Utilization

  • Energy Storage
  • Insulation
  • Body structure
  • Cell membranes
  • Protection
  • Essential fatty acids (linoleic and linolenic acid)
    • controlling inflammation, blood clotting, and brain development
  • Hormones & bile salts
  • Vitamin carrier (Fat soluble vitamins A, D, E, K)
  • Palatability and satiety of foods

 


 Monounsaturated | Polyunsaturated | Omega-3 | Saturated | Trans-unsaturated

 

Monounsaturated Fats

  • Liquid at room temperature
  • Found in canola oil, olives, olive oil, nuts, peanut oil, and avocados
    • See Exchange List and Comparison of Fats
  • Preferred in the diet
    • Can lower LDL (bad cholesterol) and maintain HDL (good
      cholesterol) if substituted for other less healthy fats
    • Contain essential fatty acids which help to reduce cholesterol deposits

Polyunsaturated Fats

  • Liquid at room temperature
  • Largly found in safflower, sesame, corn, cottonseed, and soybean oils
    • See on Exchange List
  • Also found in meats, milk, eggs in form of Arachidonic Acid
  • Linked to decrease in mortality (Hu 2005)
  • Large intake may increase the risk for some types of cancer

Omega-3 fatty acids

  • Type of Polyunsaturated fatty acid
  • Benefits
    • Maintains cardiovascular health
      • reduce triglyceride levels
    • Maintains mental clarity
    • Anti-inflammatory properties
      • may help arthritis and lupus
      • helps lubricate joints
  • Omega-3 sources
    • Fish and fish oils
      • Salmon, mackerel, lake trout, herring, sardine, white (albacore) tuna, cod, halibut, mahi-mahi, catfish, flounder, tilapia, bluefish, whitefish
        • Particularly wild caught
      • See Omega-3 content in Seafoods
      • Up to 12 oz (340 g) of fatty fish (low mercury) per week recommended
      • Oily fish may contain harmful chemicals, such as dioxins and PCBs
        • UK Food Standards Agency recommendation (FSA 2004)
          • men eat no more than four portions of oily fish per week
          • women and children no more than two
    • Walnuts, soybeans, beans, winter squash, avocados
    • Seeds
      • Flaxseed, kiwi seed, perilla seed, sacha inchi seed, and chia seeds
    • Oils
      • Canola, soybean, walnut, echium, and flaxseed oils
      • High lignan flaxseed oil Canola Oil contain precursors of Omega-3 Fatty acids (DHA and EPA)
    • Small concentrations in green leafy vegetables (kale, collard greens) and certain algae
    • Foods fortified with DHA from algae
      • fish get their DHA from algae
    • Grass-feed animals
      • Grass-feed animals provide more omega-3 fats, whereas grain fed animals provide more omega-6 fats
    • Supplements
      • Consider taking fish oil or flaxseed oil if diet is insufficient in Omega-3
        • No mercury, dioxin, and PCBs often found in fish
        • Patients with congestive heart failure or chronic recurrent angina should not be urged to consume fish oil or more fish (Leaf 2006)

Omega-6 fatty acids

  • Family of unsaturated fatty acids
  • Too much Omega-6 promotes inflammation
    • Increases risk of coronary heart disease and other chronic illnesses
    • may counter anti-inflammatory effects of omega-3 fatty acids
      • must be accompanied by adequate Omega-3 to provide protective effects
  • Ratio of Omega-6 to Omega-3 in diet (Simopoulos AP 2012)
    • Recommended ratio is 2:1 to 4:1
    • Average Western Diet is 15:1-16.7:1
    • Early man’s diet was approximately 1:1
  • Sources
    • Plant based
      • cereals, some nuts, whole grains, and vegetable oils
    • Animal based (Arachidonic Acid)
      • meats, eggs, milk
    • Farm raised fish contain more Omega-6 fatty acids compared to wild caught fish
    • Omega-6 to Omega-3 ratios in oils:
      • Flaxseed Oil (1:3)
      • Canola Oil (2:1)
      • Olive Oil (13:1)
      • Corn Oil (46:1)

Arachidonic Acid

  • Arachidonic Acid is Omega-6, polyunsaturated fat
  • Regulator of localized muscle inflammation and is necessary for the repair and growth of skeletal muscle tissue via conversion to active components such as prostaglandin PGF2alpha.
  • Found in animal food including meats, organ meats, and eggs.
  • However, it can be produced by the body from linoleic acid, an essential fatty acid.
  • In some mammals, such as cats, lack the ability to produce signficant amounts of arachidonic acid, making it an essential part of their diet.

Trappe TA, Fluckey JD, White F, Lambert CP, Evans WJ (2001). Skeletal muscle PGF(2)(alpha) and PGE(2) in response to eccentric resistance exercise: influence of ibuprofen acetaminophen. The Journal of Clinical Endocrinology and Metabolism 86 (10): 5067–70.

Saturated Fats

  • Solid at room temperature
  • Found in animal fats
    • meat, dairy, eggs
  • Found in some plant sources
    • cocoa butter, coconut, palm and palm kernel oils
  • Saturated fats can be converted to cholesterol or LDL
    • Main cause of high blood cholesterol (American Heart Association)
  • Double risk of CHD for every 15% increase in saturated fat calories (instead of carbohydrate calories) (Hu 1997)
  • See Saturated Fats Exchanges and Additional Fat Exchanges

Trans-unsaturated fat

  • Processed foods and oils provide 80% of trans fats in diet
    • Examples
      • margarine (up to 15% trans fat by weight)
      • baking shortening (30% of trans fat)
      • partially hydrogenated and hydrogenated oil (up to 45% trans fat)
      • See Exchange List
    • Found in
      • fast foods and fried food
      • Peanut butter (partially hydrogenated)
      • snacks foods and many baked goods
        • replaces butter and lard
    • Created industrially through partial hydrogenation of plant oils
      • process developed in early 1900s
      • first commercialized as Crisco in 1911
    • Benefits
      • extends shelf life and decreases refrigeration requirements
      • less expensive than semi-solid oils such as palm oil
      • can be reused longer in deep frying without going rancid
      • baked goods look better, browns more evenly
      • vegetarians can consume foods made from vegetable trans fats as opposed to butter and lard
  • Animal sources only provide 20% of trans fats
    • in form of conjugated linoleic acid and vaccenic acid
    • naturally occurring amounts in meat and dairy products
      • 2-5% of total fat
  • Cooking oil’s smoke point
  • When cooking oil reaches its smoke point it will degrade, oxidize, and partially hydrogenate, creating trans fats
    • Olive oil, extra virgin: 375°F (190°C)
    • Canola Oil: 375-475°F (190-246°C)
    • Grape seed oil: 420°F (216°C)
    • Olive oil, extra light: 468°F (242°C)
    • Safflower oil: 510°F (266°C)
    • Avocodo oil: 520°F (271°C)
  • Health impact
    • Non-essential
    • Consumption increases risk of coronary heart disease (CHD)
      • Increased risk at 1 to 3 percent of total energy intake (Mozaffarian 2006)
      • Double risk in CHD for every 2% in trans fat calories consumed (instead of carbohydrate calories) (Hu 1997)
      • An estimated 30,000 and 100,000 cardiac deaths per
        year in the United States are attributable to the consumption of trans fats (Mozaffarian 2006)
    • Cholesterol effects
      • Increases LDL (bad cholesterol)
      • Lowers HDL (good cholesterol)
    • Example content
      • doughnut (medium): 3.2 g of TFA
      • french fries (large): 6.8 g of TFA
  • Recommendations
    • Trans fats be limited to less than 1% of overall energy intake (World Health Organization 2003, American Heart Association)
      • Example: consume less than 3 grams of trans fat on a 3000 Calorie diet

Also see Comparison of Dietary Fats


American Dietary Guidelines (2005)

  • A high fat intake (greater than 35% of calories)
    • associated with higher saturated fat intake
      • keep saturated fat below 10% of calories
    • more difficult to avoid consuming excessive calories
  • Low fat intake (less than 20% of calories)
    • increased risk of inadequate intakes of vitamin E and essential fatty acids
    • may contribute to unfavorable changes in HDL and triglycerides

Weight Management

  • Dietary fats are stored and mobilized easily
    • It takes more energy for the body to convert carbohydrates or protein to body fat than it does to convert dietary fat to body fat
      • see thermic effect of food
  • Typically, less calories are consumed when eating a low fat diet (Lissner 1987, Thomas 1992).
  • A reduction in dietary fat without a reduction in total calories or an increase of physical activity only produces small if any changes in body fat mass (Leibel 1992).

Effects on Endurance

  • High fat diets may limit endurance if carbohydrates are low and body is accustom to a higher carbohydrate diet.
    • After 2–4 weeks, physical endurance is not affected by ketosis as long as dietary fat remains high. (Phinney 2004).
    • A high fat diet may actually increase endurance in certain elite athletes particularly if they have adapted to such a diet
      • Studies are mixed as to whether it increases endurance
      • Ideal would be fat adaptation with high glycogen and intramuscular triglyceride stores
      • Fat adaptation occurs after five days of being on the high fat diet and persists during one day of carbing up (Burke 2000)
    • There is no net glucose synthesis from lipids except from glycerol portion – 10% by weight