You're spending £80/month
on supplements. Most of it
you could get from food.

Vitamin D3 is the only supplement we consider near-universal for UK adults - not because the supplement industry says so, but because the data is unambiguous. The UK's latitude means meaningful UVB exposure (the wavelength needed for D3 synthesis in skin) is only reliably available from approximately late April to September, and only when the UV index is above 3. Between October and March, it is essentially impossible to synthesise adequate vitamin D3 from sunlight in the UK.

Public Health England recommends 400 IU daily. Most vitamin D researchers consider this inadequate - optimal blood levels (75–125 nmol/L) typically require 2000–4000 IU daily for most adults, though this varies with body weight, skin tone, and existing deficiency levels.

K2 must accompany D3. Vitamin D3 increases calcium absorption, which is beneficial for bone density. But without vitamin K2, this calcium can deposit in arteries rather than bones - potentially increasing cardiovascular risk. K2 (specifically MK-7 form) acts as the traffic director, ensuring calcium goes to the right places.

Magnesium is involved in over 300 enzymatic reactions in the body - including protein synthesis, muscle function, blood glucose control, blood pressure regulation, and nerve transmission. It's also a natural calcium antagonist, meaning it supports muscle relaxation and is closely linked to sleep quality.

UK dietary surveys consistently find that a significant proportion of adults consume less than the recommended daily amount. Modern agricultural methods have reduced the magnesium content of vegetables and grains compared to 50 years ago, making adequate dietary intake increasingly difficult.

Avoid: Magnesium oxide - poorly absorbed (only ~4% bioavailability). It's the cheapest and most common form in budget supplements. If your supplement doesn't specify the form, it's likely oxide.

The eight B vitamins work together to convert food into energy, maintain nervous system function, produce red blood cells, and support cognitive function. B12 and folate (B9) are particularly important and commonly deficient in specific populations.

Vitamin C is a water-soluble antioxidant essential for immune function, collagen synthesis (skin, joints, blood vessels), iron absorption, and wound healing. Unlike most animals, humans cannot synthesise their own vitamin C - we must obtain it from food daily.

The good news: vitamin C is abundant in a wide range of foods and genuine deficiency (scurvy) is rare in the UK. However, suboptimal intake is common in people eating few fruits and vegetables, and athletes may benefit from higher intake due to increased oxidative stress from training.

A single red bell pepper delivers 200mg of vitamin C - five times the NHS RDA. If you eat a varied diet with plentiful vegetables, supplementation is largely unnecessary. However, buffered vitamin C (calcium ascorbate) is gentler on the stomach for those supplementing at higher doses.

Important: Do not supplement iron without confirming deficiency through a blood test (ferritin level). Iron toxicity is a real risk - excess iron is pro-oxidant and stored in tissues. Iron supplementation should be targeted, not prophylactic, unless advised by a GP. Iron-deficiency anaemia affects approximately 1 in 5 menstruating women in the UK - it's worth testing if you experience persistent fatigue.

Omega-3 fatty acids - specifically EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid) - are the anti-inflammatory counterbalance to the omega-6-dominant Western diet. The UK average omega-6:3 ratio is approximately 15:1–20:1; optimal is closer to 4:1 or lower.

EPA and DHA are found primarily in oily fish. If you're not eating salmon, mackerel, sardines, herring, or anchovies at least 2–3 times per week, a quality fish oil supplement is one of the most evidence-supported supplements available.

Quality matters: Look for fish oil with IFOS certification (International Fish Oil Standards) or similar third-party testing. Rancid fish oil is pro-oxidant. Smell it - if it smells strongly of fish, it's likely oxidised. Refrigerate after opening.

Caution: Vitamin A (retinol) is fat-soluble and can accumulate to toxic levels. Unlike most vitamins, more is not better - and supplementing vitamin A directly is rarely necessary for most people eating liver or eggs. Pregnant women should not supplement pre-formed vitamin A (retinol) above 700 mcg/day due to teratogenic risk. Discuss with your GP.

Beta-carotene (from orange and dark green vegetables) is converted to vitamin A by the body as needed - it's the safer, self-regulating dietary source and is generally preferable to direct retinol supplementation.