Sunflower seed for laminitis prone pony?

I'm wondering if I can give sunflower seed to my pony? How much? He has about 250kg and doesn't work (only walking, sometimes troting for few minutes).
What about flax seed/linseed?

Would half a cup every other day be too much?

Sunflower seeds are high in Omega 6's which has been shown to promote inflammation so no I would not feed them to a lamantic pony

Flax would be a much better choice

Thank you so much, I didn't know that and this could become dangerous. I'll give him flaxseed :)