Polyunsaturated fats include omega 3 found in certain vegetable oils and omega 6, found in fish and green leafy vegetables.
The authors base their findings on 132 patients with potential or definite amyotrophic lateral sclerosis (ALS), one of the disabling conditions known as motor neurone disease.
Motor neurone disease is thought to be caused by genetic and environmental factors, and diet has been previously implicated in its development.
The patients completed a questionnaire, detailing their regular dietary intake before they became ill of polyunsaturated fats (PUFAs), vitamin E, and a range of other nutrients, among them flavonols, calcium, and lycopene.
The results were compared with those of 220 healthy people and adjusted to take account of other factors likely to influence the findings, including age, sex, energy intake, weight, and smoking habit.
Total energy intake and consumption of dietary supplements were the same in both groups, but intake of total fats differed. The patients with ALS consumed significantly less PUFA and vitamin E than their healthy peers.
The highest daily intake of PUFA of more than 32 g was associated with a 60% lower risk of developing ALS compared with the lowest daily intake of less than 25 g.
Similarly, a daily vitamin E intake of between 18 and 22 mg was associated with a 60% lower risk of developing ALS compared with the lowest daily intake of less than 18 mg.
PUFA and vitamin E seemed to work synergistically, the researchers found, and the results held true even after taking account of other influential factors. No strong associations were found for any of the other nutrients.
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He illustrated how effective the the program could be by saying an 8-year-old who cuts 45 calories a day from his diet would be 20 pounds (9 kg) lighter by the time he or she graduates from high school.
Clinton has lauded the beverage industry for taking a risk with the initiative, but one expert has said vending machines in schools are not a major source of revenue for carbonated soft-drink manufacturers and the effect will be minimal.
The move is expected to affect 87% of the school drinks market but many believe soft drinks are a visible and easy target and other factors are equally responsible for childhood obesity.
The beverage industry has agreed to apply the new limits to 75 percent of the nation's public and private schools before the start of the 2008-09 school year and apply it to all schools a year later.
In future elementary schools will sell only water, small servings of juices with no added sweeteners, and small servings of milk that are fat-free or low-fat.
Middle schools will have the same restrictions while allowing slightly larger portion sizes.
For high schools, at least half of available beverages must be water, zero-calorie and low-calorie drinks.