While fighting candida is good, at least part of the problem might be parasites. If you haven't done a parasite cleanse lately, then I recommend that you do one. Also eat plenty of raw garlic, and take vitamin A(the palmitate, not beta carotene) 10,000-20,000 units a day. vitamin A is important in general immunity, and in fighting parasites. Many with parasites have been found to have a vitamin A deficiency. Perhaps enough people can't properly convert beta carotene to vitamin A? Smokers are advised not to take large doses of vitamin A though, as I saw an article about a study saying that large amounts of vitamin A increased the smokers incidence of lung cancer. Don't take more than 20,000 units of vitamin A a day long term, as this can lead to toxicity. Perhaps a dosage of 20,000 units a day for a while(for those who might be deficient), then a scaling back to 10,000 units a day might be a good idea.

This is all interconnected. mercury, a weakened immune system, parasites, poor absorbtion of some nutrients, candida overgrowth, etc.

It is also important to get enough calcium and magnesium.