Almost everyone that has gotten ill with CRC (candida related complex) have taken antibiotics in their past. This is the single greatest cause. The other most common ones after that include taking the pill (birth control) and acutane (antibiotic medication used for acne).
After that its likely a variety of factors…most people who are quite ill have slightly damaged livers and thyroid. If you can’t detox properly, then the toxins will build up in the body and make you feel bad. You thyroid is your immune system essentially, so if this gets damaged by lifestyle and/or radiation then you can’t fight off infection.
Then you can get into more alternative concepts such as mercury (from vaccines, fish, fillings, pollution), methylation (breaking down due to gluten and dairy consumption), hypoxia (not enough oxygen in body), pH (relates directly to inflammation and hydration), etc. If you didn’t have inflammation to begin with, then candida will have a hard place to find a home and flourish.