At some point in life, most women experience the unpleasant symptoms of yeast infection.  The organism responsible for the majority of yeast infections, Candida albicans, is normally present in the body in small but harmless amounts.  Under certain conditions, however, yeast multiplies rapidly and causes unpleasant symptoms.

Anything that disturbs the normal balance of yeast and bacteria in the body can create the ideal conditions for yeasts to start growing uncontrolled. 

When the immune system is weakened by illness, stress or a lack of sleep, the body is more prone to react upon fungi.  The risk is also increased by hormonal changes during pregnancy, by the use of birth control pills or by diabetes.

Taking antibiotics can lead to yeast infections for these agents not only kills the bacteria causing the illness, but also the “friendly” bacteria that keep yeast levels balanced.

Foods likely to contain yeasts and moulds

Yeast extracts such as Marmite, Oxo, stock-cubes, etc.
Yeast is also in bread (but not in proper soda bread), yeast pastries and pizza.
Fermented products including natural vinegar (except white "spirit vinegar" which is purely chemical) pickles, sauerkraut, ketchup and soy sauces contain yeasts.
All alcoholic drinks involve yeast fermentation.
Yeasts grow well in fruit juices, honey, syrups and molasses.
Cheaper vitamin supplements may contain yeast and selenium supplements are often yeast based. 
Black tea involves fermentation, but green tea does not so would be a substitute for black tea.
All cheese contains moulds.  Blue, brie and very mature hard cheeses have the most.
Moulds are involved in the spoilage of fruits, berries and vegetables.
Dried fruit may contain molds on the skins. 
Left-over foods grow moulds, less in the freezer than in the fridge.
Mushrooms are moulds and should also not be eaten.
Molds may be present on crops of peanuts, dry beans, and cereal grains.  Its toxin is called aflatoxin and can cause illness and death.

Dietary treatment

There are quite a number of foods that should be avoided, but you do not have to go hungry.
As far as possible, cut out refined carbohydrates, especially sugar, foods containing yeasts and foods containing moulds.
Left-over foods should be avoided.
All fresh vegetables (leaves, stalks and roots), fresh herbs, and fresh fruits classed as            vegetables (tomatoes, cucumbers, green peppers, etc.) are allowed.
It is very important to wash fruit and vegetables very well to rid them of any yeasts or molds that might be on the skins.
Fruit juice should be used with caution because it contains a high percentage of sugar which supports the growth of fungi, but fresh fruit can be eaten up to two a day.
All fresh meats and fish are allowed, but not ham.
Avoid any alcohol.
Eggs are allowed and so are all milks, other than sweetened condensed milk.
Yogurt, especially natural bio-yogurts, can be used.  The “friendly” bacteria keep yeast levels in check.