吃酪乳(cheese)不會增加血中LDL

我一直在懷疑吃很多cheese (乳酪) 會不會促使血管硬化加快。不過記得地中海區很多活到很老的人說，他們長壽的秘訣就是吃cheese。

現在丹麥的研究報導 cheese (乳酪)
和 butter (牛油)
不一樣。吃cheese 後不會像吃 butter，不會使血中對血管硬化有害的 low density lipoprotein (LDL) 增加。其原因不明，可能和 cheese 中含有鈣質(會促使脂肪從消化道排泄)、含有發酵的蛋白質有關。

(Reuters)
- Doctors and nutritionists have long recommended avoiding all animal fats to
trim cholesterol, but Danish
researchers say cheese may not be so bad, and probably
shouldn't be placed in the same category as butter.

According
to their study, published in the American Journal of Clinical Nutrition,
people who ate daily servings of cheese for six-week intervals had lower
LDL cholesterol, the so-called "bad"
cholesterol, than when they ate a comparable amount of butter.

The cheese eaters also did not have
higher LDL during the experiment than when they ate a normal diet.

"Cheese
lowers LDL cholesterol when compared with butter intake of equal fat content
and does not increase LDL cholesterol compared with a habitual diet,"
wrote Julie Hjerpsted and her colleagues,
from the University of Copenhagen.

The group surveyed about 50 people. Each
person was put on a controlled diet and added a measured amount of cheese or
butter daily.

Throughout, each participant was compared
against his or herself, to follow changes in the body caused by the foods.
Researchers gave each person cheese or butter, both made from cows milk, equal
to 13 percent of their daily energy consumption from fat.

During
six-week intervals, each person ate the set amount of cheese or butter,
separated by a 14-day cleansing period which they returned to their normal
diet. Then they switched, and for six weeks those who had eaten the cheese
before, ate butter, while the butter eaters in the first phase ate cheese.

Despite eating more fat than had been
in their normal diet, the cheese eaters showed no increase in LDL or total
cholesterol. While eating
butter, however, the same subjects had LDL levels about seven percent higher on
average.

While eating cheese, subjects' HDL or
"good" cholesterol dropped slightly compared with when they ate
butter, but not compared with their normal eating period.

The researchers speculated that there
could be several reasons why cheese affected people differently than butter.
But there is nothing conclusive in the study, which was supported by the Danish
Dairy Board and the National Dairy Research Institute.

For
one, cheese has a lot of calcium, which has been shown to increase the
amount of fat excreted by the digestive tract. Researchers did detect a
little more fecal fat during the time the group ate cheese, but the amounts
were not statistically significant.

Other
possible explanations involve the large amount of protein in cheese and
its fermentation process, both of which could affect the way it's digested
compared to butter.

Elizabeth
Jackson, assistant professor of medicine at the University of Michigan Health
Systems, told Reuters Health that the study was well done but does not really
change what cardiologists currently recommend.

"We
want people to have a diet focused on whole grains and vegetables and moderate
fats," said Jackson, who was not involved in the study.

"In
terms of cheese, anything in moderation," she added.

(Reporting
from New York by Andrew Seaman at Reuters Health; Editing by Elaine Lies and
Yoko Nishikawa)