Being a vegetarian and hanging around in so-called "alternative", "crunchy", and even "New Age" circles has brought me some interesting experiences over the years. I remember a time nearly everyone I knew who frequented the local health foods shop was convinced they suffered from a body-wide yeast overgrowth, about 15 years back — after talking to the owner of the shop, who "had systemic candidiasis" herself. They then, of course, "had to" turn to yeast infection treatment at home to cure themselves.
Just as the wave of systemic Candida began suddenly in my social circle, it simply went away at some point. The same people later discovered other things, things like reiki and colloidal silver, and Candida was never mentioned again. The same isn't true for everyone — all that stands between some people and the conviction that they have systemic Candida is a Google search.
Systemic Candida is indeed a real thing, but it's nothing like what my sisters believed they suffered from.
What Is Systemic Candidiasis?
Systemic candidiasis, also called acute disseminated candidiasis or invasive candidiasis, can be diagnosed when a person's, eyes, brain, heart, bones, and other vital body parts are infected with Candida species. The blood can also be infected with Candida, in which case it's called candidemia.  Though many Candida species can be responsible, only five species cause 90 percent of all these infections — Candida albicans, Candida glabrata, Candida parapsilosis, Candida tropicalis and Candida krusei. 
Invasive candidiasis is commonly associated with hospitalization — an estimated 46,000 healthcare-related cases are diagnosed in the US alone on an annual basis, with candidemia being the most common form of invasive candidiasis. How do you get it? The jury is still out on that one. The Candida that normally lives on your skin and in your gastrointestinal tract may enter your blood stream if you receive a central catheter, or the infection may be caused by contaminated medical equipment or passed on via a healthcare provider's hands. [3, 4]
We do know that some people have a higher risk of developing invasive candidiasis:
- Those who have a central venous catheter.
- Intensive care unit patients.
- People who have recently taken broad-spectrum antibiotics.
- People with kidney disease.
- Those who have recently had surgery, particularly in the gastrointestinal region.
- Diabetics. 
- Individuals with weakened immune systems, like cancer patients , very low birth weight infants , and people who are HIV positive .
What Are The Symptoms Of Invasive Candidiasis?
The symptoms of invasive candidiasis depend on the parts of the body that have become infected. They may include:
- The symptoms of septic shock — a rapidly beating heart, fast, labored breathing, and hypotension — in patients with candidemia.
- Fever and chills that aren't resolved by a course of antibiotics.
How Is Invasive Candidiasis Treated?
Invasive candidiasis is treated with IV antifungal medications, such as echinocandin, fluconazole, amphotericin B. It's then followed up with antifungal regimens until the symptoms completely resolve and Candida is no longer present in the affected organ(s) or the blood stream. This is a multi-week affair. 
How is invasive or systemic candidiasis not treated? That's right — with a "Candida diet"! Keep in mind that invasive candidiasis is still a potentially life-threatening infection that also makes one feel rather ill. It's not something to mess around with.
There is evidence that cutting sugars from your diet helps prevent the formation of Candida biofilms, structures formed by the yeast that make treatment more difficult, if you suffer from invasive candidiasis . There is some evidence that taking probiotics, taking multivitamin supplements, and using propolis can reduce one's risk of vaginal or oral yeast infections.  There is even evidence that vaginal creams with garlic, boric acid capsules, tea tree oil, and coconut oil may be viable home remedies for a yeast infection.
There is certainly no evidence that a "yeast infection diet" alone clears up actual invasive candidiasis — just like there is no evidence that the people I mentioned above actually had invasive candidiasis. In conclusion, systemic candidiasis is indeed very real and certainly not the figment of quacks' imaginations, but that doesn't mean that quacks don't diagnose invasive candidiasis where none exists. Before you believe you have systemic candidiasis, remember that it makes you quite ill — usually when you are already quite ill to start with — and that it can only be diagnosed with the help of lab tests.