You probably already know that fish oil is good for us and that trans fats are bad, but do you know why? Do you know about omega-6 fats? Knowing how things work makes it easier to choose healthy foods. The role of fats is pretty interesting anyway.

First, we really do need fats. Every cell in your body has a membrane made of fat. In nature, oil and water don't mix, and that is why having fats in your cell membranes is so important. They provide a natural protective barrier between the outside of the cell and the inside. These membranes are seven millionths of a millimeter thick - so thin that they can only be seen with an electron microscope. We didn't even know about them until the 1950's.

Okay - so we have these ultra-thin membranes made of fat. They are heavily influenced by the type of fat you eat! Saturated fats like butter, lard, shortening and the fats marbled in meat are all solid at room temperature. Unsaturated fats like olive oil are liquid at room temperature. This is what happens in our body, too. Saturated fats give us rigid cell membranes, while unsaturated fats give us flexible cell membranes; a definite advantage for a cell membrane.

This has to do with the physical structure of the fats. Saturated fats have a straight shape and can be packed into the cell membrane more solidly. That does not give much room for messenger proteins to get important things like nutrients and enzymes into the cells. The two most active forms of omega-3 fats, EPA (eicosapentanoic acid) and DHA (docosahexaenoic acid), have a long structure and multiple double bonds. The double bonds give them a small bend. They can't be packed as tightly as straight fats, so they create extra space in the cell membrane, giving it flexibility and fluidity.

Imagine packing flexible straws into a box - you can pack straight straws tightly into the box, but once they are bent you can't get as many in. The reason that trans fats are so bad is that the chemical process to hydrogenate them changes their shape to a sharp right angle which actually damages the cell. Imagine trying to fit straws with an L-shaped bend into the box, it doesn't work! Interestingly, there are a few natural trans fats found in nature, but their shape is less rigid and less damaging than artificially produced trans fats. Keep in mind that any food listing hydrogenated or partially hydrogenated fats has some trans fats, even if the label claims zero trans fats. This is because of a quirk in labeling laws.

Like us, animals are made of the kinds of fats that they eat. Fish need flexible membranes because they have to survive in cold water. They need a type of fat that stays fluid and allows them to move easily in cold conditions, which makes fish the best source of EPA and DHA for us. They are more efficient than mammals at synthesizing it from a more elemental form of omega-3 (ALA or alpha-linolenic acid). Animals that are fed greens (grass fed beef, free range chickens, lambs) have more omega-3 fats in their bodies than animals fed grains, but not as much as fish.

Omega-6 fats are another form of fats that show up in cell membranes. These are related to omega-3 fats but don't have the same level of elasticity. There is another important difference between the two: omega-3 fats reduce inflammation and omega-6 fats increase inflammation. Think of omega-6 fats like the heavy guns. If you have a health related emergency, having them could save your life as they clot damaged blood vessels and preserve life sustaining blood. But in peaceful times they can be too much, promoting clotting where it isn't needed and putting you at risk.

While we need some omega-6 fats in our diet, the Standard American Diet (SAD) contains too much of them. Our original diet provided a 2:1 ratio of omega-6 to omega-3 fats. The current American way of eating gives us a ratio closer to 15:1. While not all scientists agree, many think that this makes us more susceptible to inflammatory diseases like heart disease, diabetes, obesity, dementia and cancers.

Where do all these omega-6 fats come from? They are found in vegetable oils, processed and fried foods, and grain fed animal products. Vegetable oils contain both fats, but most have more omega-6's than omega-3's. Corn oil is especially high in omega-6, but sunflower and safflower rank up there too. Soy oil is more balanced, although it is frequently modified to make it more solid (and soy is one of the primary genetically modified crops). Canola oil has a good balance of omega-3 fats, but it too is often genetically modified. Olive oil is the best choice for low temperature cooking.

Omega-3 fats are impossible to use in processed foods. They don't have a shelf life: because of their chemical structure, they break down quickly. This gives me a whole new perspective on fresh foods. We buy shelf life at a cost! Processed foods are convenient but are made with unhealthy fats. While there are always exceptions, in general it is wise to choose more fresh foods and less processed ones.

A final thought about the primary omega-3 fats, EPA and DHA. EPA is critical for heart health and DHA is very important for brain functions. DPA impacts intelligence, the ability to learn and mental health. One of the reasons that breast milk is so good is that it is a great source of DHA! Because a significant amount of the mother's DHA goes into breast milk, if she doesn't replace it in her diet she is at higher risk for post-partum depression and may have less available for a second child.

The bottom line:
• Eat more fresh foods and less processed foods.
• Use olive oil as your primary oil. If you eat animal protein, buy products from animals fed greens instead of grains.
• Get EPA and DHA regularly from oily fish and/or fish oil. If you are pregnant supplement with DHA.
• If you use an infant formula, find one with DHA or speak with your physician about adding it yourself.