My good friend and Nurse has put a lot more Avocado into my diet claiming it lubes the joints. I have found some relief with Capsaicin creme applied directly to my knees post MCL tear. But mostly knee discomfort is just a part of getting stronger on your bike. As you progress you will experience bouts of knee discomfort. Also, and I see it all the time, keep your feet straight with the bike. This imposes the least possible stress on your knees. You don't notice while riding because you are warmed up but, post ride it creeps in and the next thing you know you are posting knee pain problems. Heating pad, followed by ice bags will promote blood flow for quicker healing. 95% of supplements are "Snake Oil" and only line the pockets of the makers. Real food has all the extra substances to help you digest and use the nutrients. A well balanced diet provides everything you need. Remember to " eat many colors" and try and limit "Red Meats" and Sugar. Sodas and highly processed foods are the enemy. Look up the ten foods everybody should avoid. Best thing I ever did was get off those.