SAMe has been very valuable for me. But I don't see much
improvement with PN.

Here is a long thread (from the past) about it:
http://neurotalk.psychcentral.com/thread5846.html

I stopped it for about 2 yrs recently and my knees flared back up.
So it was working for me, but very slowly for over a decade.

I am back on 400mg a day in the morning on an empty stomach, therefore.

It does improve mood, and so I think that alone helps with pain.

Since people may have mixed arthritis, or psoriatic arthritis, and the compressions from that inflammation may affect nerves, I think it is worth a try. I get my SAMe at Costco. I use Naturemade and they did discontinue the coupon offers, but still Costco has coupons now and then for it in their flyers for members. It is much less expensive today, and compared to the past when they were over $1.00 a tablet (for the 200mg), so that is an incentive to try. I never had any side effects, except for some energizing side effects in the beginning.
People with bipolar are still warned about SAMe, but I haven't seen much in the way of complaints over the years. It is best to take a B-complex, like B-Right with it. After SAMe releases its methyl group it recycles back to homocysteine, so the B-complex helps to keep that down.