Yeast-free challenges

The best way to overcome food intolerances is to remove them from your diet for a period of time, then slowly reintroduce them one by one and monitor the effects. I have an intolerance to both dairy and yeast, and have tried to eradicate them from my diet.
Dairy appears in different forms in many processed foods, but there are good alternatives, and as a recognised allergen, food packaging is pretty helpful.  Yeast, however, is rarely highlighted. On the surface, it should be pretty easy to avoid - cut out bread and doughnuts, wine, beer and cider. Apart from cider, I used to enjoy all these things with great gusto, but I've learnt to manage without, although its so tempting at times, especially wine and bread when you're on holiday in France!
Recently though, I realised I pay more attention to avoiding dairy than yeast, even though I know it's a big issue. Dairy gives me terrible head and neck aches that easily develop into migraines if not caught early enough. Yeast has a more insidious effect, gradually building up producing a multitude of seemingly random effects including restless legs, fatigue, headaches (different ones), itchy skin, dry eyes and (to the family's delight!) terrible bloating and wind! It's not going to kill me but it makes me feel so grotty at times, it really does have a negative effect on my life.
We all have various yeasts and bacteria in our bodies; our guts are alive with its own little eco-system that helps to keep our bodies healthy and balanced. Problems start, though, if that balance is upset; the not so friendly bacteria can start taking over and yeast becomes overgrown, eventually working it's way into the gut lining and allowing undigested food proteins and bacteria to seep through into the blood stream. This can lead to food allergies, amongst a long list of other problems. To get rampant yeast under control, it needs to be avoided food wise, the over growth eradicated and the gut eco-system restored to a healthy balance.
So step one, avoiding yeast, is easier said than done. It is more than just leaving out the bread and wine. For a start, yeast is a mould, so moulds in general need to be avoided. Not that I have a habit of eating mouldy food, or not obviously mouldy anyway, but it appears in many places, including anything fermented.
This includes ingredients such as soy sauce, over ripe or dried fruit, vinegars of all kinds, miso and malted anything.  Then there's stock cubes, Marmite (yuck!), pickle, mayonnaise - the list goes on!
Now I've tried to avoid many of these for some time now; some of the nasty effects from yeast have subsided, but some have not and others just keep reappearing.

So I decided to look into yeast and moulds in food a little bit more, and it didn't take long to make a huge, and rather disappointing discovery. Many of the 'natural' food flavourings and preservatives found in processed foods are made from cultured yeasts and moulds! The particular one that stood out to me was citric acid, a preservative and stabiliser that appears in hundreds of different food products, including simple items such as tinned tomatoes, tomato puree, tortilla wraps and flat breads - in fact many of the substitute foods I use!
I always thought that citric acid was a natural derivative of citrus fruits. A weak organic acid with a sour, acidic flavour, it is a natural preservative. Historically, Italy was the main producer of citric acid, formed from their huge citrus fruit harvests. Supplies were disrupted during the First World War but by this time a biochemist had discovered a yeast that grew on a sugary medium that produced citric acid, and so this replaced the natural fruit source. Citric acid is still a 'natural' preservative, but one that's manufactured! Today, 1m tonnes of citric acid is produced this way every year, and demand is so high it wouldn't be economical or practical to get citrus acid from fruit - there's just not enough of it to meet demand.
Natural flavourings and other preservatives are created in similar ways, so we are all inadvertently eating yeasts and moulds, although for most people this is not a problem. However, for myself and many others, it is and I'm disappointed I didn't realise this before. There's so much to learn about food science! If I really want to get to the root of my yeast intolerance, it seems I have to make absolutely everything from scratch, including my flat breads and tomato sauce. Convenience foods are suddenly absolutely inconvenient!