Are Fats the Enemy of Humanity?

Which fats are truly dangerous to us, and which are not?

To understand the differences between various oils and fats, we need a brief and accelerated chemistry lesson. The good news is that it's not mandatory, and those who prefer not to delve too deeply can skip to the next paragraph.

Fats in food mainly consist of triglycerides, composed of a glycerol molecule linked to three molecules of fatty acids. Over 40 fatty acids exist, differing in length and saturation level (i.e., the number of double bonds in their carbon chains).

Fats in food come from either plant or animal sources. Animal fats are solid at room temperature because they contain numerous saturated fatty acids. Plant-based fats are generally liquids (like oil) at room temperature, as they have many unsaturated fatty acids. Exceptions include coconut and palm oil, which are high in saturated fatty acids and are therefore solid even at room temperature.

Too many people perceive fats as humanity's enemy, not always justifiably. Fats have numerous redeeming qualities. It's all about balance in life. That's how it is. Life is complex (but interesting!).

1. Fats provide a convenient and concentrated energy source (nine calories per gram).

2. Fats help in absorbing fat-soluble vitamins (vitamins A, D, E, and K) and carotenoids (beta-carotene found in carrots and lycopene in tomatoes), and they play a role in food texture and flavor creation.

3. Fatty acids play an essential role in the stability of cell membranes in the body, in signal transmission between cells, in the metabolism of carbohydrates and fats, and in regulating processes like fat storage, inflammation, insulin activity, and nerve functions.

4. Additionally, some fatty acids are as vital to the body as vitamins - our body cannot produce them independently, so they must be obtained from food.

Fatty acids in food are divided into four main categories: Saturated fatty acids - primarily found in animal foods, such as dairy and meat products, but also in coconut oil, palm oil, and cocoa butter.

Monounsaturated fatty acids - found in olive oil, canola oil, avocados, tahini, almonds, peanuts, hazelnuts, northern sea fish (mackerel, tuna, salmon, halibut), and meat products.

Polyunsaturated fatty acids - Omega 3: Alpha-linolenic acid is the most important omega-3 fatty acid. It is not produced in the human body, making it essential in our diet. A prolonged deficiency can lead to nervous system issues and growth impairments. Additionally, it has anti-inflammatory properties.

Food sources include: northern sea fish, walnuts, flaxseeds, and canola oil.

Omega 6: Linoleic acid is the most important omega-6 fatty acid. It is also not produced by the human body and is vital for a healthy diet. A prolonged deficiency results in rough, scaly skin and stunted growth.

Food sources include: vegetable oils such as corn oil, soybean oil, safflower oil, and sunflower oil.

Trans Fat

This fat is created during a food production process called hydrogenation, a chemical process that turns liquid plant oil (unsaturated) into a solid oil. Hence, it is also known as hardened plant fat. Using this type of fat allows for longer shelf lives of foods it is included in. However, there is a shocking side effect, as the process of turning liquid oil solid transforms healthy oil into ticking time bombs in our arteries.

Federal agencies in the United States have determined that trans fat is dangerous enough to our health that food companies are required to include nutritional labeling of trans fat content in foods starting from 2006. In the country as well, manufacturers will be required to state the amount of trans fat in food products.

Food sources include: hard margarine, baked goods, malawach, bourekas, frozen dough products, and fried foods.

Each oil contains a different ratio of fatty acids and is classified by the primary type of fat it contains. For instance, olive oil is considered monounsaturated because it contains 77% monounsaturated fatty acids, yet it also includes saturated and polyunsaturated fatty acids.

(The author is a clinical dietitian at Schneider Children's Medical Center from Clalit Health Services, and the creator of the "Personal Online Diet" program.)