Eating the Right Fats for Health, Part Two

[This article series originally appeared in Equilibrium.]

Part Two: The Unhealthy Fats

In the first installment in this series, I provided a brief introduction to the various lipids (fats) we consume in our diet. Although I didn't go into depth about any one lipid and its risks or benefits, I hinted at some of this information. This time we will learn which fats are dangerous and why, and how to avoid or mitigate their potential threat to our health.

First, the bad news: excess dietary fat has been linked to heart disease, obesity, autoimmune disorders, colon cancer, prostate cancer, breast cancer, and inflammatory diseases such as arthritis. In terms of caloric intake, one gram of fat yields nine calories, while protein and carbohydrates each yield four calories. It has long been assumed that eating fat can make us fat -- in fact, eating the wrong fats can kill us.

Now, the good news: not all fats are equal. A handful of researchers, most notably the late Dr. Atkins, were able to prove that dietary fat is not the only factor that makes a person overweight. Their research and dietary strategies showed that carbohydrates -- and the associated rise in insulin levels -- are the most significant cause of body fat accumulation. These researchers also discovered that certain fats, such as the omega-3s, are good for us.

Saturated Fat

For years we have known that saturated fat increases serum cholesterol and is a leading cause of atherosclerosis (fat deposits in arteries). We know, therefore, that high-fat animal foods seriously increase the risk of heart disease and stroke. Unfortunately, this knowledge hasn't led to healthier dietary habits for the majority of Americans.

We also know that saturated fat is preferentially stored in adipose tissue (the body's fat cells), which explains why eating fat makes us fat. Because saturated fats have no double-bonded carbons in their structure, they can yield more energy per carbon than if they had double bonds (like the omega fatty acids), which is why the body stores them in adipose tissue.

The human body uses fats according to their structure. Polyunsaturated fats are used as the building materials for cell membranes due to their flexibility. Saturated fats are much more rigid, so the body will use them only as stored energy. Consuming saturated fats with a high carbohydrate meal (which significantly raises insulin) will result in the saturated fat quickly being shuttled into adipose tissue. A Big Mac, fries, and a milk shake are the perfect recipe for fat storage.

However, while the fat is still circulating in the blood, it has a tendency to clump due to its long-chain structure. These clumps of fat can be deposited within arteries, organs, and even muscle. When these clumps of fat are deposited in organs or around glands, they greatly increase the risk of cancer.

One possible explanation for the increase in cancer risk due to fat accumulation is the estrogenic properties of fat tissue. While estrogen is necessary for normal health, excess estrogen has been linked to breast and prostate cancers, and is suspected in several other forms of cancer, including colon and skin cancers. It turns out that adipose tissue not only has more estrogen receptors than normal cells, but it also can create estrogen. Therefore, the more adipose tissue a person carries, the higher the risk of developing certain types of cancer.

For many years, we thought saturated fat was the worst fat in the diet. But there has been a lot of research in recent years showing trans-fatty acids to be equally, if not more harmful.

Trans-Fatty Acids

Trans-fatty acids (TFAs) are created by the hydrogenation of mono- or polyunsaturated lipids. The process involves adding hydrogen to a vegetable oil in a complex chemical reaction involving high heat and pressure. The resultant oil is solid at room temperature and becomes rancid much more slowly. TFAs are used in most processed foods and are the foundation of margarine and vegetable shortenings.

Natural unsaturated oils are in a "cis" format, meaning that the hydrogen atoms are all on the same side. This allows the lipid to be more flexible, and most polyunsaturated fats are, in fact, curved, allowing them fit within cells without abnormally altering the cell's shape.

During the hydrogenation process, the hydrogen atoms move to the opposite side of the carbons, thus the designation "trans." This creates a fat molecule that is even more rigid than saturated fat -- a molecule produced naturally only in the stomachs of ruminate animals. When TFA molecules, which resemble saturated fat more than unsaturated fat, are used in the formation of new cells and cellular membranes, they create more rigid -- and unhealthy -- cell structures.

Research has also shown that TFAs increase cholesterol at least as much as do saturated fats, possibly more. Although both types of fat seem to increase LDL cholesterol (the bad kind) equally, TFAs also reduce HDL cholesterol (the good kind). This factor alone makes them more harmful than saturated fats.

But trans-fats are also implicated in increasing lipoprotein levels, which results in the formation of arterial plaque. The combined action of lowered HDL, increased LDL, increased cholesterol, and increased lipoproteins makes TFAs the single greatest dietary risk for coronary heart disease. In addition, TFAs contribute to the risk of type II diabetes and have been linked to the onset of several forms of cancer.

TFAs have absolutely no health benefits. All foods containing these fats are now required to list them in the nutrition panel. They should be required to carry a clear warning label, just like a pack of cigarettes. Personally, I believe that TFAs are as deadly as cigarettes. In fact, Holland has banned TFAs from food production, a step we unfortunately are not likely to see here.

Omega-6 Fats

As I will discuss next time, omega-6 fatty acids are crucial to our health. Linoleic acid, the primary omega-6 lipid, is an essential fatty acid, meaning we must consume it in our diet because the body cannot produce this lipid on its own. However, our dietary intake of omega-6 fatty acids is so out of balance with our intake of omega-3 fatty acids that omega-6 fats can be considered a health risk.

Until the industrialization of food production began about 100 years ago, the human diet was essentially balanced in its omega-3 and omega-6 intake. The optimal balance is 1:1, with 1:3, omega-3 to omega-6, being acceptable. The average American diet is in the range of 1:25 to 1:35.

This imbalance creates a variety of health risks, especially for inflammatory diseases like arthritis. One of the omega-6 fats, arachidonic acid (AA), which is found in animal fats and is also produced by the body, is essential to our health but can become toxic when not balanced by adequate omega-3 intake.

Our bodies and brains are adept at regulating the amount of AA formed from dietary lipid intake. However, when we also consume a lot of animal fat, we not only get unhealthy saturated fat, we get much higher levels of AA than the body needs. The higher levels of AA, if not offset by adequate levels of omega-3 fats (especially EPA, which is found in fish oil), produce a variety of highly reactive substances.

Among the substances produced by high AA intake are prostaglandin E2 (associated with inflammation, pain, and swelling), leukotrienes (which cause pain and swelling, and are 1,000 to 10,000 times more inflammatory than histamine), and thromboxane A2 (which can cause increased blood clotting and blood vessel spasm). These substances produced by AA are the reason why arthritis patients are warned to avoid red meat (which has higher fat content than other forms of meat).

What We Can Do

The following suggestions can limit the negative impact of unhealthy fats.

* Completely avoid trans-fatty acids if possible, or, at the very least, severely restrict your intake of them.

* Limit saturated fat to less than 10 percent of total fat consumption.

* Try to keep dietary fat to less than 30 percent of total calories unless following a low-carbohydrate diet. Although lower fat diets are often healthy, falling below 20 percent of total calories from fat can be harmful for many people.

* When choosing meat and dairy products, try to find free-range or grass-fed products. For example, free-range chicken and eggs are roughly 1:2 omega-3 to omega-6 fatty acids, whereas grain-fed products are between 1:20 (chicken) and 1:40 (egg yolks).

*Increase intake of omega-3 fatty acids in the form of flax seed or oil, walnuts, pumpkin seeds, hemp seed or oil, and fish oils to balance omega-3 to omega-6 intake.

* Eat cold-water fish and/or use fish oil capsules, which is especially important in reducing cellular levels of arachidonic acid.

In the last installment, I will discuss the good fats, their benefits, and how to include them in our diets.