Mari R, I had been dealing with Candida for 4 months, following the low sugar diet your friend is on WITHOUT SUCCESS (that diet only helped somewhat), and when I finally started searching deeper, I found better things that really make sense and are helping significantly (since applying them in the last 2 weeks).
The first thing was finding an even better diet. The 80/10/10 diet (Low Fat Raw Vegan, aka 'fruitarian') immediately started improving my symptoms (which had waned on the low-sugar diet but were forever coming back).
If you search around, you'll find lots of testimonials of extreme candida sufferers who got better on the 80/10/10 diet - I bet your friend will feel immediately better, just from that change alone.
In other words: the strict low-sugar diet helps (vs. most other diets), but the strict 80/10/10 diet is still even better, and in addition it is much more satisfying (IMO).
Stay away from juice and smoothies though! Fresh fruit & veggies is NOT juice, or juicing, or smoothies, all of which speed up sugar and nutrient absorption too much (which feeds the microbes more than yourself, one of the core aspects of candida infections).
However, whereas the 80/10/10 diet doesn't seem to be particularly keen on fermented foods (without being against it), I would say they are key to the best health and important when candida is a problem. (I therefore kept eating lots of delicious home-made kimchi)
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The other bit of info that is really interesting is to consider *why* someone would reach a point where they are no longer omnivorous, and instead display increasingly limited digestive ability.
So obviously, MMS is one thing to do to help heal one's digestive system, but another thing is what is called a 'liver flush', where you basically help your liver flush out the thousands of nasty stones that accumulate and end up blocking the liver's ducts.
I found many testimonials about how liver flushes were also key in recovering 100% from systemic candida infections (ex: going back to being able to eat and live 'normally').
The thing with liver flushes though is that you typically need to do 6-8 of them (sometimes more) to get all the stones out, since each flush pushes out just a few hundred stones, with 3-4 weeks rest between each flush.
The gentlest, most effective and most popular 'liver flush' seems to be Andreas Moritz'. His book
The Amazing Liver and Gallbladder Flush
is really well worth reading (pro-tip: google for the book title + 'pdf' to get a copy of an older edition, in case you'd like to check it out before buying).
In any case, search for 'liver flush candida' testimonials and you'll find plenty of people who solved their cases completely. I did my first flush last weekend and got about 50 little stones out, but I know I have plenty more to do (the big stuff typically comes out in later flushes).
Where 80/10/10 ties back to candida is like this: if the bile ducts of your liver and gall bladder are blocked, then you are not able to properly digest anything really other than fresh fruit and salad (low fat). The good news though is that by adopting the 80/10/10 diet you remove nearly all strain from your digestive system, which makes it easier to deal with MMS and/or liver flush side effects, as minor as they generally are.
My own liver flush felt fine, but some people feel ill when they release previously blocked toxins, or if they don't follow all the steps (like the strongly recommended colon hydrotherapy, or its many alternatives).
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One liver flush detail for your friend: the book suggests replacing the apple juice with malic acid tablets when you have candida, since otherwise the juice's sugar is bad (especially since it should be taken on an empty stomach). I made sure to work out every day (at least 25 min), which made it so my muscles absorbed the excess sugar, so personally I was able to take the 1L apple juice a day without it affecting my (relatively minor) candida symptoms - but I was already on the 80/10/10 diet at that point, FWIW, and apparently such a diet also makes your cells better able to absorb sugar in general.
Anyhow, good luck to your friend! I'll try to come back here for an update once I'm done with the liver flushes, but I am also going to being doing MMS since it looks so promising, and since Andreas Moritz also recommends it (he mentions MMS being able to potentially cure vitiligo, I imagine by helping to remove the poisons that are stopping the skin from behaving normally - I hope that will work for me too!).