Most people have a reasonable sense of which foods contain Vitamin C or calcium. Fewer have a clear picture of where B vitamins, selenium and iodine actually come from in a typical UK diet. This guide is an attempt to make that more concrete.
The B vitamin family in food
B vitamins are spread across a wide variety of foods, but the distribution isn't uniform. B12 stands out as the one that occurs almost exclusively in animal products - meat, fish, eggs and dairy. For those who eat little or none of these, reliable B12 intake from food alone becomes genuinely difficult. B6 is more broadly available: it appears in poultry, fish, potatoes, wholegrains and bananas. Niacin (B3) is found in meat, fish, wholegrains and peanuts. Pantothenic acid (B5) is present in almost all foods in small amounts, with higher concentrations in offal, sunflower seeds and mushrooms.
The practical implication is that a diet centred around varied whole foods - particularly if it includes some animal products - will cover most of the B vitamin family reasonably well. Gaps appear most often with B12 in plant-based diets, or in diets that are heavily processed and low in variety.
"B12 occurs almost exclusively in animal products. For those who eat little or none of these, reliable intake from food alone becomes genuinely difficult."
Selenium: a UK-specific consideration
Selenium is an interesting case because the UK's relationship with it has changed over time. Until the 1980s, the UK imported large quantities of wheat from North America, where soil selenium levels are considerably higher than in the UK. As imports shifted toward domestically grown and European wheat, average dietary selenium intake fell. The foods that still provide meaningful selenium in the UK are Brazil nuts (highly variable), offal, fish and shellfish. For those who don't eat these regularly, selenium can be quietly low.
Iodine: dairy, fish and the gaps in between
Iodine in the UK diet comes primarily from dairy products and white fish. Milk and yoghurt are the single largest contributors for most people, which means that those who reduce or avoid dairy - whether for preference, intolerance or dietary choice - often see their iodine intake drop without realising it. Iodised salt, which provides a backstop in many European countries, is not widely used in the UK in the way it is elsewhere. Seaweed contains iodine but in highly variable and sometimes excessive amounts, making it an unreliable source for consistent daily intake.
Where gaps tend to appear
A few eating patterns consistently produce nutrient gaps in population-level data: plant-based or vegan diets (B12, iodine, selenium); diets low in variety or heavily processed (multiple B vitamins); diets that have recently shifted - perhaps following a change in circumstances, budget or routine. None of these is unusual, and none is a reason for alarm. It is simply useful to know where you stand. A short, focused supplement can serve as a practical backstop for specific nutrients - not as a replacement for the food-based approach, but as a complement to it.