Fats, the body’s reserve source of energy, protect organs and vessels, maintain body heat, and perform other functions depending on their type. Fats provide:
- Energy source. Fats are vital energy reserves that come in concentrated form, releasing heat at nine kcal/g compared to carbohydrates’ rate of four kcal/g. fats keep the body warm and slow down digestion, making us feel full.
- Essential nutrients. Fats provide the body with essential fatty acids and cholesterol. They also carry fat-soluble vitamins, helping cells absorb these nutrients.
- Cell membrane and tissue structure. As integral parts of cell walls, fats facilitate the transport of nutrients across membranes. Their web-like structure supports and protects vital organs, provide a protective coating around nerve fibers and aid in the relay of messages between nerves.
What you should know about fats
- Lipid is a term applied to all fats and fat-related compounds. It is combined with other terms to refer to a variety of fat-related health conditions. Triglyceride is the chemical term for fats referring to the composition of fat—glycerol tied to fatty acids.
- Fatty acid, the basic building block of fats is either saturated or unsaturated. “Saturated” means it binds all the hydrogen it can, making it more solid and heavier. Saturated fats come from animals. Excess intake of saturated fat increases the level of cholesterol and the risk of antherosclerosis, the hardening and blockage of arteries. Unsaturated fat is lighter, in liquid form, and comes mostly from plants. These healthy fats—monosaturated fats containing one unfilled spot for hydrogen, and polyunsaturated fats, which have two or more—help remove cholesterol from artery walls and improve blood flow.
- Transfatty acids (trans fats) are created by hydrogenerating—or adding hydrogen atoms to fatty acids so they remain solid at room temperature—vegetable oils. Hydrogenerated vegetable oils are added to canned or processed foods, commercially fried foods, baked goods, and margarine to lengthen their shelf life. Excess intake of trans fats raises the risk of heart disease.
- Essential fatty acids are polyunsaturated fatty acids that the body cannot produce in sufficient amounts, thus, they must come from the food intake. Lack or essential fatty acids in the diet can lead to deficiency diseases.
- Linoleic, linolenic, arachinodic, eicosapentaenoic (EPA), and docosahexaenoic (DHA) are the essential fatty acids needed by the body for brain development, tissue formation, cholesterol metabolism, blood clotting, muscle tone and cardiac performance. Only linoleic acid is derived solely from food, specifically polyunsaturated vegetable oils. The rest are synthesized in the body.
- Lipoprotein or cholesterol is fat (lipid) coated in protein. Fats and water don’t mix so fats cannot freely circulate in the blood (which is partly water), but protein-wrapped fat can. Cholesterol is used to create some hormones, synthesize vitamin D, and form bile, which is secreted by the liver to aid digestion and absorption of fats and fat-soluble vitamins. The body produces small quantities of cholesterol stored in the liver, skin, intestines, and other tissues.
- Low-density lipoproteins (LDL) carry fats and cholesterol to cells. High density lipoproteins (HDL) bring fats and cholesterol to the liver for breakdown and excretion.
- HDL is also known as “good” cholesterol. HDL lessens the risk of blood vessels getting clogged with fat by taking cholesterol to the liver. LDL or “bad” cholesterol is distributed to cells, building up plaque in the walls of arteries that clogs the passage of blood to the heart and brain—this increases the risk of heart attack and stroke.
Sources, recommended intake
Saturated fats are found in animal-based products including red and white meat—red meat has more saturated fats—lard, shortening, egg yolk, and dairy products such as butter, margarine, and whole milk.
Unsaturated fats come from plants—avocado, peanut and other legumes, cashew and other nuts, pumpkinseeds, and oils from canola, olives and sesame seeds. Polyunsaturated fats are found in corn oil, soybean oil and sunflower oil.[pq]Dietary experts recommend a fat intake of no more than 20 to 30 percent of the recommended kcal per day. That translates to less than 70 grams of fat for school-age kids.[/pq]
Too little fat in the diet—at 10 percent or less—isn’t good since the body would not have enough essential fatty acids to function normally.
About two-thirds of fat intake should come from unsaturated or plant-derived fats. Dietary cholesterol should be limited to 300 mg a day.