I rapid cycle anywhere between 8 to 10 times a day. From my experience, there are three ways to control the frequency and intensity of your cycling:
1) Having a good sleep cycle - Bipolars are more likely to cycle faster when they have improper circadian rhythmn...
2) Diet - Multi-vitamins can be a good choice, because many of us are deficient in essential minerals, and omega-3s are also good supplements. Avoiding alcohol and nicotine are also a good idea, as they tend to have adverse affects on biochemistry.
3) Managing your triggers... i.e. STRESS. Stress will invariably worsen the intensity and frequency of symptoms is nearly every medical condition, as it weakens our defenses and can often send our biological processes into over-drive.
Hopefully these can be useful to you...