In the last blog we discussed saturated fats.  We will continue to discuss fatty acids with monounsaturated fats.

II. Monounsaturated Fat

Monounsaturated fatty acids are liquids at room temperature and semisolid or solid when refrigerated.  Foods containing monounsaturated fats reduce low-density lipoprotein (LDL, the “bad”) cholesterol, while possibly increasing high-density lipoprotein (HDL, the “good”) cholesterol.

There are two types of monounsaturated fatty acids.

1. Palmioleic acid (Omega 7) is found mainly in dairy foods.

The good: Recent evidence shows that palmioleic acid reduces the incidence of heart disease since it decreases blood cholesterol.  It also lowers blood glucose levels thereby reducing the risk of type II diabetes.  Milk is also a good source of protein.

The bad: I read over and over “Only calves should drink cow’s milk.”  The negative aspects of dairy consumption are starting to out-number the positive.  Dairy products contain a lot of saturated fat if you don’t choose “fat-free” products.  Allergies and lactose intolerance are increasingly more common.  Because of consumer awareness more people are avoiding mass produced milk and selecting hormone and pesticide-free dairy products. It is proven that sebaceous glands secrete more oil after consumption of all (even fat-free) dairy products.  The response to dairy products mimics the reaction that occurs during puberty when we have increased oil production, which leads to acne.

2. Oleic acid (Omega 9) is what we commonly think of when referring to a monounsaturated fatty acid since olive oil (an omega 9) is becoming more commonly used in American food.

Various foods contain oleic acid.  The richest and most common source of oleic acid is the olive and olive oil. Avocados, canola oil, nuts and seeds all contain oleic acid in varying amounts.

The good: The beneficial health effects of olive oil are due to both its high content of monounsaturated fatty acids and its high content of antioxidative substances.  Studies have shown that olive oil offers protection against heart disease by controlling LDL cholesterol levels while raising HDL levels. Olive oil is the cornerstone of the Mediterranean diet.

The bad: There is nothing really bad about fresh olive oil.  However, olive oil can oxidize easily. Olive oil, as any other product containing antioxidants and/or oil is vulnerable to oxidation when it is exposed to light and oxygen.  It must always be stored in an airtight, dark bottle and kept in a cool environment.  Oxidized oils are dangerous to your health because they oxidize the cholesterol in your body and can also deplete our body’s antioxidant supply.  Oxidation destroys antioxidants.

The inception and evolution of trans fats

In the early part of the 20^th century we started to import soybeans because they were an inexpensive source of protein.  The protein was extracted from the soybean leaving a huge surplus of soybean oil.  Soybean oil gets rancid very quickly so the food industry found a way to stabilize the liquid oil. They chemically altered unsaturated fat by hydrogenating (adding hydrogen to) the oil creating trans fats.

Everyone thought this was a great idea since:

1) We were consuming “unsaturated” fat instead of butter and lard.

2) It was very economical since it can be produced in a lab avoiding all of the time, effort, and money spent on obtaining it from animals.

3) Convenience was an issue also since margarine, made with hydrogenated soybean oil, could be spread on food as soon as it was removed from the refrigerator because it remained soft even while cold. The new fat (e.g. Crisco) became liquid when heated, which made it even better than lard for frying food.

4) The stability of this new oil solved the problem of oils becoming rancid. Inexpensive, stabile oil allowed the food companies to develop a variety of  economical packaged foods.  A lot of hydrogenated vegetable oils are used in packaged foods.

The production and consumption of trans fats steadily rose through the 20^th century.  In 1994, it was estimated that trans fats caused 20,000 deaths annually in the US from heart disease. What started as a “healthy, unsaturated fat alternative” turned out to be much worse than the saturated fat products we were trying to avoid.

In 2002 the National Academy of Science (NAS) stated that:

1)      “dietary trans fatty acids are more deleterious with respect to coronary heart disease than saturated fatty acids”

2)      “trans fatty acids are not essential and provide no known benefit to human health” whether of animal or plant origin.

The NAS goes on to say that while both saturated and trans fat increase the levels of LDL (bad) cholesterol, trans fat also lowers levels of HDL (good) cholesterol, thus increasing the risk of coronary artery disease.

Identifying trans fats on product labels should be pretty easy since the U.S. government, in January 2006, required food manufacturers to list them on the Nutrition Facts panel. Consumers now know how much of all three—saturated fat, trans fat, and cholesterol—are in the foods they choose.

Since food manufacturers had to adhere to the law, they removed most of the trans fat from their products.

Interestingly, trans fats have not disappeared from packaged foods in 2011. A label from a recently purchased box of Saltine Crackers states it has 0 trans fat. However, in the ingredient list there is “partially hydrogenated cottonseed oil,” which is bad fat. Cottonseed oil is inexpensive and naturally high in saturated fats. In this case, it is hydrogenated to further extend its shelf life.

It’s difficult but not impossible to avoid trans fats.  Since we cannot avoid every single gram of bad oil, we can consume omega-3 oil to help reverse the negative effects of bad fats.