I am 72 years old and have had sharp pains in my knees for quite a few years when going down stairs, and lately have been developing some of the pains of developing Arthritis. My friend suggested taking 2000 MG of this supplement for 10 days and then 1500 MG after that. So, I decided to take her advice and try it. I swear, after the 10 days, there was no more pain in my knees. One night I took a full 2-gallon watering can and a 1 gallon bottle of water downstairs at the same time and held on to the railings anticipating pains in my knees - there was no pain!! Since then, there has been no pain in my knees and they feel stronger. I later found out with some research that Ester-C helps to build joint tissue and can help to reduce the pain of Arthritis. This seems to hold true since the stiffness in my finger has lessened since I have started using this supplement. I take a few supplements, but I have honestly not come across any other supplement that showed any results so quickly. I am a believer in this one, and it is good for much more than the immune system. The only downside I can think of is the size of the pill. It's huge, and it sometimes takes me a couple of tries to swallow it. I am also giving this supplement to my 98-year-old mother, but for her, we crush it and add it to her supplement cocktail. UPDATE 11/24/18: I have been taking Ester-C for 2 months, and the pain in my knees is completely gone as well as the shakiness I used to have in my knees when I went down stairs. I have also noticed that my finger joints are no longer locked when I get up in the morning, and the sharp pains I had in one of my fingers has not been happening. I can't say that this supplement helps with Arthritis, but I have definitely had some improvement with joint pain and locking of finger joints. UPDATE 10/18/19: I have been taking Ester-C for a little over a year, and the benefits described above are still evident. Although i still use this supplement for my 99 year old mother who gets it pulverized in a vitamin supplement, I had a hard time swallowing the huge pills. So, I found another brand that still provides 1000 mg but in a capsule. The capsule works as well for me, but I don't gag trying to swallow it. I hope this review was helpful for you. I will update the review if my opinion changes