HuffPost Review: How to Live Forever

So -- is it nature or nurture? Do people live to be 100 because they took exceptional care of themselves or because they are lucky enough to have good genes?

That's part of the question at the core of Mark Wexler's amusing and eye-opening documentary, How to Live Forever. Wexler checks in with both experts and actual centenarians, examining a variety of theories and practices about aging, how to do it gracefully and whether, in fact, a human being can actually do something to prolong and enhance their sunset years.

Wexler says right from the start that he was provoked to look into the subject by the death of his mother and his own 50th birthday (and the arrival of his first issue of AARP magazine). So he headed out to talk to everyone from Jack LaLanne to Suzanne Somers, from gerontologists to philosophers, looking at the differences in diet and exercise that contribute to longevity.

And he makes a distinction between long life and longevity, defining the latter as not just the number of years one lives but also the ability to be actively enjoying those last years.

There do seem to be differences by culture. A scientist who has studied the elderly on Okinawa notes that the residents' diet is rich in fish and vegetables. As a result, the average Okinawan experiences an average of two and a half years of disability at the end of life, compared to seven years for the average American.

Wexler is a good enough sport to try a variety of things on camera, at the urging of his subjects. He works out with the late LaLanne (who bursts into song at one point). And he allows himself to be mechanically lowered into a coffin at a Las Vegas convention of funeral directors.

He finds a variety of people who offer their own take on why they've been able to stay vital into their 90s and 100s. These include a 75-year-old Japanese man who, late in life, became a star of "elder porn." Almost as amusing: a 100-year-old Brit named Buster Martin, who still worked washing vans for a plumbing company. Buster, who died in mid-April, nearly steals the film, with his talk about the fact that he still runs marathons (and takes breaks along the route to have a beer and a cigarette).

That's the conundrum that Wexler comes up against: that, for every still-active 90-year-old Okinawan living on fish and seaweed, there's a 120-year-old French woman smoking Gauloises, drinking wine and eating chocolate. And for every Suzanne Somers, espousing questionable facts about hormone therapy, there's a Jack LaLanne, touting the power of exercise and eating fresh, raw food.

But Wexler himself seems comfortable with not getting a definitive answer. Instead, he offers food for thought -- and How to Live Forever makes you think, even as it has you chuckling.