Food

Take it or leave it: A science-backed glance at supplements

Practical tips on how to boost your health and support your fitness journey.

Emiliano Pena

29 Jul 2025 • 8 min read

From rainbow-coloured powders to glamorous gummies, supplements are everywhere. Promising better workouts, glowing skin or sharper focus, they fill our feeds and crowd our shelves. But are they worth your time (and money)?

Let's unpack the world of supplements, without the hype.

What are supplements?

Food supplements are concentrated sources of nutrients (such as vitamins and minerals) or non-nutrient compounds (like plant extracts, probiotics, or adaptogens) that aim to support health by complementing your diet.

You will find them in various forms, such as tablets, powders, capsules, or liquids, sold in pharmacies, fitness shops and online stores.

But just because they come in a sleek tub or a pastel bottle does not mean they work or that you need them.

Popular supplements you may know (and what science says so far)

Let's break them down by how they are marketed:

Physical performance

Creatine – One of the most researched supplements. Helps with short bursts of intense exercise and may speed up recovery. It is also being studied for its role in brain function.

Branched-chain amino acids (BCAAs) – May support muscle recovery. Still, if your overall protein intake is adequate, extra BCAAs likely offer little additional benefit.

L-carnitine – Promoted for fat burning and endurance, but results in human studies are mixed and often modest at best.

Mood and focus

Ashwagandha – An adaptogenic herb linked to reduced stress and anxiety. Some promising results, though quality and dosage vary widely between products. Adaptogens are not currently part of official UK dietary recommendations and should be approached with caution, especially if you take medications or have underlying conditions.

Lion's Mane – A mushroom with early evidence suggesting it may support memory, focus and mood. Sometimes described as an adaptogen, though it seems to work differently from herbs like Ashwagandha. Human studies are still limited, but they are growing.

Omega-3s – Important for brain and heart health. DHA, a type of omega-3 fat, is a key component of brain cell membranes. Low intake has been linked with mood disorders in some studies, although more research is needed.

Skin and joint health

Collagen peptides – Your body produces its own collagen when vitamin C intake is sufficient. When supplemented, collagen peptides may contribute to joint and skin health; however, further research on humans is needed to support this claim.

Plant-based extracts

Green tea extract – High in antioxidants, but in supplement form, it may cause liver toxicity at high doses. An alternative is to enjoy green tea as a beverage (either iced or hot, as you prefer).

Goji berry extract – Touted for its anti-ageing effects, but real-life benefits appear similar to those of eating a variety of fruits and vegetables.

Vitamins and minerals

Vitamin C – Supports immune health and collagen production, and it also improves iron absorption in the gut. Ever heard of scurvy, the sailor's disease caused by a lack of citrus on long sea voyages? That is what a vitamin C deficiency looks like.

Vitamin D – Essential for bone health, mood and immunity. In the UK, most people need a supplement from October to March. People with darker skin tones may require extra sun exposure year-round.

Vitamin B12 – Vital for nerve and red blood cell function. It is found mainly in animal products, so supplements are necessary for vegans unless fortified foods are regularly consumed.

Iron, calcium, magnesium, zinc – These minerals are needed for energy metabolism, muscle function, bone health and immunity. People who follow restrictive diets, do not eat a wide variety of whole foods, or train intensively, may be at higher risk of falling short. Testing before supplementing is recommended, as excessive intake can lead to imbalances or interfere with the absorption of other nutrients.

Gut health

Probiotics – Live bacteria that may help with gut health, especially after taking antibiotics or for conditions like irritable bowel syndrome. Benefits depend on the specific strains they contain and the dose.

Prebiotics – Types of fibre that nourish good gut bacteria. Found in foods like Jerusalem artichokes, garlic, onion and bananas. May support digestion and gut diversity. A gradual introduction is best to avoid bloating, unless you want to experience a gut symphony.

Fibre supplements – Psyllium husk and similar products can help with constipation or irregularity. Useful when diet falls short, but whole foods and adequate hydration are still the best options when possible.

Antioxidant support

Resveratrol – Found in red grapes and wine, with potential antioxidant and anti-inflammatory effects. It seems to be poorly absorbed, unless chemically modified (e.g., phosphorylated). Research in humans is ongoing, with modest benefits reported so far.

Coenzyme Q10 (CoQ10) – Seems to play a role in energy production and potentially heart health. It may benefit people taking statins, but routine use is not advised for everyone, as more research is needed.

Alpha-lipoic acid (ALA) – May support nerve health and blood sugar control, potentially in people with diabetes. Often marketed for its antioxidant properties, but the results are mixed.

Astaxanthin – A red pigment from algae and seafood, promoted for skin and eye health. Evidence in humans is limited and mostly preliminary.

Do you need supplements?

The short answer? Probably not. The longer answer? Sometimes, yes, in specific circumstances.

Ask yourself:

Are you vegan or mostly plant-based? You may need to top up your vitamin B12 intake with supplements or fortified foods.
Do you avoid oily fish? If so, consider an omega-3 supplement, such as algal oil for vegans.
Do you spend most of the day indoors or get little sunlight? A vitamin D supplement is recommended, especially in the autumn and winter months in the UK.
Do you train hard at the gym? Creatine could help with performance and recovery.
Do you feel constantly wired or burnt out? Some adaptogens (like Ashwagandha) might help, but they are not magical, and more research is needed.

If you are curious about a supplement, look for the science behind it, not just a shirtless guy selling you a dream.

Efficacy and bioavailability: Does your supplement actually work?

Not all supplements are created equal, and not all are absorbed and used equally by your body (bioavailability).

Some compounds must be present in a specific form to be effectively absorbed. Resveratrol, for example, is poorly absorbed by your gut unless it has been chemically modified (phosphorylated).

Do you get what you buy? Gummy supplements and powders may be tasty, but they may sometimes contain less of the active ingredient than claimed. A recent investigation showed that some creatine gummies, for instance, contained far less than the claimed dose.

Timing and pairing affect absorption. Fat-soluble vitamin supplements (A, D, E, K) should be taken with meals that contain fat. Plus, minerals like calcium and iron can compete with each other, so spacing them out is advised.

Look for quality-tested brands, and always double-check if the claim sounds too good to be true.

Potential downsides

Supplements may help support your health, but they are not without risks. Whether natural, synthetic, or somewhere in between, some may carry side effects or interact with medications. Some examples?

Green tea is generally considered safe as a beverage, although it may be risky when consumed in high-dose supplements.
Too much vitamin C intake may increase the risk of kidney stones.
Hypervitaminosis (too much of a vitamin) from over-supplementation is real and often goes unnoticed until symptoms appear.

Food first, back to the origins

Supplements should fill gaps in your diet, not replace food.

Here are some ways to naturally get the nutrients (and non-nutrients) they provide:

Creatine – In animal products such as meat and fish, vegans and vegetarians may benefit from a top-up.
Vitamin D – In oily fish (salmon, sardines, herring, mackerel, etc.), fortified foods and UV-exposed mushrooms. Your skin also makes it when exposed to sunlight, especially between March and October in the UK.
Magnesium and zinc – In nuts, seeds, legumes, tofu and whole grains.
Iron – In meat, lentils, tofu, beans and fortified cereals. Combine with vitamin C-rich foods to increase absorption.
Omega-3s – In oily fish, flaxseed, walnuts and chia seeds.
Adaptogens? Try getting a good night's sleep, going for a walk, or relaxing while sipping your herbal tea. No subscription needed.

Bottom line

Supplements can be beneficial when a deficiency is diagnosed or when lifestyle choices may limit the intake of specific nutrients. But they are not meant to be shortcuts. They will not replace your meals, your lifestyle, or your support network.

What can you do? Stay informed, think critically and if in doubt, speak with a healthcare professional, such as a registered dietitian. You deserve facts, not fads, and your health is worth that clarity.

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