The supplement industry is enormous, largely unregulated, and filled with products making claims that range from optimistic to outright fraudulent. Walk into any health food shop and you'll find shelves of things with beautiful packaging and almost no evidence behind them.
That said, dismissing all supplementation because some of it is nonsense is also the wrong conclusion. There are a small number of supplements with serious, replicated evidence behind them. For most people eating a plant-rich diet, some of them are genuinely important.
This is our current thinking. It's based on the evidence as it stands, and we'll update it as the science develops.
The non-negotiables
These are the supplements we consider genuinely essential, particularly on a plant-heavy diet.
Vitamin D3 The majority of people in the UK are deficient, particularly between October and March when sunlight is insufficient for the skin to synthesise it. Vitamin D is involved in immune function, bone health, muscle function, and an increasing body of research links deficiency to cardiovascular disease and cognitive decline. The NHS recommends everyone in the UK supplement through autumn and winter. Most people would benefit from supplementing year-round. There is essentially no case against taking this one.
Take D3 specifically, not D2. It's more bioavailable. And take it with K2 if you can, which helps direct calcium to bones rather than arteries. A combined D3/K2 supplement is a sensible choice.
Vitamin B12 B12 is essential for neurological function and red blood cell production. It is not reliably found in plant foods. If you eat a predominantly plant-based diet and you're not supplementing B12, you're taking a genuine risk over the long term. Deficiency develops slowly and is often symptomless until it's serious.
This one is non-negotiable. There is no plant-based dietary workaround. Take it.
Algae-based omega-3 (DHA and EPA) Most people know omega-3 is important for brain and heart health. Most people assume this means fish oil. What fish oil actually gives you is DHA and EPA, the forms your body needs, and fish get those compounds by eating algae. You can go straight to the source.
ALA, the omega-3 found in flax and chia seeds, converts to DHA and EPA in the body, but inefficiently. If you want meaningful DHA and EPA levels without eating oily fish, algae-based omega-3 is the most direct route. The evidence for DHA and EPA in cognitive health and cardiovascular protection is strong and long-standing.
The serious upgrades
These have good evidence and are worth adding once the foundations above are covered.
Magnesium Most people are running low on magnesium. It's involved in over 300 enzymatic processes, including sleep regulation, muscle recovery, and stress response. Modern diets tend to be magnesium-depleted, partly because of soil depletion in industrial agriculture. Magnesium glycinate or malate are better absorbed than the more common magnesium oxide you'll find in cheaper supplements. If you sleep poorly or carry a lot of physical or mental load, this is probably worth trying.
Creatine Long associated with bodybuilding and gym culture, creatine has accumulated a surprisingly robust evidence base for cognitive function as well as physical performance. It's particularly relevant for people eating plant-based diets because creatine is found almost exclusively in meat and fish. Studies suggest benefits for memory, reasoning, and mental fatigue under stress. It's inexpensive, well-studied, and safe at normal doses. Worth considering regardless of whether you train.
Glycine An amino acid involved in collagen synthesis, sleep quality, and cellular repair. It's found primarily in the connective tissue and skin of animals, parts of the animal most modern diets don't include even for meat-eaters. Research on glycine and sleep quality is interesting. Research on its role in longevity pathways, particularly as part of the GlyNAC combination (glycine and N-acetylcysteine together), is emerging and promising. Not a tier-one supplement but worth knowing about.
The ones we'd approach more carefully
General multivitamins Often provide too little of what you actually need and unnecessary amounts of things you don't. Better to address specific deficiencies directly than to take a broad-spectrum product that's mediocre across the board. If you're eating a varied, whole-food diet and covering the above, a multivitamin is unlikely to add much.
High-dose antioxidant supplements The idea that more antioxidants is always better has not held up particularly well in clinical trials. Some high-dose antioxidant supplements have shown neutral or even negative effects in certain populations. Getting antioxidants from food - berries, colourful vegetables, herbs and spices - remains the most clearly beneficial approach.
Most "longevity" supplements NMN, NR, resveratrol, and others are genuinely interesting areas of research. Some of the science, particularly around NAD+ precursors, is compelling in animal models and early human trials. But the evidence in humans is still limited and the products are expensive. We'd watch this space rather than spend heavily on it now.
How we think about this at BOSH!
The Daily 8+2 framework places supplementation in the "+2" tier, alongside reducing ultra-processed food. The point of that positioning is deliberate: supplements are optimisation on top of a good diet, not a substitute for one.
No supplement will undo a poor diet. But if you're eating well, training, sleeping, and managing stress, closing the remaining nutritional gaps with a small, evidence-based stack makes sense. The four we'd start with are D3, B12, algae omega-3, and magnesium. Everything else is worth considering once those foundations are solid.