There are many contributors to yeast overgrowth and your case may involve one or more of the following: poor nutrition, antibiotics (that we have taken and also in the foods we eat), birth control pills, chemical pollution, hormonal changes (pregnancy, menopause), compromised immune system, corticosteroids, chlorinated water, chronic constipation, stressful lifestyle.

From “Conquering Yeast Infections, the Non Drug Solution for Men and Women” by S. Colet Lahoz,
“CRC is a side effect of modern medicine. Since 1950 “the increasing use of antibiotics, contraceptive hormones, and immunosuppressant drugs in medical practice has encouraged the growth of this yeast in many individuals.” These drugs disrupt the flora balance in the intestines.

Faulty nutrition feeds yeast overgrowth. In addition to the glut of sugar we knowingly eat in the form of refined sugar products such as doughnuts, ice cream, candies, cakes, cookies, soda pop – many people don’t realize the hidden sugar content in foods, condiments and beverages.
Refined sugar feeds the fungi allowing them to proliferate; it is addictive and over consumption is the norm; it causes an imbalance in the acid/alkaline levels, wreaks havoc with the sugar/insulin blood ratio (causing physical stress), and increases the physical need for vitamins and minerals.

“Another dietary factor is regular consumption of poultry, meat, and milk. The animals from which we get these products have been treated with antibiotics and hormones that are then passed on to the consumer of the meat or milk, thus destroying good bacteria in the gut of the consumer. Chemical preservatives present in many foods also encourage CRC.

Low bulk, highly-refined carbohydrate diets also help establish a breeding ground for yeast. This diet slows the peristaltic action of the colon (the washing machine-like movement of the colon). A sluggish colon builds up layers of fecal matter in the large intestine. This layering results in putrefaction, fermentation and rancidification of old ingested food, which is a perfect home for Candida albicans. On this diet, the small intestine becomes clogged with mucous which promotes the growth of fungus.” From Conquering yeast Infections, the Non Drug Solution for Men and Women” by S. Colet Lahoz.

Compromised Immune System. A system weakened by poor nutrition, lack of sleep, constant stress, environmental pollution, the use of drugs, depression, trauma, loss, is often a causative agent of CRC.
Other factors that can significantly weaken the immune system include:
Alcohol and/or drug abuse
AIDS
Cancer
Chemotherapy/radiation
Diabetes
Hypothyroidism
Liver disease
High mercury levels (from dental work)*
*Mercury can inhibit necessary bacterial growth in the intestines. Many health practitioners believe that many health problems are caused by mercury leaking from fillings into the bloodstream.