Flat footed people please help

[ZenKaleidoscope]

I'm trying to choose some sandals for my brother who is flat footed. He says that he wasn't born with flat feet but because of wearing cushioned shoes his arch collapsed...aparantly this makes a difference...I don't quite understand why.

So with the below sandals which type would be best? Rubber or leather? Thicker or thinner?

We are both struggle to understand which would be better. Thanks

www.etsy.com/uk/listing/1150831421/barefoot-leather-sandals-running?click_key=85491d7855fcb1daab05b5675d1021cb47caa79c%3A1150831421&click_sum=5dac3ee0&ga_order=most_relevant&ga_search_type=all&ga_view_type=gallery&ga_search_query=zero+drop+minimalist+shoes&ref=sr_gallery-1-2&organic_search_click=1&frs=1&bes=1&sts=1&variation0=2413584215

Flat feet are generally caused by unsupported shoes. So you generally want something cushioned and supportive especially around the arch. The sandles you have linked have no arch support at all and could potentially make his condition worse and painful as once the arches have fallen it can lead to over pronation of the foot which can cause plantar fasciitis. I'm a physiotherapist and have worked with many flat footed patients with plantar fasciitis (I too suffer myself) and arch support is needed. I hope that helps.

Or there is an alternative view that wearing shoes like Vivo barefoot shoes, as unstructured as possible, force the foot to work all its muscles and regain a correct foot shape.

My feel look different after six months of wearing these, my toes are spaced out instead of being crushed together, my feet are stronger, my legs are more toned and my knees no longer turn inwards. So I am a fan!