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Nutrient Series: Fats
Everyone talks so negatively about dietary fat these days, especially regarding weight control and disease. But these little molecules do so much for our bodies! Yes, fat is good for you and helps with the metabolism of carbohydrates and proteins.

When we talk about fats in the diet, we’re actually talking about lipids. Lipid is the umbrella term for oils and fats, both necessary in our bodies. Oils are liquid lipids and fats are solid lipids. Technically our diet consists of protein, carbohydrate and lipid.

It’s important to know what a lipid is. Lipids are made up of glycerol, a molecule that looks like an “E” and is the backbone of all lipid structures. Different molecules called fatty acids attach to the arms of the glycerol molecule. Most lipid molecules contain three fatty acids, are called triglycerides and make up 99 percent of the fat stored in the body. Triglycerides provide energy, insulation, protection of organs and metabolic functions.

Triglyceride molecules often form chains and have bonds linking them together. Fatty acids contain hydrogen atoms, but if some of the fatty acid molecules on the chain don’t contain a hydrogen molecule, it’s referred to as an unsaturated fatty acid. Unfortunately, when an unsaturated molecule is exposed to oxygen, it can become rancid. So manufacturers began adding hydrogen to foods to make them more stable for storage, and now often include antioxidants, like BHA and BHT, to protect the product.

Adding hydrogen, called hydrogenation, also changes the physical property of a food, making liquid oil more solid. Without hydrogenation, you couldn’t spread margarine on your morning toast! On the other end, butter is already solid, so hydrogenation is not required.

Unfortunately, we have recently found that hydrogenating foods also makes something called a trans fatty acid, which is not healthy. The recent fad of dipping bread into unsaturated olive oil is a healthier alternative to processed margarines for this reason, and probably accounts for better heart health in Italy. Unsaturated molecules are more fragile and therefore easier to metabolize. Saturated fats, on the other hand, are more difficult to break down. Naturally saturated fats don’t contain trans fats.

The most commonly known fatty acids are the Omega fatty acids. Your body can make all but two fatty acids, Omega 3 and Omega 6. These are known as essential fatty acids and must be available in the diet for your body to function. Linoleic acid is the chief Omega-6 fatty acid and is found in meats, nuts and seeds, grains, leafy vegetables and vegetable oils. From linoleic acid, the body can make all other necessary Omega-6 fatty acids.

The other essential fatty acid, Omega-3, is found in fats and oils, soybeans, nuts and seeds, and many types of fish and shellfish. The primary Omega-3 is linolenic acid.

Parents of infants are probably familiar with ARA and DHA, fatty acids recently added to commercial formulas for brain growth and vision. One of the most abundant sources of DHA is human breast milk. Both ARA and DHA can be made by the baby from the linoleic and linolenic acids already added to formula years ago, making these recent additions unnecessary.

There are two other kinds of lipids also found in our bodies: the phospholipids and the sterols. While these two groups are only a very small percentage of our total lipids, they also have important functions. Because they have the unique ability to dissolve in water and fat, phospholipids help move other lipids in and out of cells, along with the hormones and vitamins they may contain.

The most common phospholipid is lecithin, made in the liver. It’s not necessary to take lecithin as a supplement; most lecithin supplements are deactivated by normal digestion before they can be useful, anyway. Lecithin is also manufactured as an emulsifier for foods, allowing fats and water to be mixed together in products like salad dressings, mayonnaise and chocolate.

Sterols are lipids that look like rings instead of chains. Everyone knows about cholesterol, but the sterols also include sex hormones and Vitamin D. Cholesterol is an important part of the structure of cell membranes. In infants and small children it’s critical to brain development and the protective covering of nerves. Cholesterol is made in the liver and is also found in animal foods.

Now that we have the science out of the way, it’s easier to more fully explain the importance of lipids in our diets.

Fats are a necessary component in our daily intake. They carry vitamins to our cells, keep us warm, can be used for energy and make our cells stronger, protecting them from other molecules that might otherwise cause destruction in our bodies.

Fats also make foods taste better! The problem is the high amount of saturated fats we eat in our refined and manufactured foods. Eliminating fats from most diets is unwise because we deprive our bodies of the necessary elements for normal growth and development. On the other hand, we only need a certain amount of fat in our diets to perform these important functions. Too much fat gets stored under our skin, around our organs and in our arteries.

One of the best ways to keep the necessary lipids in your family’s diet is to eat whole grains, nuts and seeds, and to use unprocessed oils. Try to avoid the frequent use of convenience foods, which often add fat for flavor and texture, and lower your meat consumption, changing from large cuts of meat to strips or pieces, as in stir fry. Adults should also drink skim or 1 percent milk to reduce their saturated fat intake, leaving the whole milk to the toddlers and 2 percent to older children.

Vegetarian families can get all the lipids they need by eating a variety of whole grains, nuts and oils while eliminating many of the saturated fats from their diets. Nutritionists are recommending that most of us eat less meat, adding dried peas and beans as an alternative. If you prefer to keep meat consumption in your meal plan, use lean meats like skinless chicken, turkey and pork, very lean beef and fish.

A little prevention for your family now will have a big impact on health in the years to come and give your children lifelong healthy habits.

Susan M. Leisner RD, IBCLC, RLC Nutritionist & Lactation Consultant