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Based on the questions we get, it seems that people are commonly confused about what types of fat should be included in their diet and how much. Quite a lot is known about the effects of fats on human health. Even so, some important issues are still being unraveled. Get the skinny on dietary fat
Most every fat has something good about it, along with potential downsides. Yet, those marketing a particular fat, oil or higher-fat food will naturally stress the positive attributes of their product, conveniently ignoring any shortcomings.
But, before we get into some really fascinating questions about fat and health, we need to briefly cover "Fats 101."
Question: What are fats?
Answer: The term "fat" is sometimes misinterpreted. Fats belong to a category of food components called lipids, which also include cholesterol and phospholipids such as lecithin. Fats that are liquid at room temperature are called oils; if they are solid at room temperature (i.e. butter), they are called fat.
When evaluating research on the types and amounts of fat in a healthful diet, oils and solid fats are lumped into one category called lipids or fats.
Ninety-five percent of all dietary fats and oils are made up of chemical compounds called triglycerides. And as the name implies, each triglyceride contains three fatty acids. The types of fatty acids make one type of fat different from another.
Q: What are fatty acids and how are they classified?
A: Very simply, fatty acids are chains of varying lengths of carbon atoms. A fatty acid contains a large amount of carbon and hydrogen and a smaller amount of oxygen. It is the length of these chains and the level of saturation that determines how a fatty acid affects body functions and health.
Q: What is saturation?
A: Saturation means that the carbon atoms along the fatty-acid chain are saturated with hydrogen atoms. Monounsaturated and polyunsaturated fatty acids, as their name implies, are not completely saturated with hydrogen atoms. Solid fats contain proportionately more saturated fatty acids than liquid fats, which contain a greater proportion of monounsaturated or polyunsaturated fatty acids.
Q: Popular media sources often recommend consuming monounsaturated fats for health. Which oils are monounsaturated?
A: Not so fast! As with nearly everything in nutrition, health is about moderation and proportion. Black-and-white thinking, or the concept of "good or bad" foods, has no place in nutrition. Both saturated and unsaturated fatty acids have various levels of health benefits and risks.
Also, the length of fatty acids makes a difference in the physiological effects of a fat. Too much or too little of various fatty acids can cause imbalances in physiological functions such as blood pressure regulation and blood clotting.
Saturation is only one variable that makes a fat beneficial or harmful. And remember, all fats contain various proportions of saturated and unsaturated fatty acids.
Save this article for a quick review before next week's column, when we sink our teeth into some really interesting fat questions.
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Alan Titchenal, Ph.D., C.N.S., is a sports nutritionist in the
Department of Human Nutrition, Food and Animal Science,
University of Hawaii-Manoa.Joannie Dobbs, Ph.D., C.N.S., is a food and nutrition consultant
and owner of Exploring New Concepts, a nutritional consulting firm.
She is also responsible for the nutritional analyses
indicated by an asterisk in this section.