|
 Trans fats, on the other hand, were associated with an increased
risk of death from any cause, death from cardiovascular disease and
a diagnosis of coronary heart disease.
Dietary guidelines recommend that saturated fats, found in animal
products like butter, egg yolks and salmon, make up no more than 10
percent of daily calories. Trans unsaturated fats, known as trans
fats, like the hydrogenated oils that keep processed foods and
margarine shelf-stable, are primarily industrially produced and
should provide no more than one percent of daily calories.
For the new review, researchers at several Canadian institutions
including McMaster University in Hamilton, Ontario, included data
from 41 studies of the association between saturated fat intake and
health outcomes, covering more than 300,000 people, and 20 studies
of trans fat intake and health outcomes that covered more than
200,000.
Saturated fat intake was not tied to coronary heart disease,
cardiovascular disease, stroke or type 2 diabetes, but its link to
risk of death from coronary heart disease was unclear.
Consuming industrial trans fats was associated with a 34 percent
increase in all-cause mortality, a 28 percent increased risk of
heart disease mortality and a 21 percent increase in the risk of
heart disease, the study team reports in The BMJ.
Because the evidence was uncertain for saturated fats, more studies
would be helpful, the researchers write. None of the studies they
included were randomized controlled trials, the most rigorous type
of study; all were based on observation over time, so other factors
in participants’ lives could have played a role in their health
outcomes.
Several reports since 2010 have confirmed that saturated fats are
not associated with heart attack or stroke, said Dr. Ronald M.
Krauss of Children’s Hospital Oakland Research Institute in
California, a coronary artery disease expert who was not part of the
new review.
Saturated fats are found in dairy, red meat and tropical oils, he
said. “Among these, the only category consistently associated with
heart disease risk is red meat, and even in this case, it's not
clear that saturated fat all by itself is the main culprit,” Krauss
told Reuters Health by email. “There may be other potential
mechanisms.”
Unlike saturated fats, trans fats lower "good cholesterol,” he said.
Among men, trans fatty acid intake declined between 1980 and 2009
from 2.9 percent of daily calories to 1.9 percent, according to a
2014 study (see Reuters Health story of October 22, 2014 here:
http://reut.rs/1z0fHu4).
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“We have known that trans fats are bad for us, and the evidence for
that has been strong enough that these fats are now being removed
from the food supply,” said Patty W. Siri-Tarino, also of Children's
Hospital Oakland Research Institute.
The U.S. Food and Drug Administration has given food manufacturers
until 2018 to remove trans fats from the food supply, she told
Reuters Health by email.
There is now enough evidence to shift focus from the amount of
saturated fat in the diet to intake of specific food categories,
Krauss said.
Individual saturated fats vary widely in their food sources as well
as their potential health effect, said Dr. Rajiv Chowdhury, senior
cardiovascular scientist at the University of Cambridge in the U.K.
Some are harmful while others may actually be beneficial, so their
total amount in the diet seems to have no association with health
outcomes like death, he told Reuters Health by email.
More research on saturated fats is needed, and trans fats should be
totally avoided in the diet, Chowdhury said.
“This study shows that focusing on reducing saturated fats as the
primary goal in eating well is not quite right,” Siri-Tarino said.
“Eating well means replacing those saturated fats with
polyunsaturated fats rather than carbohydrates, particularly refined
and processed carbohydrates, which is what usually happens,” she
added.
“There are still people who will benefit from controlling the amount
of saturated fat they consume, but it's not the most important part
of the diet to be concerned about,” she said.
SOURCE: http://bit.ly/1sk4kGq The BMJ, online August 11, 2015.
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