According to the Swedish Food Agency, children and most adults should consume at least 10 micrograms of vitamin D per day, rising to 20 micrograms per day for over-70s as well as people who rarely have sun on their skin. For the following groups, it recommends taking 10 micrograms of vitamin D supplements per day (you may also see supplements measured in IE, in which case 10 micrograms is equivalent to 400 IE). People with little or no exposure to the sun, who also don’t eat fish or food with added vitamin D.