Are there any good studies proving that food sensitivities are a real thing?

I was reading this study:

https://pubmed.ncbi.nlm.nih.gov/25786106/

And it found no difference in patient symptoms between aspartame and placebo, thus giving the impression that people with such a sensitivity are imagining things / have psychological issues.

Quite disappointing to me. Considering that I have very consistent symptoms every time I ingest something that contains aspartame in it, which has happened to me dozens of times, sometimes without me knowing I was ingesting aspartame, only finding out after the fact (thus making it unlikely that it is a psychological phenomenon).

Surely there must be some good studies proving that aspartame, MSG, etc. affect certain individuals negatively? Or maybe it's the same situation like CFS, i.e. scientists / doctors thinking its a psychogenic thing and not bothering to research it.

 

I don't know, but at least I haven't had any ME-type disbelief from doctors about the symptoms I get if I eat potato products.

Food intolerance was suggested to me as the most likely cause by the consultant at the gastrointestinal clinic I was referred to, as I'd had sudden-onset severe IBS, but there was no sign of cancer or other serious problems. It still took a while to fathom it, because I didn't realise potatoes were among the foods that can cause it – I assumed that if you aren't allergic to them (and I'm not), they're fine.

 

It's possible that Aspartame sensitivity is rare enough that there weren't any genuine sufferers in the study, may be those included were misdiagnosed. The same thing goes for other sensitivities & allergies.

 

I don't know of any actual studies, but I think it would be hard to prove that food sensitivities do not occur. Our bodies are amazingly complex in their biochemical interactions, so we all have different sensitivities to various chemicals. I was quite sensitive to nightshade toxins (potatoes, tomatoes) at one point in my ME, though I'm less sensitive now. Some people might be insensitive to substances that most people react strongly to. Testing 48 people who claim to be sensitive to aspartame and finding no evidence doesn't mean that some people can't be sensitive to it. If you needed to legally prove sensitivity to aspartame, you'd have to get an expert to test you as an individual.

 

The study you quote looks quite good. From what I have read nobody has been able to demonstrate Kwok's MSG effect either, despite trying. If reasonable studies show nothing then maybe it isn't there?

 

Yes the study was well designed it seems, but one big flaw is the dose they used:

That dose is the equivalent of one 330ml. diet coke. Not much aspartame at all.

When it comes to hypersensitivies we cannot think in a binary manner, there is always a dose-response relationship. Me for example, drinking 330 ml. up to 1l. of diet coke almost never affects me. But when I use an aspartame sugar substitute (which probably contains > 500 mg of aspartame per serving, not sure on exact numbers, have to check later) I always get the same symptoms shortly after.

The study is good, but using only 100 mg to test aspartame hypersensitivity is really not enough.

 

Yes that's very strange. My sensitivities fluctuate a lot. For example now they are a bit better, but a year ago they were terrible. They are not gone though, that's for sure. It seems like the threshold for triggering symptoms has increased (ie. higher dose needed), but the sensitivity is still there.

 

For sensitivities I know something about, its worse than that. Very often the body needs some kind of liver conjugate, or some kind of cofactor for enzymatic activity. One of those is glutathione. Its used to detox many things in the liver, and is a principal regulator of desaturase activity. Salicylates attack desaturases. If the body is deficient in glutathione then its a big problem.Theoretically Its less of a problem if you can raise glutathione levels, but I have not seen a study in which this was tried.

Dysbiosis can play a part too, because gut bacteria detox many things. Desaturases process omega-6 and omega-3 polyunsaturated fats, much of which winds up as a class of hormones called eicosanoids. Some of these have half lives as short as seven seconds. Interupt the supply and it will have an impact on body regulation in seconds.

So not only is salicylate sensitivity dose dependent, its also dependent on a factor probably not measured, namely glutathione.