Fats.. Good or Bad?

FAT – GOOD OR BAD?

It is pretty difficult to pick up a paper or see the news today without seeing an item related to fat. Some kinds are good, some kinds are bad, how much is too much, how much you need, how much is in different foods, both at home and in restaurants. How can anyone make sense of all this information? Let’s start at the beginning and see if we can figure out some of the basics. There is definitely more than one column here!

Fats of all sorts are key components of our diets, and are necessary for a balanced diet. Fats are a way of storing energy, and it has been said that the love of fat that we humans seem to show originated thousands of years ago, before there were Superstores.

Fat is stored in the bodies of mammals as a way of storing energy for future needs. It is “burned” in the same way as we burn a candle, although there is no flame in a body, to produce heat. This heat keeps the organism alive and the carbon dioxide that is produced in the process is exhaled in respiration. Fat also serves as a very good insulator. Large marine mammals can live comfortably in freezing water due to their thick layer of fat and still preserve a warm inner body temperature.

Fats occur naturally and chemically they have several features in common. They belong to a family of compounds called triglycerides that you may have heard of. Think of a triglyceride as a tiny capital E, with the three branches made up of a chain of carbon atoms of varying length. If all three branches are 16 carbon atoms long, you have palmitic acid, found in olive oil. It is called an acid because of the carbon and oxygen atoms on the end of the chains, not because it dissolves metal. Changing the length of the carbon branches to 12 carbons gives lauric acid, found in coconuts. So the length of the carbon chain, and whether all three branches are the same gives the fats their unique properties. Natural fats and oils are almost always mixtures of several fats.

Now it gets a bit complicated, so please bear with me. If we think of these branches as a chain, palmitic acid would have 15 links, with one extra carbon for the acid group. Some fats however, have a double bond in the chain… think of it as two links of the chain side by side, with the overall length unchanged. This double link means that the physical properties of the fat are changed, and generally more double bonds mean liquid oils, and fewer means solids such as lard and butter. Years ago, chemists discovered that they could add hydrogen to these unsaturated fats, and turn liquid oils into solids that were easier to store and did not spoil. So this is where the terms saturated, or hydrogenated, and unsaturated fats originated.

In a fat such as butter, these branches are very short. This means that butter melts at a very modest temperature, about 30 deg. C. It also means that butter can easily be scorched and the molecule broken down at higher temperatures, which is why you would not use butter to make French fries.

Let’s take a look at a recent trend … omega-3 fatty acids. In chemistry we use various Greek letters to tell us where those double bonds that I mentioned above are located. As you would expect, omega-3 fatty acids have their double bond in a very specific location on the carbon chain, third from the end, and this gives them unique properties. First, there are two common ones, known mercifully by their initials as DHA and EPA. There is another common one known as ALA, which we will come back to. DHA and EPA are found in fatty fish such as salmon, tuna, mackerel, and sardines. These fats have been linked, and I use that term reservedly, to benefits such as a lower risk of heart disease, cancer, Alzheimer’s, and several other health problems. So food manufacturers, quick to spot a trend, are claiming that their food contains omega-3 fatty acids, or they have added omega-3 to their product. However, make sure you read the fine print, because ALA which I mentioned above has almost no demonstrated benefits, but is cheap to produce and add to foods. If the label doesn’t clearly mention DHA and EPA, it is likely the ALA acid, and the claim, while technically correct, likely results in minimal or no benefit. As well, check to see how much is in your food. With some foods you would need to consume enormous quantities to get the same amount of omega-3 that could be obtained in one portion of salmon, for example.

So what is a consumer to do? My colleagues in the nutrition field will probably recommend a balanced diet, with minimal fats and sugar, and several portions of fish, and lots of fruit and vegetables, along with adequate exercise. That approach will give you the best health benefit. That is my objective, and along with carefully reading the label and taking advertising claims with some scepticism, I hope to enjoy a long life.