In the 1930's it was found that laboratory animals fed a calorie-restricted diet lived longer and had a lower risk of cancer, diabetes and cardiovascular disease, but until now, there has been little evidence to suggest that calorie restriction diets extended human lives.
Researchers at the Salk Institute for Biological Studies in La Jolla, California, have identified a gene in roundworms that directly links calorie restriction to a longer lifespan.
The research team led by Andrew Dillin say a gene called pha-4 plays a role in gut development in embryonic worms, but in adults is associated with calorie-restricted longevity.
However Mr Dillin also says it is unclear whether similar genes may play a similar role in humans but humans do have three genes very similar to the worm's pha-4.
These genes say the researchers are related to glucagon, a pancreatic hormone that increases blood sugar concentration and maintains the body's energy balance, particularly during fasting.
The researchers say the pinpointing of the worm gene might lead to drugs being developed that imitate the effects of calorie restriction and could allow people to live longer without following a severely restrictive diet.
Mr Dillin says whether dietary restriction will increase longevity in humans is unclear but they are now testing the diets on monkeys.
As Mr Dillin says some people are actively doing this voluntarily; he says it usually takes a 50 to 70 per cent reduction in normal food intake to yield longer lifespan in animals but if food is reduced too much and leaning towards starvation that would make life shorter.
Dietary restriction says Mr Dillon is one of the universal forms of increasing longevity and this has been shown in everything ranging from yeast all the way up to dogs.
The report is published in the current issue of the journal Nature.
Closing the Choline Gap with Eggs (Embargo May 2, 2007)
Researchers at Iowa State University assessed choline intake in the diets of specific subsets of the U.S. population and found that usual intake is far below the Adequate Intake (AI) levels for older children, men, women and pregnant women. Only 10 percent or less of these populations are eating close to the recommended amounts of choline. This study , which is one of the first to assess choline intake in the population , is important because choline is an essential nutrient needed for normal functioning of all cells and for brain function. The finding that choline intake is low among pregnant women is particularly noteworthy as previous research has demonstrated that choline may help with brain and memory development in fetuses. 4 , 5 The National Academy of Sciences recommends increased choline for pregnant and breastfeeding women (550 mg and 450 mg, respectively). Additionally, a separate study presented at this week's National Nutrient Data Bank Conference found that choline intake decreases with age and that adults ages 71 and older consume an average of about 264 milligrams per day , roughly half of the AI for choline (550 mg/day for men, 425 mg/day for women). Both studies recommend increased consumption of foods that are good sources of choline to help close the gap on choline consumption. Eggs are an excellent source of choline. Two eggs contain about 250 milligrams of choline, or roughly half the recommended daily supply. (Other rich sources of choline include beef liver and wheat germ.)
Putting Egg Recommendations Into Perspective (Embargo April 30, 2007)
Researchers are beginning to challenge egg consumption restrictions that are based on studies that examined dietary cholesterol and saturated fat together. Research on the independent effect of dietary cholesterol shows no significant effect on heart disease risk. A relative risk study conducted by the Washington, DC-based scientific consulting firm Exponent concluded that eggs' contribution to coronary heart disease risk is insignificant. 7 The study evaluated the relative risk of heart disease associated with egg consumption compared to other risk factors, including age, genetics, dietary pattern, smoking, alcohol consumption, high blood pressure, serum cholesterol, obesity, diabetes and sedentary lifestyle. After a thorough scientific review of the major studies concerning heart disease causation, it was found that eggs contribute just 0.6 percent of males' and 0.4 percent of females' coronary heart disease risk, when other modifiable risk factors are assumed. Research like this may help change wide-sweeping recommendations to restrict egg consumption to avoid heart disease, particularly when the positive nutrition contributions from eggs are considered. Eggs contain a number of nutrients in varying amounts , including the highest-quality protein, choline, folate, iron and zinc , for only about 75 calories. Eggs also contain small amounts of lutein and zeaxanthin, which may be involved in the prevention of cataracts and age-related macular degeneration.
edelman