers, it might not be the best time to add something new.

First, concentrate on developing a consistent routine. If the supplement still seems helpful later on, consider whether it may be beneficial to incorporate it into your routine.

In addition, if you choose a product, make sure it is tested. Third-party certifications like NSF or Informed Sport help protect against contamination and false claims.

Final Thoughts on Supplements: Focus on What Moves The Needle

Supplements can be helpful in the right situations. They can help to fill small gaps in your diet or add structure when life gets busy. They can have value.

But too often, people treat them as the centrepieces of their routine. Companies frequently market them as the key to success. This is where expectations can go off course and problems can arise.

What consistently drives results is both simple and challenging. Showing up when it’s not convenient, preparing food when takeout feels easier, going to bed on time, training with purpose, recovering with intention. These are the habits that create progress.

They are not exciting. They do not come in flashy packaging. But they work. And if you stick with them, they lead to lasting results.

Introduce supplements only after establishing firm fundamentals. Inconsistent training, unbalanced meals, or neglected sleep will prevent any supplement from creating meaningful change. Effort must come first.

Context is also key. A supplement that works well for one person may offer no benefit to another. What matters is identifying the need, reviewing the evidence, and deciding based on your goals, not on marketing claims.

This requires honesty and discipline. It requires stepping back and asking whether a product solves a problem or simply masks a lack of structure.

Most of all, remember this: supplements should never replace the work. They should follow it.

Your results will come from what you repeat. From the meals you prepare, the training sessions you complete, the nights you sleep well, to the recovery you take seriously.

These are the details that matter. These are the habits that move the needle.

Conclusion

We hope that the information provided in this post shed some light on what supplements can do and what they cannot do. As always, if you require personalized support pertaining to supplementation or related concerns, please get in touch with us.

References

Expert Market Research. Canada dietary supplements market size, share, trends, growth 2024–2032. Expert Market Research. https://www.expertmarketresearch.com/reports/canada-dietary-supplements-market
Zhang Y, Manson JE, Sesso HD. Effect of multivitamin use on cancer and cardiovascular disease in adults: a systematic review and meta-analysis. JAMA Netw Open. 2024; 7(1):e2254309. doi:10.1001/jamanetworkopen.2022.54309
Lun V, Erdman KA, Reimer RA, Fung TS, Reimer ML. Dietary supplementation practices in Canadian high-performance athletes. Br J Sports Med. 2018;52(7):439–440. doi:10.1136/bjsports-2016-097270
Cunha LA, Costa JA, Marques EA, et al. The impact of sleep interventions on athletic performance: a systematic review. Sports Med Open. 2023; 9:58. doi:10.1186/s40798-023-00599-z
Puga TB, Mazumder RM, Ruan T, Scigliano N, Thiel GE, Treffer K. Sleep, nutrition, hydration and rest: the equal importance of external factors outside of training and practice for sports injury prevention. Sci J Sport Perform. 2023;2(4):428–438. doi:10.55860/LZNO4932
Public Health Agency of Canada. Physical activity and your health. Canada.ca. Updated January 13, 2023. https://www.canada.ca/en/public-health/services/being-active/physical-activity-your-health.html
Kaur H, Saper CB. Physiology, Sleep Mechanism. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2024.
Van Cauter E, Spiegel K. Sleep and the regulation of hormonal and metabolic processes. Sleep Med Clin. 2007;2(2):201–215. doi:10.1016/j.jsmc.2007.04.002
Wax B, Kerksick CM, Jagim AR, Mayo JJ, Lyons BC, Kreider RB. Creatine for Exercise and Sports Performance, with Recovery Considerations for Healthy Populations. Nutrients. 2021; 13(6):1915. https://doi.org/10.3390/nu13061915
Mayo Clinic Staff. Creatine. Mayo Clinic. Updated June 9, 2023.
Simopoulos AP. Omega-3 fatty acids in inflammation and autoimmune diseases. J Am Coll Nutr. 2002;21(6):495-505. doi:10.1080/07315724.2002.10719248
National Institutes of Health, Office of Dietary Supplements. Vitamin D—Health Professional Fact Sheet. NIH ODS. Updated March 24, 2022.
Statistics Canada. Shedding light on Canada’s vitamin D levels as we approach the shortest day of the year. StatCan. Published December 20, 2021.

About Authors

Alexander Leritz is a registered dietitian and sports nutritionist who works a wide range of athletes providing nutritional support for strength training, various team, individual and youth sports, endurance athletes and more.

JM Nutrition is a nutritional counselling service by nutritionists and dietitians across Canada, servicing every province and territory.

Primary offices: JM Nutrition Toronto, JM Nutrition Ottawa, JM Nutrition Halifax, JM Nutrition Vancouver

Our nutrition blog has been named one of the Top 100 Nutrition Blogs, Websites and Newsletters to Follow in 2021-2025 and one of the Top Canadian Nutrition Blogs by Feedspot. So don’t miss out and subscribe below to both the newsletter that includes latest blog posts.