Longecity is a forum for people who want to become immortal. Sounds pretty /x/-related to me. They have a whole section just for supplements, check it out.
http://www.longecity.org/forum/forum/6-supplements/
It's difficult to find scientific articles on the pineal gland, but this comes pretty close in my opinion.
https://skillcode.com/pineal-gland-science/
Basically, avoid eating junk food, meditate, and practice fasting. The most effective type of fasting is, of course, water fasting. Juices are to be avoided as they contain too much sugar. As a general rule, the longer you fast, the greater the benefits, but it also depends on your physical condition. If you're really skinny and you fast for a week, your body is going to consume its own muscle tissue because there's no fat to use as fuel.
For most people, it's okay to fast 3 days a month. That means 3 days in a row, because that's the time it takes for your body to go into autophagy mode, where it kills the old and damaged cells and substitutes them with new ones. This process has been shown to improve mental faculties and reduce the risk of dementia. During these 3 days only water can be consumed.
It's important to remember that your first meal after a fast should be small, because by then your digestive system has been inactive for 3 days. Start with a yogurt, some fruits, and gradually move to more substantial foods.
Omega-3 fatty acids are important for your brain to work properly and to reduce inflammation in your body, among other things. The problem is that many modern foods contain omega-6 acids, and this has disrupted the balance between omega-3 and omega-6. This page has lots of good information, but I suggest avoiding fish because these days the sea is too polluted. In my opinion the best source of omega-3 is flax seeds.
https://draxe.com/omega-3-foods/