First, I have no idea if the supplements help. Maybe they do, maybe they don’t. I don’t have enough knowledge to say either way.
Second, Horst is incentivized to say that they do work. He sells the product.
Again, maybe it helps, maybe it doesn’t. But biases should always be taken into account, so his claims should be discounted purely because the bias is present. If you’re curious, it would be best to read the original study (and find out what the study’s designers and sponsors do for a living) and/or ask an impartial nutritionist.