Absolutely! There is a book called Homocysteine - the best single indicator of whether you live long or die young! (link below) This amino acid in the blood - homocysteine - is the crystal ball of blood tests. A healthy level is 6.3umol/L. If this level is high, this acid is toxic to the body and causes over 100 medical conditions and is the leading cause of heart attack and stroke. Lowering this level to normal shows 49% reduced risk of death from all causes! Vitamin B6, B12 and folate are essential to lower this level so yes B vitamins will help you live longer.
Also, make sure your diet is high in enzymes as you cannot absorb vitamins and minerals or transports the nutrients to every cell in the body. Enzymes are only activated in water, so drink plenty. Low enzyme levels is the root cause of most diseases...including cancer. There are digestive enzymes and systematic enzymes supplements (from health food stores) or you can increase raw foods in the diet (cooked foods have no digestive enzymes).
The Kingdom of Hunza live up to 140 years of age, have never had any incidence of cancer, heart disease, any disease for that matter, no arthritis and every hunzakut has 20-20 vision. Their diet is high in digestive enzymes (raw foods only), they eat a high amount of B17 (this vitamin is banned O_o but is available at the supermarket in fruit seeds, most notably apricot seeds), all the essential vitamins and minerals and their food is completely natural, containing no chemical additives whatsoever.
Vitamin B12 is essential to energy..i know from experience...i slept up to 16 hours a day when very deficient.
The Hunza diet:
http://thepdi.com/hunza_health_secrets.htm
The land of Hunza:
http://www.alkalizeforhealth.net/Lhunzadiet2.htm
Homocysteine - (page 26 goes into how arteries are damaged by homocysteine):
http://books.google.com.au/books?id=o7ZFv772leYC&printsec=frontcover&dq=homocysteine&cd=3#v=onepage&q&f=false
Enzymes:
http://www.healthcoachvideos.com/tag/low-enzyme-levels/