Are Supplements Really Necessary? A Functional Medicine Practitioner's Honest Answer
- Juliana O’Boyle IFMCP
- 3 days ago
- 12 min read
Juliana O'Boyle IFMCP · June 2026
A friend of mine recently relayed a conversation she'd had with someone who had told her, quite confidently, that supplements are a waste of money. That we should be able to get everything we need from food. That the whole industry is essentially a well-marketed con.
I understand why people say this. There is a lot of noise in the supplement space, a lot of products that don't deliver what they promise, and a lot of well-meaning but oversimplified advice circulating online. The scepticism is not entirely without basis.
But as a Functional Medicine Practitioner with over fifteen years of clinical experience, I find this view genuinely concerning — not because I want to defend an industry, but because I see the consequences of unaddressed nutritional deficiencies every week in clinic. And the blanket dismissal of supplements as unnecessary is, in my experience, doing real harm to real people.
The truth, as with most things in health, is considerably more nuanced.
The Food First Principle — And Why It Isn't Enough When Supplements Are Necessary
Let me start by saying something that might surprise you: I agree with the food first principle. Wholeheartedly. A nutrient-dense, varied, mostly whole food diet is the foundation of good health, and no supplement protocol will compensate for a poor one.
But here is the problem. The idea that a good diet reliably provides everything the body needs is based on an assumption that is increasingly difficult to sustain: that the food we eat today contains the same nutritional value it once did. It doesn't.
Decades of intensive farming, soil depletion, the use of pesticides and herbicides, selective crop breeding for yield rather than nutrition, long supply chains, extended storage and food processing have all contributed to a significant reduction in the nutrient density of many commonly eaten foods. Studies comparing the nutritional content of fruits and vegetables today with those from fifty years ago have found meaningful reductions in minerals including magnesium, iron, zinc and calcium — not because we are eating differently, but because the food itself has changed.
This does not mean food has no nutritional value. It means the argument that "you can get everything you need from a good diet" is more complicated than it sounds — and should be made with considerably more caution.
Why Absorption Explains Whether Supplements Are Necessary
Even setting aside the question of what is actually in our food, there is a second layer to this conversation that is almost never discussed outside of clinical practice: the difference between consuming a nutrient and actually absorbing and utilising it.
Digestion is not a passive process. Nutrients require adequate stomach acid, digestive enzymes, bile production, a healthy intestinal lining and a well-functioning microbiome in order to be properly broken down and absorbed. When any of these components are compromised — and in my clinical experience, compromise is far more common than people realise — nutrient absorption is affected, regardless of how good the diet is.
Low stomach acid, which becomes increasingly common with age and stress, impairs the absorption of B12, iron, calcium, magnesium and zinc. Intestinal permeability affects how efficiently nutrients cross the gut wall. Dysbiosis — imbalance in the gut microbiome — can impair the synthesis of certain B vitamins and vitamin K. Digestive enzyme insufficiency means that even well-chosen foods are not fully broken down.
This is why I rarely look at nutrition in isolation. A client can be eating an exemplary diet and still present with significant deficiencies — not because their food choices are wrong, but because their gut is not absorbing what they are eating. Addressing gut function is often the first step, but targeted nutritional support is frequently necessary alongside it.
When Are Supplements Necessary? Life Stages and Increased Demand
There are also specific life circumstances and health conditions in which nutritional demand increases significantly — sometimes beyond what even an excellent diet can reliably meet.
Perimenopause and menopause bring shifting hormonal dynamics that increase the body's requirements for nutrients involved in bone health, energy production, nervous system function and mood regulation. Magnesium, vitamin D, B vitamins, omega-3 fatty acids and calcium all become increasingly important during this transition.
Chronic stress depletes magnesium, B vitamins and vitamin C at a rate that diet alone rarely compensates for. The adrenal glands have particularly high nutritional demands during periods of sustained stress.
Pregnancy and breastfeeding significantly increase requirements for folate, iron, iodine, omega-3s, vitamin D and choline — nutrient needs that are well-established and universally recognised, yet rarely achievable through diet alone.
Digestive conditions — including IBS, inflammatory bowel conditions, low stomach acid and a history of antibiotic use — all compromise absorption and can lead to clinically significant deficiencies over time.
Certain health conditions directly affect how nutrients are metabolised or increase requirements for specific micronutrients. These need to be assessed and addressed individually.
In each of these situations, the advice to "just eat well" is not wrong — it is simply insufficient on its own.
Medications That Deplete Nutrients — A Conversation That Rarely Happens
One of the areas I feel most strongly about, and one that is almost never discussed in mainstream healthcare, is the relationship between commonly prescribed medications and nutritional depletion.
Many medications routinely interfere with the absorption, metabolism or utilisation of specific nutrients. This is not a fringe concern. It is well-documented in the pharmacological literature. Yet patients are rarely informed of it, and the nutritional consequences are rarely monitored or addressed.
A few of the most clinically relevant examples:
Proton pump inhibitors (PPIs) — widely prescribed for acid reflux and stomach ulcers — significantly impair the absorption of B12, magnesium, iron and calcium. Long-term use without nutritional monitoring is, in my view, a significant clinical oversight.
Metformin, commonly prescribed for type 2 diabetes and increasingly for other conditions, depletes vitamin B12 — a deficiency that can cause nerve damage, fatigue, cognitive changes and mood disturbance if unaddressed.
The oral contraceptive pill depletes B vitamins including folate and B6, as well as magnesium, zinc and selenium. Women who have been on the pill for years and then experience difficulty conceiving, low mood or fatigue are often unaware that nutritional depletion may be a contributing factor.
Statins interfere with the body's production of CoQ10, a nutrient critical for cellular energy production and cardiovascular function — which is particularly ironic given that statins are prescribed for heart health.
Corticosteroids deplete calcium, magnesium, vitamin D, zinc and B vitamins with prolonged use.
If you are on any long-term medication and have not had a conversation about its nutritional implications, it may be worth raising with a suitably qualified practitioner.
Why Most Supplements on the Market Aren't Necessary — Or Effective
Here is where I will give some ground to the sceptics — because they are not entirely wrong.
A significant proportion of the supplements available in high street pharmacies, supermarkets and online retailers are, frankly, not worth taking. Not because supplementation itself is ineffective, but because supplement quality varies enormously and the consumer has almost no way of knowing the difference without specialist knowledge.
The issues I see most commonly:
Poor bioavailability — the form of the nutrient used determines how well it is absorbed. Magnesium oxide, for example, is one of the most commonly used forms of magnesium in cheap supplements, yet it has very poor bioavailability compared to magnesium glycinate or malate. The label says magnesium. The body receives very little of it. The same principle applies across many nutrients — the form matters as much as the dose.
Inadequate dosing — many standard supplements contain doses too low to have any meaningful clinical effect, particularly when addressing a deficiency or supporting a specific health condition. A standard multivitamin may contain a token amount of a nutrient that looks reassuring on a label but does little therapeutically.
Unnecessary fillers, binders and additives — many commercial supplements contain titanium dioxide, artificial colours, hydrogenated oils, allergens and other unnecessary ingredients that have no business being in a health product and which can, in sensitive individuals, cause problems of their own.
No third party testing — reputable supplement manufacturers subject their products to independent testing for purity, potency and the absence of contaminants. Many mass-market products do not. What is on the label is not always what is in the capsule.
Interactions and contraindications — certain supplements interact with medications or are contraindicated in specific health conditions. High-dose vitamin E and fish oil, for example, can affect blood clotting. St John's Wort — widely available over the counter — has significant interactions with several medications including antidepressants and the contraceptive pill. Taking supplements without this knowledge is not harmless.
This is precisely why supplement quality and practitioner guidance matter so much — and why the answer to poor quality supplements is not to stop supplementing, but to supplement properly.
Why Practitioner Supplements Are Necessary for Real Results
The supplements I use and recommend in my practice are not available on the high street. They are formulated specifically for clinical use, prescribed by practitioners who understand both the mechanisms and the individual they are working with. The differences are meaningful:
Bioavailable forms — practitioner brands use nutrient forms that are selected for absorption and clinical efficacy, not cost. Methylated B vitamins for those with MTHFR gene variants. Magnesium glycinate for nervous system support. Liposomal vitamin C for enhanced absorption. These are not marketing terms — they reflect real differences in how the body can utilise these nutrients.
Therapeutic dosing — doses are calibrated to achieve a clinical outcome, not simply to meet a label requirement or avoid regulatory scrutiny.
Minimal excipients — clean, well-formulated products contain as few unnecessary ingredients as possible.
Third party tested — reputable practitioner brands test independently for purity and potency.
Used within a clinical context — the supplement is one part of a wider plan that takes into account the individual's health history, symptoms, medications, gut function and specific deficiencies. It is not a product being sold. It is a therapeutic tool being applied precisely.
This distinction matters enormously. A methylated B complex prescribed for someone with a known MTHFR variant who is experiencing fatigue, low mood and cognitive fog is an entirely different clinical intervention from a standard B complex purchased speculatively from a supermarket shelf.
Why Supplements Are Only as Necessary as the Guidance Behind Them
I want to be direct about this, because I think it is one of the most important points in this article.
Supplementation without proper assessment is guesswork. And guesswork with physiologically active compounds is not without risk.
A qualified practitioner — one with a genuine understanding of nutritional biochemistry, mechanisms and clinical application — does not simply recommend popular supplements or follow a generic protocol. They:
Assess before prescribing — using clinical history, symptom patterns, dietary analysis and where appropriate functional testing to identify what is actually needed, rather than what is fashionable or generally recommended.
Understand mechanisms — knowing why a nutrient is needed, how it is absorbed, what cofactors it requires, how it interacts with other nutrients and medications, and what forms are clinically appropriate requires a depth of knowledge that goes well beyond reading a product description.
Personalise the protocol — two people with the same symptoms may need entirely different nutritional support depending on their gut function, health history, life stage, medications and underlying drivers. There is no universal protocol.
Monitor and adjust — a good practitioner does not simply prescribe and disappear. They review how the body is responding, adjust doses and formulations as needed, and reassess as health improves.
Know when not to supplement — equally important is knowing when supplementation is not the right approach, or when it needs to be preceded by other interventions such as improving gut function, addressing diet or reducing medication load.
The qualifications to look for when seeking this kind of support include registration with a recognised professional body — in the UK, relevant bodies include the Institute for Functional Medicine (IFM), the British Association for Nutrition and Lifestyle Medicine (BANT), the Association of Naturopathic Practitioners (ANP) and the British Herbal Medicine Association (BHMA). Postgraduate qualifications in nutritional medicine, functional medicine or naturopathy are relevant. As with any area of healthcare, experience in clinical practice matters as much as academic credentials.
Are Supplements Really Necessary? A More Honest Answer
If someone tells you that supplements are a waste of money, what they are often really describing is one or more of the following: a low quality product, an inappropriate supplement for their individual needs, poor absorption due to an unaddressed gut issue, the wrong form or dose, or the absence of the clinical context that would make the intervention meaningful.
None of those things mean supplementation doesn't work. They mean it wasn't done well.
The food first principle is sound. Eat as well as you possibly can. Prioritise dietary diversity, whole foods and regular meals. Address the foundations of health. These things matter enormously and no supplement replaces them.
But for many people — and I would argue for most people at some point in their lives — targeted, well-formulated, clinically appropriate nutritional support is not a luxury or a wellness trend. It is a meaningful and sometimes essential part of supporting health.
The key word is targeted. Not speculative. Not generic. Not based on what your friend is taking or what you read online. Based on you. Your body. Your history. Your needs right now.
Frequently Asked Questions
Are supplements really necessary if I eat well?
For some people in good health, with excellent digestion, low stress and no medications, a nutrient-dense diet may well be sufficient for basic nutritional needs. But this describes relatively few people — and even then, certain nutrients are difficult to obtain in adequate amounts from food alone. Vitamin D is an obvious example in the UK, where sunlight exposure is insufficient for much of the year. Omega-3 fatty acids, iodine and magnesium are others where dietary sufficiency is far from guaranteed. The honest answer is: it depends entirely on the individual — their diet, their gut function, their life stage, their health history and their specific needs right now. That is why assessment matters more than generalised advice.
Why do some people not feel any benefit from taking supplements?
This is one of the most common things I hear, and it is almost always explained by one of a handful of reasons. The supplement may be using a poorly absorbed form of the nutrient. The dose may be too low to have any meaningful clinical effect. The supplement may not be addressing the actual underlying issue — taking B12 does not help if the reason for low B12 is an unaddressed absorption problem. Or the gut itself may be too compromised to absorb the supplement effectively. Not feeling better from a supplement is useful clinical information — it is not evidence that supplementation doesn't work. It usually means something else needs to be investigated first.
What is the difference between practitioner supplements and those bought in a pharmacy or supermarket?
The differences are significant and go well beyond price. Practitioner-quality supplements use bioavailable forms of nutrients — the forms the body can actually absorb and utilise — rather than cheaper alternatives that look identical on a label but deliver far less to the cell. They use therapeutic doses calibrated for clinical outcomes. They contain minimal unnecessary fillers, binders or additives. And they are subject to independent third-party testing for purity and potency. Perhaps most importantly, they are prescribed within a clinical context — as part of a personalised protocol informed by assessment, not selected speculatively from a shelf.
Can supplements interact with medications?
Yes — and this is one of the most important reasons to work with a qualified practitioner rather than self-prescribing. Several commonly used supplements have clinically significant interactions with medications. St John's Wort, for example, is widely available over the counter yet interacts with antidepressants, the contraceptive pill and several other medications. High-dose fish oil and vitamin E can affect blood clotting. Certain minerals compete for absorption with medications if taken at the same time. A practitioner with a proper understanding of drug-nutrient interactions will always review medications before making recommendations — and will time supplementation appropriately to avoid interference.
How do I know which supplements I actually need?
The honest answer is that without proper assessment, you don't — and neither does anyone else. Nutritional needs vary enormously between individuals based on diet, gut function, life stage, health conditions, medications, genetics and symptoms. What works well for one person may be unnecessary or even counterproductive for another. A qualified practitioner will take a thorough clinical history, assess symptoms, review diet and medications, and use functional testing where appropriate to identify genuine deficiencies and imbalances. The result is a targeted, personalised protocol — not a generic supplement stack based on what is currently trending.
What qualifications should I look for in a practitioner who recommends supplements?
Look for postgraduate qualifications in nutritional medicine, functional medicine or naturopathy, alongside registration with a recognised professional body. In the UK, relevant bodies include the Institute for Functional Medicine (IFM), the British Association for Nutrition and Lifestyle Medicine (BANT), the Association of Naturopathic Practitioners (ANP) and the British Herbal Medicine Association (BHMA). Clinical experience matters as much as credentials — understanding how nutrients behave in a living, complex person is very different from academic knowledge alone. Be cautious of anyone recommending a supplement protocol without taking a thorough clinical history first.
Juliana O'Boyle IFMCP, MSc, AMH, ANP is a Functional Medicine Practitioner, Herbalist, Naturopath and Nutritionist with over 15 years of clinical experience. Through her Functional Herbalism approach, she combines the science of functional medicine with the wisdom of herbal medicine to help women uncover the root causes of digestive, hormonal and energy-related symptoms. Juliana holds an MSc in Personalised Nutrition, is certified through the Institute for Functional Medicine (IFM), and works with clients across the UK through her West London-based practice, Functional Herbology.
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