Not medical advice. I am not a doctor or dietitian. This is what I learned from reading the NHS page, written down in plain English. For advice about your own health, speak to a GP, pharmacist or registered dietitian.
Photo: @schneiderhenry / Unsplash
It is October, which is when the NHS vitamin D advice becomes relevant, so this is the post I most wanted to write. Here is what the NHS page says.
What it does
Vitamin D helps regulate the amount of calcium and phosphate in the body, and both keep bones, teeth and muscles healthy. The NHS says too little can cause rickets in children and osteomalacia, which causes bone pain, in adults.
Where it comes from
- Sunlight. From about late March or early April to the end of September, the NHS says most people can make all the vitamin D they need from sunlight on bare skin outdoors. From October to early March, the sunlight does not provide enough.
- Food. Few foods contain it. The NHS names oily fish, red meat, egg yolks, fortified foods such as some fat spreads and breakfast cereals, and liver. It says cows milk in the UK is generally not a good source because it is not fortified.
- Supplements. The third source, and the one the advice below is about.
The autumn and winter advice
Because the sun is too weak in autumn and winter, and food alone rarely provides enough, the NHS advises everyone to consider a daily supplement of 10 micrograms (400 IU) during those months. You may choose not to take one from late March or early April to the end of September. Some people are advised to take 10 micrograms all year round, such as people who are rarely outdoors or who usually cover most of their skin outside, and the NHS page lists the groups, including babies and young children, in detail. I am not going to try to summarise that list for you; please read it on the NHS page.
The warning about too much
Taking too many supplements over a long period can cause hypercalcaemia, an excess of calcium in the blood, which can weaken bones and damage the kidneys and heart. The NHS says 10 micrograms a day is enough for most people and gives an upper limit of 100 micrograms (4,000 IU) a day for adults. It lists lower limits for children and babies, and says people with certain medical conditions may need to take less. If in doubt, ask a doctor.
What I have not found out yet
I do not know yet how much time outdoors is enough in a Welsh summer, and the NHS page does not give a figure, so I am not going to invent one. The page also shows a review date of August 2020, so I want to check it against the current guidance. If you want advice about your own vitamin D, ask your GP or pharmacist.