'Too ugly to contemplate' - that was the heading in the news edition email from Crikey.com.au I have just received. I immediately thought it was a news story about someone like me. It fits the way I am feeling perfectly. But of course it wasn't.

And then I had the idea to write about the way I'm feeling. To document this: even though I feel so awful I'd rather just curl up in bed and disappear. I've started writing a work related blog recently and I have received some enjoyment from it, and so I thought I'd try writing about this experience tonight as a way to detach, to get my head out of this space. I have enough wherewithal (and experience) to understand that what I'm going through at the moment is a direct result of the lunch I have eaten. But knowing that doesn't stop me feeling suicidal, it just stops me from legitimising my thoughts as valid, from spending time listing all the reasons why my life isn't worth living, as I once used to do.

I have spent many years experiencing episodes like this and it occurs to me, after "RUOK" day this week, that I haven't seen any information about this particular trigger. I haven't read much about how some people can become profoundly depressed by the foods they have eaten.

I don't want to say which foods set me off, but suffice it to say it's been a long journey to figure it out. I've avoided these types of foods for a while but today was a farewell lunch for a colleague and I wanted to join in with everyone. It was a new restaurant, and I hoped it would be OK.

Within thirty minutes I had the first symptom, which was a dense fogginess in my brain, as though I was barely there, like a zombie, and then I felt a slight head pressure, almost a headache. I knew I was having a reaction to the food but I didn't yet know how bad it was going to be. I haven't had a strong reaction for years. And then two hours later I had the first "what's the point of living, I have absolutely nothing to live for" moment. Within another hour or two rolling fits of blackness came over me; the deep and utter despair, overwhelming feelings of worthlessness and irrelevance and unimportance. I know this will take 36-48 hours to clear my system. I'm glad I don't have much on this weekend.

As I said I have spent many years having episodes like this, through most of my teenage years (if not earlier) and much of my twenties. It was only in my thirties that I heard about food intolerance, as opposed to food allergies, and I tried the elimination diet. I have found that certain chemical numbers and a couple of relatively common food items have a severe negative effect on my mood. There are also other ingredients that affect me which I haven't identified yet, but I know they are in certain sauces so I avoid them just in case. Somehow I have very low motivation to isolate the ingredients to determine which particular chemical is making me feel like I am nothing but a useless, pointless energy sucking black hole on the planet!

I sometimes talk to people about my food sensitivities, and while most people are polite, their response is often one of disbelief. The people who nod vigorously are usually sufferers themselves or they have gone through the process with their children, seeing how they respond to certain foods. It's harder for people who take more than a couple of hours to react to make the link to a certain food ­ for some people it can take days for the symptoms to show, or there are no symptoms until a certain threshold is reached (a little is OK, a lot is not).

There's not any where near enough research done on this.

There is increasing recognition that asthma and eczema are linked to food intolerance/sensitivity, as well as several studies showing that certain foods (particularly additives) can cause hyperactivity, but I have yet to see much research done in terms of foods and links to mood, especially depression. As for me, I'm obviously totally convinced, and I figure if I exist there will be others who have similar food sensitivities, so I thought I'd write about it. I am also allergic to some foods and I have very sensitive skin, so I know there's something about my chemical makeup that makes me sensitive to the world I'm living in.

In general, we know so little about how our bodies react to the world we are living in, and the changes in our food and broader environment have been dramatic in the last few decades. If you suspect this might be relevant for you, I should warn you there is no quick test. Determining your/your children's sensitivities is a long and thorough process but the benefits when everything is sorted are incalculable. – Jude by email