As a lot of you will now, my Dh battled with depression for years and has at least been free of it (in the full on suicidal sense he was anyway) since 2004. I also grew up with a severely depressed Mother.
I think that there are lots of factors to depression.
Tiredness, especially in this day and age, in a huge contributor imo. getting Dh's sleep patterns sorted (a vicious circle with depression as that itself causes sleep disorders) was a huge contributor to his recovery, as was time off work and medication.
A break from his family wa also important, as they do affect his wellbeing: thinking about it his last episode (a mild one) was a year ago exactly: when his dad ran off with another woman.
Do I think diet is a factor? Oh definitely. Dh would go for ages eating a pot noodle every day and 2-3 bags of crisps a day. Like many men, healthy eating just menat not getting fat to him (he's 5'10" and was 9.5 stone- he's gained a stone now).
I made him look closely at his diet, it's not perfect now but he takes an apple or banana to work, drinks loads of water (it used to be coffee 12 X a day, linked to his night work) and cooks food in thhe steamer with loads of veg. yes he still does the junk, but nothing like before.
I think if you're vulnerable for whatever reason, then ill health is a risk factor, and a poor diet is going to contribute to that. I DO NOT think it is a substitute for medication when needed- I had to sit through someone slating depressives who took medication rather than deal with themsleves the other day. Yes OK there may be a few, but after DH's experience, and the friend I was with lost her son and brother to suicide- well, medication or death? Hmmmm.
I really think that depression is not a thing caused by any one thing, but a cumulation. Sleep, diet, lifestyle, self esteem, life events- they all have their part to play, and research that identifies that (albeit in this case cse studies I believe? may be wrong) has to be welcomed. Especially given the diets we used to feed our Psychi patients when I was nursing.
And about the people on low incomes- so right, sadly. I sat with a Mother (I was on placement with a HV) with PND who claimed she couldn't leave the house because she was too fat. She was big yes, not massive. I talked her through the whole healthy diet thing- explaining she could grill her bacon, eat porridge, it was as much as anything a case of looking at how you cook as eating different food- she just looked at me and said 'are you trying to deny me my only pleazsure then?'.
And at homeStart we used to offer the kids healthy foods at suport group. Well, we DID- first few months I was there- then I got sick of the Mums saying 'nah he won't eat that' and pushing it away (usually whilst Junior was grabbing at it hungrily). the others and I all gave up in the end, we just did the biscyuits and squash thing. We knew some kids didn't get fed anything else until tea time (group was 9.30, the kids would come then get chips and curry sauce at dinner).
I say, give any rises in cild benefit in the form of fruit and veg vouchers. Yes, some parents will sell them for drug money but I think it wpuld help a lot. Five pounds extra week in fruit and veg tokens for everyone on income support from tomorrow please Tony- 99.9% of the Mums I know will be glad of them and use them appropriately.
Sorry, this subject is a soapbox of mine!! I apologise.