I'm a nutritionist and have taken this every day for years:
1 multi vitamin- you don't need an expensive womens formula- I like "Twinlab One-A Day", (with iron if you're still menstrating, without iron if you're past menopause or a male or if you are intollerant to iron).
ALSO,
1000 mg. Vitamin C- I take 1 "Emergen-C" packet a day. This is good to prevent aging, BOOST immunity, fight sun damage, plus many more benfits. You can also get it in a capsule, at a lower cost than the packets.
Women should also take calcium daily (unless you get 1200 mg. from your diet, which is pretty rare). I like the calcium chews. Our body absorbs 500 mg. at a time, so take it in divided doses.
Also, to boost immunity, you should take some probiotics (good bacteria). It helps to fight yeast and infections in the body. Especially if you've had to take antibiotics...you NEED to replenish your good bacteria or you may get repeat infections. Go to your local health food store and buy some probiotic capsules (in the fridge area). Take them in the morning on an empty stomach and wait 30 min. before eating. Take them for 2-4 weeks and then repeat every 6 months or so. You can also eat yogurt a few times a week. That will help too, but the capsules are much more potent than the yogurt.
Also, of course, 8 hours sleep a night and excercise and fresh air is good too. And a positive happy attitude doeesn't hurt either! :)
If you have any questions, feel free to email me.