By Michael C Biamonte CCN.

I have come across several websites that market Co enzyme Q10 (CoQ10) and state CoQ10 can help eliminate Candida overgrowth. In researching this further, have found several studies that indicate that CoQ10 actually can cause the colonization of Candida in the upper digestive tract, particularly in cases of low stomach acid or antacid use like Tums, Rolaids etc. I have inserted 2 key references regarding this in this article to allow you, the reader, to examine this for yourself.

Also interestingly enough, I cannot find any reference that would even imply that Co Q10 can eliminate Candida, so I am have not the inkling were the data that it can help eliminate Candida overgrowth originated from.

Here are the notes from the 2 studies;

1. Safety of Ubiquinone
In many large-scale clinical trials, oral ubiquinone has been shown to be safe and efficacious at blood levels of about 4 ppm (considered pharmacologic and attained by 800 mg/day). In addition, even at levels of 80 ppm measured by the Japanese in 1984 with an IV ubiquinone preparation, only beneficial effects were reported. A new injectable liposomal ubiquinone is available from Eisai. A caveat: in patients with alkalinized stomachs, oral Candida can colonize upper gut (potentially lethal); before prescribing ubiquinone, their physicians should study Marshall et al.[39] Our studies show that ubiquinone enhances growth of Candida Albicans.[40]

40. Krone CA, Elmer GW, Ely JTA, Fudenberg HH, Thoreson J: Does gastrointestinal Candida Albicans prevent ubiquinone absorption? Med Hypotheses in press.

2.CAUTION RE CANDIDA. In some people, absorption of supplemental Q10 from the gut may be very low (see FAQ in Langsjoen’s “Introduction…”). We recently conducted a study supporting an Ely hypothesis (see Abstracts 17 and 19 below) that overgrowth of Candida Albicans in the gut may explain this problem. Although no side effects have been found for Q10 itself, certain classes of people who have Candida colonizing the region of gut just beyond the stomach (duodenum and proximal jejunum) are likely to encounter two problems. The orally supplemented Q10 may, all or in large part, be consumed by the Candida preventing the human host from elevating Q10 blood levels and gaining the expected benefits. Of possibly much greater concern is this colonization which, from our recent study of the literature, we fear: (1) can result in high mortality unless corrected promptly; (2) has been recognized since the early 1980’s and identified as a cause of multiple organ failure and other lethal syndromes (Joshi et al 1981; Roy and McCallum, 1984; Marshall et al, 1988);* (3) has gone unread because of both the time pressures on physicians today and the shear size of the 40 million pp/decade of indexed medical science research literature received at our library (it isn’t possible to even turn 40 million pp in a decade); and (4) finally colonization occurs when Candida from the mouth are able to pass thru the stomach because its acid is reduced by any of numerous procedures still common today including over-the-counter proton pump inhibitors and even habitual use of antacid tablets. 
*Joshi SN, Garvin PJ, Sunwoo YC. Candidiasis of the duodenum and jejunum. Gastroenterology 1981; 80: 829-33.
Roy A, McCallum RW. Candidiasis of the duodenum: the role of continuous cimetidine therapy. Gastrointestinal Endoscopy 1984; 30: 47-8.
Marshall JC, Christou NV, Horn R, Meakins JL. The microbiology of multiple organ failure. The proximal gastrointestinal tract as an occult reservoir of pathogens. Arch Surg 1988; 123: 309-315.

CoQ10 is known as a nutrient which increases the potential for oxygen in our cells. Oxygen would be an inhibitor of anaerobic organisms like Candida Albicans so it could be agreed upon that if Co-Q10 increases oxygen it could inhibit Candida. But this is theoretical. The data above in the 2 studies clearly empirically evidence that it aids in the colonization of Candida.