Is there anything I can do to strengthen my immune system? I usually get two or three colds every winter and am keen to try to avoid this.
First, eat plenty of fruit and vegetables — at least five portions a day. This will ensure you get adequate supplies of vitamin C, the antioxidant that keeps your immune system strong.
As I've said before, food is the best source of nutrients such as vitamin C. Even supermarket produce, despite being transported over great distances and then kept in cold storage, still provides enough of the vitamin C and other essential nutrients the body needs.
I never take supplements but make sure I eat lots of good fresh fruit and veg. And if I can't get fresh produce, I'm happy to use frozen because it's picked and packaged so quickly it retains much of its nutrient content.
Frozen ready-meals are not great, but when it comes to berries and vegetables, they're a good alternative to fresh.
When you don't manage five portions of fruit and vegetables a day, and are keen to take a supplement, I'd suggest 250mg of vitamin C, but that's all.
An adult's daily requirement is only 60mg, so this gives you more than enough — the body excretes the surplus. (Children under the age of ten need only 30mg which they can easily get from their diet.)
Larger doses than these can cause gastric upset and stomach bleeding. Some people believe taking large doses of Vitamin C — ie 1-2g — can help stop a cold or flu in its tracks, but I am not convinced the evidence for this is strong.
Source - Daily Mail