Chapter 5: Fats

What are lipids?

• 34% of energy in the human diet

• Dietary fat is stored in adipose cells

• Structral fat(in the human body)

  • organ replacement

  • protection

  • preserves heat

• Textural properties

  • Ice cream or crispy baked goods

• Highest calorie intake

• CF also deficient in fat solubale vitamins

What are the three classes of lipids

• Triglercerides

• Phospholipids

• Sterols

Describe triglycerides

• Made from the same elements as CHO

  • more kal dense than CHO

  • 3 Carbon backbone attached to Fatty ACids

  • Account for 98% Fat in food

Describe phospholipids

• Similar structure as triglycerides

  • One of Fas attached to Carbon backbone is a phosphate groups

  • Emulsifiesrs

  • Prostaglandins

  • Lectithin

Sterols

• Waxy substance

• carbon, hydrogen and oxygen molecules are arranged in a ring

• cholesterol

• Bile salts

• Sex hormones

• Vitamin D

Fatty Acids

• Chains of carbon atoms with hydrogen atoms attached

  • Chains will vary in length

  • natural FA will have an even number of carbon chain

    • typically 4 and 24 in length

  • Long-chain fatty acids

    • containinning more than 12 carbon atom

  • Medium-chain fatty acids

    • contain 6 to 12 carbon atoms

  • Short-chain fatty acids

    • up to 6 carbon atoms

  • Rarely free in nature and almost always linked to other molecules

Saturated fatty acids

• SFA

• medium chain triglycerids (MCT)

• Palm kernel oil, coconut oil

• poultry eggs, dairy products, and vegetable oils

Monounsaturated fatty acid

MUFA

• unsaturated

• canola and olive oil,

• most nuts

• avocado

Polyunsaturated fatty acids

• PUFA
  Walnuts, ground fish, soybean oil, canola oil chia and hemp seeds

• The degree of saturation will be influence the stability of fat

• PUFA are most likely to go rancid (spoiled), compared to any other fat

• Food manufacturers may use the process of hydrogenation to prolong shelf life

What is hydrogenation?

Hydrogenation is the process that adds hydrogen atoms to heart healthy polyunsaturared oils to saturate some of the double bonds so that the resulting product is less susceptible to rancidity and has improved function

Cis /Trans Fat

• Trans fat is recommended to be limited from commercial ususe partial or light hydrogenated fats as an alternative

  • Increasing Saturated fat consumption

  • FDA requires trans fat amount on the nutrition facts label

What is Cholesterol?

• Apart of the sterol lipid group

• Occurs in the tissues of all animals

  • Found in all cell membranes and myelin

  • Found exclusively in animals

    • Liver and egg yolks are the richest sources

  • Does not provide calories

What are some examples of foods high in cholesterol?

Beef brain, chicken liver, egg yolk, shrimps, cheeseburger, chicken legs

What is the difference between “good” and “bad” cholesterol

“Good” and “bad” cholesterol refers to the lipoprotein

• packages that move cholesterol throughout the blood

• Lipoproteins

  • transport protein from fat and cholesterol through the blood

  • Lipoproteins

    • transport protein from fat and cholesterol

  • LDL→ we want this lower, can modify with good diet, exercise

  • VLDL

  • HDL→ healthy

Where does digestion of fats begin?

• Limited chemical digestion starts in the mouth and stomach

  • Lingual lipase and gastric lipases

• When the fat passes the duodenum, which reases a hormone, cholectoskin

  • which stimulatees the gall bladder to release Bile

• Most digestion occurs in Small Intestine

  • Pancreatic lipase

  • Small amount of fat excreted in the feces

How does absorption work?

• About 95% of consumed fat is absorbed in the duodenum

• Small fat particles are absorbed directly through the mucosal cells into capillaries

  • Combine with Albumin and transport to the liver via the portal vein

How does the absorption of larger fat particles work?

• namely, monoglycerides and long chain fatty acids is more complex

• 1. Micelles

  • that delivers the fat to the intestines

  • 2. Recombine into triglycerides

• 3. Chylomicrons distribute dietary lipids throughout the body

What is Fat Catabolism?

Catabolism of fatty acids increases when carbohydrate intake is adequate(e.g while on a very low calorie diet)

• Or catabolism of fatty acids is unavailable (e.g in the case of uncontrolled diabetes

• Ketones are formed

• Fatty acids cannot be reassembled to make glucose

• Not the ideal choice of fuel for glucose-dependent brain cells. nerve cells and red blood cells

What is Fat Anabolism?

• Newly absorbed fatty acids recombine with glycerol to form triglycerides that end up stored in adipose tissue or glycogen in humans

• Fat stored in glycogen represents the body’s largest and most efficient energy reserve

• Adipose cells have virtually limitless capacity to store fat

• For fat reserves, one pound of fat provides 3500 calories

Describe some fat functions in foods

• Unique flavor

• Transfers heat to rapidly cook food

  • example: frying

• Absorbs flavors and aromas of ingredients to improve overall taste

• Insoluble in water=unique texture

On the MyPlate with Fat, where are the greater amounts of fat?

• Dairy and Protein

What are full fat products?

• Fat in dairy products is predominately saturated and full fat products have more cholesterol than in lower fat options

What is fat free?

• Milk, yogurt, and cheese provide virtually no fat

What is reduced fat?

• Mid-range

• Some fat and cholesterol removed yet retain some of the mouth feel characteristic of whole milk

“Red meats” vs “white meats”

• Lower fat in poultry meat

  • white poultry versus dark meat

  • removing poultry skin

• Fats differ with different cuts in meat

  • leanest cuts

  • beef: loin and round

  • lamb/veal": loin or leg

  • pork: tenderloin or center loin chop

Shellfish

• lower in fat content but contain considerable amount of cholesterol

Wild game

• very lean, less fat content

• bison, venison, elk, ostrich, pheasant\(skinless), rabbit, and squirrel

• Processed meats

  • usually higher in fat content versus comparing protein and CHO

  • sausage and hot dogs

Nuts

• higher in fat content

• higher in monosaturated and polyunsaturead fats

• rich in alpha linolenic acid(ALA)

  • walnuts, chia seeds, ground flax seeds

What is essential fatty acid deficiency

• body cannot make essential fatty acids

• symptoms of essential fatty acid deficiency include growth failure, reproductive failure, scaly dermatitis and kidney and liver disorders

• Populations at risk: children consuming low fat diets, AN, lipid free PN, people diagnosed with fat malabsorption syndromes

Fats in Health Promotion

• Limit total fat and go for unsaturated fats

  • Most effective way to limit total and saturated fat and increase unsaturated fats may be with a plant based diet

• Limit cholesterol

  • Cholesterol intake becomes less important when saturated fat intake is low

• What about fish oils?

  • American Heart Association suggests healthy people eat at least two serving of fish per week