What's the reason for receding hairline and what can I do about it?

There are a couple of reasons:

One is that you have high levels of something called 5 alpha reductase which is an enzyme that converts testosterone into a more powerful form of testosterone called DHT. DHT can burn out your hair follicles.

Second, you have higher androgens, not necessarily caused by having high levels of 5 alpha reductase, they’re simply higher.

You can reduce or inhibit 5 alpha reductase by taking zinc, omega 3, and B2. Zinc is the most important element to ensure you get enough of it. And if you think about it, zinc is also important for your immune system. So if you have alopecia, for example, which is an autoimmune condition then zinc is even more important. You’ll also want to add vitamin D.