|
The first four fatty acids are saturated
fatty acids. Notice that the first three (Lauric, Myristic, and
Palmitic) have a negative impact on blood cholesterol levels (increasing
LDL levels), but they ALSO have a positive impact as well (increasing
HDL levels). Saturated fats get a bad reputation for being
unhealthy, but recently there has been more information stating that the
link between saturated fat and heart disease may not be as strong as we
once thought.
In an article from Tufts University
Health & Nutrition Letter (May 2010), Links Between Saturated Fat,
Blood Cholesterol & Heart Disease Prove Complex, a researcher
from Children's Hospital Oakland Research Institute, Ronald M. Krauss,
MD stated that, "Our meta-analysis showed that there is insufficient
evidence from prospective epidemiological studies to conclude that
dietary saturated fat is associated with an increased risk of
cardiovascular disease (CVD)."
Researchers state that one reason
reducing saturated fat intake may not decrease CVD risk is because
people tend to replace saturated fat with processed carbohydrates.
You can read more about this in, "Is
eating fat really bad for you? Here is what the science says."
"An overall eating pattern that
emphasizes whole grains rather than refined carbs such as white flour,
along with foods high in polyunsaturated fats, such as fish, seeds, nuts
and vegetable oils, is of more value for reducing coronary heart disease
risk than simply aiming to further reduce saturated fat," states Krauss.
Coconut oil has been getting lots of
media attention lately, claiming that the saturated fat in coconut oil
does not have a negative impact on heart health. Many of these
articles are often sensationalized, even articles from credible sources
like the following: "Coconut
Oil". Keep in mind research on coconut oil is pretty new and
while it may have some potential, there are still some concerns about
how it may impact heart health and cholesterol levels. Often people
forget that coconut "oil" is a very processed/refined food and should be
limited like other processed/refined foods.
Overall, I still agree the message really
needs to be to displace
saturated fat with unsaturated fat, and to eat a balanced diet with a
variety of whole foods.
Trans Fatty
Acids
Trans Fatty Acids
are a bi-product of hydrogenation. Hydrogenation of polyunsaturated fatty acids saturates
the fatty acid with hydrogen
(creating saturated fatty acids), but it does leave some of the double bonds
as well, creating trans fatty acids. As you can see from the image
below trans fatty acids are actually a monounsaturated fatty acid, but
they have the shape of a saturated fatty acid (they are not kinked like
the naturally occurring monos in olive oil due to the configuration of the hydrogens at the double bond). These partially hydrogenated and
artificial fatty acids (trans fatty acids) now have an unusual shape
that act similar to saturated fatty acids in the body.
In about the 1990s, evidence began accumulating that
trans fat are not healthy, “Numerous studies have found that trans
fats raise our risk of heart disease," says Cynthia Payne, a registered
dietitian at the University of Maryland Medical Center. "They can also
contribute to an increase in LDL levels and a drop in the
healthy HDL cholesterol. These man-made fats are much worse for you
than any other natural fat, even the saturated fats found in butter and
beef.”
Substitutes for trans fats- In 2006, the U.S. government
began requiring trans fat information on the Nutrition Facts of food
labels. This has prompted the food industry to mostly eliminate the use of
partially hydrogenated fat.
What they are
sometimes using instead are the same palm oil and coconut oil (both of
which contain saturated fat) that they removed from their products in the
1980s. Below you can see that this margarine has 2.5g of saturated fat
which is primarily coming from palm oil.
 
Food Labels and Trans Fat:
As you might suspect labels
can be tricky when it comes to trans fat. A product can say
Zero Trans Fat, and that does not necessarily mean the product is
heart healthy as it may still be high in saturated fat, like the
below label.
Also, if a product has 0.5g or less
of trans fat the label can state 0g of trans fat. Therefore, you have to
look at the ingredient list to really know if a product contains trans
fat. You want to look for partially hydrogenated oils in the
ingredient list to determine if there is trans fat present.
|
| |
More About Hydrogenated Fats:
In an attempt to find an inexpensive substitute for butter, as far back
as 1903, Britain was adding hydrogen gas to liquid (polyunsaturated)
oils in a process called hydrogenation. This hydrogen reacted with the
double bonds in the structure of the unsaturated fatty acids of the
corn oil. Hydrogenation creates both saturated and trans fatty
acids. The purpose was to make the oil
solid at room temperature (so margarine and shortening were possible from oils like corn oil), it also
increased shelf life by making the oil more stable and less likely to go rancid
(so baked goods like cookies and chips could sit on the shelf longer).
When
concerns arose in about the 1970s and 1980s about the saturated fats in
the palm and coconut oils used in baked goods and margarine (in part
because they were cheaper than butter) they were often replaced with
these hydrogenated fats made from oils from corn and soybeans. When
used in cookies or potato chips, instead of using an oil like corn oil that
contains polyunsaturated fats, the product had a longer shelf life.
And products like margarine made with hydrogenated corn oil were solid similar to
butter. McDonald's and Kentucky Fried Chicken found the hydrogenated
fats gave a wonderful crispness to their French fries and chicken that
was difficult to replace. Jif liked the smooth “mouth feel” small
amounts of it added to their peanut butter.
Since margarine companies want to advertise their product as
having no trans fat, they have been using other ways of making their
margarine solid and spreadable. What some companies are choosing
to use are things like palm "oil", or fully hydrogenated oils which is high in saturated fat.
|
