My wife is a well-regarded and experienced psychotherapist, and the first thing she does with every client experiencing depression is initially advocate a 'clean' diet of regular un-processed food, daily time outdoors and exercise (even just mild to begin with) and an increase in 'mindfulness' or guided, objective self-observation. This is before she even engages in actual treatment regimes. Without exception, her clients report marked improvements and an increased willingness to embrace whatever treatment regime or changes are agreed for the long term. As she is an integrative psychotherapist, her overall approach is geared to individual circumstances rather than a prescriptive method, but in EVERY case, she advocates clean, regular diet, outdoor exercise and mindfulness. Her track record would suggest it's pretty effective. The report cited here comes as no surprise at all.