The British Vitamin D problem is not new.
Britain sits between 50 and 58 degrees north. London is on the same latitude as Calgary. Edinburgh is level with Moscow. From October to March, the sun does not rise high enough above the horizon for the UVB wavelength your skin needs to actually reach the ground. You can stand naked in February noon sunlight on the south coast and produce essentially zero vitamin D.
This is six months of the year, every year, for the entire history of human habitation on these islands.
The British have known this, in their bones, for ten thousand years.
Look at what was eaten in winter, before anyone had ever heard the term cholecalciferol:
Oily fish. Herring, mackerel, sprats, kippers. Three or four times a week from October to March. A single kipper carries roughly 250 IU of D3.
Cod liver oil. Spooned into every British child between 1850 and 1980, a teaspoon at a time. Distributed free by the Ministry of Food in the war on the explicit understanding that British children needed it through the dark months. Rickets fell by 90 per cent between 1940 and 1960. Cod liver oil was the reason.
Liver. Eaten weekly in working households until 1985.
Egg yolks from hens that had been outside in the summer.
Grass-fed butter, made from cream from cows on summer pasture, the fat-soluble vitamins banked into the cream and eaten through the winter.
The British solution to the British problem, evolved over centuries by people who could not articulate the biochemistry but knew, with absolute certainty, what kept the children growing through the dark months.
Then between 1955 and 2010, the British removed almost all of them.
Cod liver oil reduced to a niche supplement. Liver dropped from weekly to never. Oily fish consumption halved. Eggs rationed by the Department of Health on cholesterol grounds since retracted. Butter replaced with margarine carrying no fat-soluble vitamins at all.
Result, by 2020: roughly half of all British adults are vitamin D deficient by the end of winter. A third of children. Rickets has reappeared in British paediatric wards. The NHS now recommends every adult take a supplement from October to March.
This is the NHS recommending in 2026 what the British diet was doing automatically in 1926.
The geography has not changed. The latitude is the same. The sun is still inadequate from October.
The food used to handle it.
The kippers are still being smoked at Craster. The cod liver oil is on the chemist's shelf. The liver is at the butcher. The butter is in the dairy aisle, behind the spreads.
The sun was always seasonal.
The food was the backup.
The backup got thrown out.
Get it back.