Is vipassana meditation an effective way to reduce stress?

Yes: Lots of research has shown that vipassana and other forms of meditation are effective ways to deal with stress and its effects on the body.

Yes, vipassana: Vipassana is also known as "insight" or "mindfulness" meditation, and is the basis for the research-based program called "mindfulness based stress reduction." this is an 8 week-long, skills training program that can be applied to many stress-related conditions. It has been shown effective in many research studies. A sample here: http://www.Ncbi.Nlm.Nih.Gov/pubmed/23541163.