Evening Edge

Everyone wants a long, healthy life. We all know that genetic makeup is one key to longevity, but what if you didn't choose your parents carefully and are looking for another way to live longer?

Enter caloric restriction (CR), an idea that has been around since the 1930s when scientists discovered that feeding mice about half of their calorie needs lived longer than the mice given standard lab chow. Studies have shown that other animals, including apes, can extend life by eating less. How does that apply to humans?

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Perusing the Website the "Caloric Restriction Society" (www.calorierestriction.org) it is clear that some people are performing their own experiments by voluntarily restricting calories by 30 to 40 percent of what is recommended by the Dietary Reference Intakes for healthy adults.

Maximum human life span is thought to be 120 years and the proponents of CR hope to break through the life span ceiling. To get the proper amount of nutrients, a CR diet has to be carefully planned to ensure that malnutrition isn't a side effect. Indeed, malnutrition can shorten your life span by weakening your immune system. Some people who follow CR diets call themselves "CRONies," for Caloric Restriction with Optimal Nutrition. The diet is mostly fruits and vegetables with a few whole grains and very little meat.

CR also reduces the production of free radicals — those pesky side effects of metabolism that some think trigger aging effects. CR also helps lower the amount of insulin that your body produces, which could prevent diabetes, and is also linked to maintaining healthy brain cells that could retard neurological diseases like dementia and Parkinson's disease.

Unanswered questions about CR include how severe does the caloric restriction need to be to see the benefits shown in animals? How long do you have to follow the diet to increase longevity? Are the effects only seen during the calorie restriction phase or are there long lasting benefits? One researcher, writing in the Journal of Gerontology, developed a mathematical model on CR and predicted that CR would only extend life by one to five years.

The best strategy is to achieve and maintain a healthy body weight, be active every day, and eat more fruits and vegetables, especially those with deep, rich colors. And, if you are tempted to try CR, remember that the oldest known human lived to be 120 years, and she didn't live a CR lifestyle.