There is no supplement product that we are aware of that will alter the color of your teeth...after the event! The products that you are taking along with a good diet will I believe avoid excessive yellowing, but, over time a little bit of 'external' help is needed if you want really bright, white teeth. My suggestion is to have them professionally whitened. I have this done myself about every three years and there is no downside to it as far as I am able to determine. But...it does depend upon the method used. Some dentists sell home bleaching kits which involves putting a gel into a mould and 'biting' into it for a certain period each day. In my opinion these are useless and indeed may be detrimental to your health because you will ingest some of the chemicals that are in the gel.
There are various methods that dentist's use now, laser and 'blue' light being the most common. I have had both. Earlier this year I had my teeth done again with a new technology (Sorry, I am not sure what it is called). The results were great, they have never been so white. I had it done in Thailand where some clinics have state of the art equipment catering to tourists and expats.
What I would suggest is that you research for a clinic in your area that specialises in teeth whitening as it is much more likely that they would have the latest equipment than an 'ordinary' dentist. Talk to more than one clinic with different technologies and weigh up what you feel is the best option. These professional whitening technologies only take about an hour.
Be careful not to drink coffee, cola's or red wine for a couple of days after having it done.