“Let’s build a good diet first. Then supplement when necessary.”
— NourishMum
Some days, it feels as though looking after ourselves requires a small pharmacy in the kitchen.
Magnesium to help us sleep better.
Collagen for our skin and joints.
Omega-3 because we don’t eat enough fish.
Probiotics to look after our gut microbiome.
A multivitamin, just in case.
And then there’s vitamin D, vitamin C, zinc, electrolytes, adaptogens…
The list can get surprisingly long.
And almost without realising it, dietary supplements can start taking up more and more space in our kitchens.
And I understand the appeal. Taking a capsule is easy. It gives us the feeling that we’re doing something positive for our health and, in some circumstances, a supplement really can be useful.
But perhaps there’s a question we should ask ourselves before adding another bottle to the shelf: Do we actually need it?
Because supplementing a nutrient when we have a deficiency, increased nutritional needs or a specific health concern is very different from taking supplements indefinitely, just in case.
And perhaps, before asking ourselves which supplement we’re missing, we should start with something much more basic: What does our diet actually look like?
Supplements Should Complement Our Diet, Not Form Its Foundations
The word itself gives us a clue.
Supplement.
Something that adds to what is already there.
Not something we should build our entire diet around.
Food doesn’t simply provide isolated vitamins and minerals. It gives us protein, fats, carbohydrates, fibre and countless other compounds that interact with one another.
That’s why we can’t reduce a sardine to its omega-3, a handful of almonds to its magnesium or a pot of fermented yoghurt to a few particular bacteria.
A supplement can provide a specific substance.
Food provides a whole nutritional package.
That doesn’t mean supplements are unnecessary.
It means we should use them for what they are actually good at: filling a gap when there is a genuine reason to do so.
So, When Does Supplementation Make Sense?
There are situations in which taking supplements is entirely justified.
A confirmed deficiency.
A diet that excludes certain nutrients.
Problems with nutrient absorption.
A stage of life with particular nutritional needs.
A specific medical recommendation.
Or circumstances in which getting enough of a nutrient through food alone is difficult.
A classic example is folic acid around the time of conception and during early pregnancy. This isn’t about taking something just in case, but about a specific recommendation supported by scientific evidence.
The problem arises when we apply that same reasoning to everything: If a nutrient is important, taking more of it must be better.
And that simply isn’t always true.
Let’s look at some of the supplements we seem to encounter everywhere these days.
Magnesium: Does Everyone Need It?
Magnesium is probably one of the most talked-about supplements at the moment.
Sleep, stress, muscles, energy, cramps…
It seems to be recommended for everything.
And magnesium really is an essential mineral. It is involved in hundreds of reactions in the body, including those related to muscle and nerve function, protein synthesis and energy metabolism.
But there’s something we might not realise: a significant proportion of the population doesn’t get enough magnesium through their diet.
In Spain, the ANIBES study found that many people weren’t meeting recommended magnesium intakes. Other international studies have observed similar patterns.
Does that mean practically everyone is magnesium deficient?
Not exactly.
Consuming less magnesium than recommended isn’t the same as having a clinical deficiency. What’s more, assessing our magnesium status isn’t always straightforward, as most of the magnesium in our bodies is found in our bones and tissues rather than in our blood.
Magnesium is naturally present in foods such as leafy green vegetables, nuts, seeds, pulses and wholegrains.
However, including these foods in our diet doesn’t automatically guarantee that we’re meeting our needs.
The quantities we eat matter, as does our ability to absorb and use the mineral.
So, does taking a magnesium supplement make sense?
In certain circumstances, yes.
Particularly when our diet doesn’t provide enough, when a deficiency is present or when medical conditions increase the risk of developing one.
But that doesn’t mean we should all start taking magnesium supplements without considering whether we need them.
There are also different forms of magnesium, with differences in absorption and digestive tolerance. High doses can cause diarrhoea and abdominal discomfort, and some supplements can interact with medicines.
Perhaps the question shouldn’t simply be whether magnesium is good for us — because we know it’s essential — but rather: Am I getting enough magnesium, and do I have a specific reason to need a supplement?
Omega-3: Let's Start by Looking at How Much Fish We Eat
Something similar happens with omega-3.
Omega-3 fatty acids are important for our bodies. They include ALA, EPA and DHA, with EPA and DHA found mainly in fish and seafood.
Fish oil supplements can be useful in certain circumstances, and specific doses of omega-3 can help reduce triglyceride levels.
However, the evidence supporting routine omega-3 supplementation for every healthy person is much less straightforward than supplement advertising might lead us to believe.
There’s an important difference between saying:
“Omega-3 fatty acids are important.”
And:
“Everyone needs an omega-3 supplement.”
They are not the same thing.
If we regularly eat oily fish, perhaps our first question shouldn’t be which capsules to buy.
If we rarely eat fish, or have particular nutritional needs, it may be worth looking more closely at our intake and considering whether we need another source.
There are also supplements made from microalgae that provide DHA and, depending on the product, EPA. These can be particularly useful for people who don’t eat fish.
Once again, the starting point is the same: Let’s look at our diet first, then decide what might need supplementing.
Collagen: Perhaps the Supplement with the Best Marketing
I have mixed feelings about this one.
Because collagen isn’t simply a marketing invention.
It’s an extremely important structural protein in our bodies, and researchers have studied whether collagen peptides can benefit certain aspects of skin and musculoskeletal health.
But we shouldn’t imagine that the collagen we swallow travels directly to our wrinkles or knees to “fill them in”.
Like other proteins, collagen is broken down during digestion into peptides and amino acids that the body can use.
So, does taking collagen supplements work?
Perhaps the most accurate answer is: some results are promising, but a great deal depends on what we’re trying to improve and the quality of the evidence.
And this is a particularly good example of why it’s worth looking beyond a headline.
A 2025 meta-analysis found apparent improvements in skin hydration, elasticity and wrinkles when the results of collagen supplement trials were analysed together.
However, when researchers looked separately at higher-quality studies and those without industry funding, the improvements were no longer statistically significant.
Other reviews have reported favourable results for certain aspects of skin and musculoskeletal health, so it wouldn’t be accurate to claim that collagen supplements are completely useless either.
Once again, the reality lies somewhere between the two extremes.
And before turning to collagen powder, there’s something rather basic we shouldn’t overlook: our bodies need enough protein and nutrients such as vitamin C to produce their own collagen.
Once more, I will think about food before supplementing.
Multivitamins: A Nutritional Insurance Policy?
It’s a tempting idea.
I’m not sure whether I’m getting all the vitamins I need, so I’ll take a tablet to cover my bases.
But taking a multivitamin doesn’t automatically turn a poor diet into a healthy one.
When researchers have studied vitamins, minerals and multivitamins for the prevention of cardiovascular disease and cancer in healthy adults without known deficiencies, they haven’t found sufficient evidence to recommend multivitamins for that purpose.
For beta-carotene and vitamin E, the US Preventive Services Task Force specifically recommends against using them for this purpose.
That doesn’t mean a multivitamin can never be useful.
Someone with a highly restricted diet, particular nutritional requirements or difficulty obtaining certain nutrients may be in a completely different situation.
But perhaps we need to move away from the idea that everyone needs a multivitamin simply because life is busy.
A capsule may provide certain micronutrients but cannot replace a good diet.
It cannot give us the fibre in vegetables, the protein in eggs, the fats in fish, the diversity of plant foods or everything we’re still learning about the relationship between food and health.
Probiotics: There Is No Such Thing as Just 'a Probiotic'
This is another particularly interesting area.
We talk about taking probiotics as though they were all the same.
But they’re not.
Probiotics are live microorganisms, and different products can contain different species and strains, in different quantities.
Their effects can also vary considerably.
There are certain situations in which particular formulations have shown benefits.
But for many of the uses we see advertised — ‘improving the microbiome’, ‘supporting immunity’ or ‘improving digestion’ — we still don’t know precisely enough which microorganism, which strain, how much, for how long and for whom.
That changes the question quite significantly.
Instead of asking: “Are probiotics good for us?”
Perhaps we should ask: “Has this particular probiotic been shown to help with the specific problem I want to address?”
And if our aim is simply to look after our gut microbiome, we shouldn’t forget about feeding it.
A varied diet containing fibre and plant foods provides substances that our gut bacteria can use.
Fermented foods can also form part of our diet.
We don’t always need to begin with a capsule.
The Problem with Taking Supplements 'Just in Case'
Perhaps this is the part of the whole subject that interests me most.
We can end up taking five or six different supplements without being entirely sure why we’re taking any of them.
Magnesium because someone recommended it.
Collagen because we’ve reached a certain age.
Omega-3 because it’s good for the heart.
Probiotics because the microbiome is important.
A multivitamin to cover anything we might be missing.
Individually, each decision seems to make some sense.
But when we put them all together, a very simple question emerges: What specific problem are we trying to solve?
If we can’t answer that question, perhaps it’s time to take another look at those bottles.
Because a supplement should have a purpose.
Not just a good reputation.
Do More Supplements Mean Better Health?
Not necessarily. Nutrients perform essential functions in our bodies, but that doesn’t mean that taking increasingly large amounts will provide increasingly greater benefits.
Supplements can also have side effects, duplicate nutrients already present in other products or interact with medicines. Some risks arise precisely because the doses are too high.
That’s why I think we should be particularly cautious about the idea that: “Even if it doesn’t do me any good, at least it won’t do any harm.”
We can’t always assume that’s true.
And this becomes even more important when we’re taking several products at once.
Before Buying Another Supplement, I'd Ask Myself These Questions
We don’t need to turn our diet into a spreadsheet, but a few simple questions can help:
- Why do I want to take it?
- Do I have a known deficiency or a specific nutritional need?
- Could I regularly obtain this nutrient through food?
- Is there evidence supporting this particular supplement for the outcome I’m hoping for?
- What dose am I taking?
- Am I already getting the same nutrient from other supplements?
- Could it interact with any medicines or health conditions?
- Am I taking it for a few weeks for a specific reason, or indefinitely simply because it’s supposed to be healthy?
Sometimes, after answering these questions, taking the supplement will still make perfect sense.
Other times, we may realise that we’re not entirely sure why we started taking it in the first place.
Let's Build a Good Diet First
I think this is where I’d begin.
Before collagen, let’s make sure we’re eating enough protein.
Before omega-3 supplements, let’s look at how much fish we’re eating.
Before magnesium, let’s consider our intake of vegetables, nuts, seeds and pulses — and whether we’re actually getting enough of the mineral.
Before multivitamins, let’s look at the variety in our diet.
And before trying to improve our gut microbiome with a bottle of capsules, let’s think about what we’re feeding the bacteria already living in our digestive system.
After all that, there may still be a place for a supplement.
Of course there may.
Food first doesn’t mean food only.
It doesn’t mean rejecting supplements.
It means giving them the place they deserve.
Conclusion
I don’t think the question is whether supplements are good or bad.
That’s far too simplistic.
Some supplements are extremely useful in certain circumstances. Some deficiencies need correcting. And there are stages of life and medical situations in which supplementation can be important.
There are also people taking a considerable collection of capsules without really knowing whether they need them.
Perhaps, before looking for the next supplement, we should return to something much less fashionable: Our kitchens.
What we buy.
What we cook.
How much variety we eat.
Whether we’re getting enough protein.
Whether vegetables, fruit, fish, eggs, pulses, nuts and other nutritious foods regularly feature in our diet.
And then, if there’s something we genuinely need to supplement, we can do so thoughtfully and for a reason.
Because supplements can be a wonderful tool.
But that’s what they are: A tool.
Not the foundations.
References
- NIH Office of Dietary Supplements. Magnesium — Fact Sheet for Health Professionals. ODs Information on magnesium requirements, dietary sources, deficiency, absorption, supplementation and safety.
- NIH Office of Dietary Supplements. Omega-3 Fatty Acids — Fact Sheet for Health Professionals. ODs Information on dietary sources, EPA and DHA, supplements, cardiovascular health and triglycerides.
- National Center for Complementary and Integrative Health. Probiotics: Usefulness and Safety. NCCIH Evidence on the effectiveness and safety of probiotics for different health conditions.
- U.S. Preventive Services Task Force. Vitamin, Mineral, and Multivitamin Supplementation to Prevent Cardiovascular Disease and Cancer. USPSTF Recommendations on routine vitamin and mineral supplementation for the prevention of cardiovascular disease and cancer in adults.
- Myung S-K. et al. Effects of Collagen Supplements on Skin Aging: A Systematic Review and Meta-Analysis of Randomized Controlled Trials. American Journal of Medicine, 2025. A review examining collagen supplementation, skin ageing and the influence of study quality and funding.
- ANIBES Study (2017). Dietary Intake of Calcium, Phosphorus, Magnesium and Vitamin D in the Spanish Population: Findings from the ANIBES Study. Nutrients. Research examining dietary mineral intake in the Spanish population.
- Guidance for the Determination of Status Indicators and Dietary Requirements for Magnesium. Scientific discussion of the challenges involved in assessing magnesium status and nutritional requirements.