The Truth About Supplement Quality – What Supplements I Recommend and Why

For more than two decades, my career has been dedicated to understanding how nutrition impacts human health, particularly the eye and the brain. Through my work at the Nutrition Research Centre Ireland (NRCI) and, more recently, with Supplement Certified, I have spent much of my professional life trying to answer a deceptively simple question: When we take a supplement, how do we know what we’re really getting?

The supplement industry is vast and growing. Walk into any pharmacy or health food shop, and you’ll find shelves lined with bottles promising support for everything from heart health to memory, energy, and vision. But here’s the uncomfortable truth: most supplements on the market do not contain what they claim on the label.

In fact, my own research has shown that up to 70% of eye health carotenoid supplements we tested failed to match their label claims. That means when someone buys a supplement in good faith, often recommended by their GP, optician, or pharmacist, they may not actually be getting what they paid for.

This reality is what drove me to co-found Supplement Certified, an independent testing and certification programme that verifies whether supplements really contain what they say they do. In this article, I want to share what I’ve learned about supplement quality, explain why it matters so much, and give you practical guidance on the supplements I recommend – and why.

Why Supplement Quality Matters

Supplements are not prescription drugs. They are regulated as foods, which means the bar for testing and quality control is far lower. In most countries, including Ireland, it is essentially a self-regulated industry.

That means if you or I wanted to launch a supplement tomorrow, we could source raw materials, send them to a contract manufacturer for encapsulation and labelling, and then put that product on shelves with minimal oversight. We’d need to notify and provide documentation to the Food Safety Authority, of course, but there is no mandatory requirement for independent verification of the actual product.

This lack of oversight leads to three main problems:

• Label claims don’t match reality: The nutrient listed on the label may be present in smaller amounts, in unstable forms, or not at all.
• Stability issues: Even if the product is correct at the point of manufacture, nutrients may degrade during storage and transport, leaving the consumer with little or nothing active by the time they take it.
• Consumer trust is undermined: People invest their money and their health in supplements, believing they are doing something good for themselves. When the product doesn’t deliver, not only is that a waste, but it could also compromise long-term health.

Imagine you go to the supermarket to buy a carton of 12 eggs. You bring it home, open it, and discover only eight inside. You’d be frustrated and probably go back to the shop. But with supplements, you can’t see inside the “carton.” You’re forced to trust that what’s claimed on the label is really there. Unfortunately, far too often, it isn’t.

The Birth of Supplement Certified

The idea for Supplement Certified emerged from a surprising discovery during one of our clinical trials. We were measuring carotenoids (nutrients found in foods like spinach, peppers, and egg yolks that are important for eye and brain health) in the blood of trial participants.

To our surprise, we found a carotenoid present in their blood that was not listed on the supplement label. Initially, we thought there had been a mistake. But after extensive checking, we confirmed the truth: the supplement contained an ingredient not declared on its packaging.

This opened a “can of worms.” We began to question just how widespread this issue might be across the supplement industry. The answer, sadly, was that it was very common.

That discovery was the spark that led to the creation of Supplement Certified. Our mission is simple: to test supplements independently and certify those that contain exactly what they claim, both at the point of manufacture and throughout their shelf life.

Today, Supplement Certified works with companies across Ireland, the US, and Europe. Our labs operate under ISO-certified procedures and are subject to independent audits to ensure full integrity. We provide independent verification that products are stable, authentic, and trustworthy. Consumers can look for the Supplement Certified logo on packaging as reassurance that what they are buying has been rigorously tested.

How Supplements Should Be Evaluated

Whenever I’m asked about what supplements I recommend, I always emphasise two critical points:

• Clinical Evidence: A supplement should be backed by well-designed, peer-reviewed human clinical trials that demonstrate its efficacy. If a product claims to improve vision, protect against macular degeneration, or support memory, there should be published data to support those claims.
• Independent Certification: Even if a supplement is clinically proven in theory, you need to know that the product you buy contains the same formulation tested in the research. That’s where independent verification, like Supplement Certified, becomes vital.

Over the past 25 years, my research has focused on two key groups of nutrients that have a significant impact on eye and brain health: carotenoids and Omega-3 fatty acids. These compounds have been central to my clinical trials and studies, revealing how they protect the retina and support brain, eye and heart health.

Carotenoids for Eye and Brain Health

Carotenoids are plant pigments found in colourful fruits and vegetables, particularly dark green leafy vegetables and bright red or yellow produce. Three specific carotenoids – lutein, zeaxanthin, and meso-zeaxanthin – form a protective pigment in the eye called the macular pigment.

This pigment acts like “internal sunglasses,” filtering harmful blue light and protecting the retina from oxidative damage. Higher macular pigment levels are linked with better visual performance (contrast sensitivity, glare reduction, faster recovery from bright light) and a lower risk of age-related macular degeneration (AMD).

But these carotenoids don’t just benefit the eye. Research now shows they also accumulate in the brain, where they are linked with better cognitive function and memory.

Omega-3 Fatty Acids (DHA & EPA) for Brain, Eye, and Heart Health

Omega-3 fatty acids, particularly DHA (docosahexaenoic acid) and EPA (eicosapentaenoic acid), are essential for human health but cannot be produced by the body in sufficient amounts.

DHA is a major structural component of the retina and the brain. Adequate levels are vital for vision and cognitive health.

EPA plays a key role in reducing inflammation and supporting cardiovascular health. While omega-3s can be obtained from diet (fatty fish like salmon, mackerel, or sardines), most people do not consume enough regularly. Supplements provide a reliable way to achieve optimal intake.

My Recommendations

• ReMind (Europe) / MemoryHealth (USA): A high-quality, independently certified omega-3 supplement containing 500mg DHA and 150mg EPA per daily dose. ReMind was one of the first omega-3 brands to commit to the Supplement Certified programme and has also been tested in NRCI clinical trials.
• MacuPrime (Europe) / MacuHealth (USA): This NRCI clinically tested, and Supplement Certified formula contains all three macular carotenoids in an optimal balance proven to support eye and brain health. Its independent verification ensures that the nutrients listed on the label are exactly what’s in the bottle.
• VitroCapN: A German eye health supplement, Vitrocap is also tested and certified through Supplement Certified. Key bioactives and stability are verified to provide independent reassurance that the product meets quality standards.

Supplements That Are Supplement Certified

Key: LMZ = Lutein, Meso-Zeaxanthin, Zeaxanthin; DHA = Docosahexaenoic Acid; EPA = Eicosapentaenoic Acid; Vit C = Vitamin C

What I Do Not Recommend

Equally important as knowing what to take is knowing what not to take. I do not recommend supplements that:

• Make exaggerated or unrealistic claims (“miracle cures,” “instant results”).
• Lack published clinical trials on the actual supplement formulation (borrowed science).
• Have not been independently tested for quality.

Remember: in the current regulatory environment, the burden is on you, the consumer, to distinguish between genuine science and marketing hype.

The Future of Supplement Regulation

One question I am often asked is whether governments should do more to regulate supplements. My answer is yes.

At present, the industry is effectively self-regulated. While agencies like the Food Safety Authority of Ireland do important work on checking on labelling health claims, there is no requirement for independent quality testing to confirm the supplement contains what it says on the label. That needs to change.

I’ve spoken directly with government representatives about this. The way I see it, it’s like asking people to pay road tax but telling them they don’t have to if they don’t want to. Some will comply in good faith, but many will not. The only way to truly protect consumers is to make independent testing mandatory.

Until then, organisations like Supplement Certified exist to fill that gap, helping responsible companies demonstrate their quality and giving consumers confidence in what they buy.

The supplement world is full of both promise and pitfalls. On the one hand, certain bioactive nutrients – like carotenoids, omega-3s, and vitamin D – can make a profound difference to our long-term health. On the other, too many products on the market are unverified, unstable, and ineffective.

My advice is straightforward:

• Choose supplements backed by clinical research.
• Look for independent certification.
• Be wary of exaggerated claims.

As a scientist, my goal has always been to translate research into real benefits for people, helping them see better, think more clearly, and live healthier for longer. Supplements can play a role in that journey, but only if we demand the same standards of quality and transparency that we expect from every other product we consume.

If you’d like to learn more, you can visit Supplement Certified

Or explore my ongoing research and publications here on my website.

Let’s protect consumers, reward quality companies, and ensure supplements fulfil their true potential: helping us all live healthier, better lives.

I recently discussed some of these insights during an interview on WLR FM’s The Hot Desk , where I spoke about how to identify quality supplements and what to look for when choosing them.

For transparency, this blog mentions supplements (Supplement Certified, MacuHealth, MacuPrime, ReMind, and VitroCap) I’ve been directly involved in researching and consulting with. You can read my full Disclosure Statement for more details.