Vitamin d3 for vegetarian teens?

[LaValliere]

I take a daily liquid vitamin d3/k2 supplement, 4000 iu/25mcg. My middle son (15) has recently become vegetarian & I’m wondering if he should take some too. But what would the daily dose be? (He’s over 6 foot & growing if this is relevant.)

Would a better option for him be a general vitamin supplement? If so is there a liquid anyone can recommend (my understanding is that liquids are better absorbed- happy to be corrected if this is wrong)?

I think we all need a vitamin d anyway in the uk during winter. I take k3 with it.

For vegetarians is it b12 that is most needed? I’m not sure.

You can have vitamin D sprays, which are absorbed by the mouth mucosa. 1000 to 2000 per day is a typical dose.
If he needs more supplements will depend on what he eats, not what he avoids, so a diet rich in vegetables, legumes, mushrooms, fruits, whole grains and the other non-plant (fish? dairy ? eggs?) foods.
If relying on 50-shades-of-beige diet with pizza-pasta-chips-cookies, yes he might need more.