Major Lipids and Digestion

Essential fatty acids

Linoleic acid

Linolenic acid

Linoleic acid

18 C atoms, 2 cis double bonds, omega-6 FA

Linolenic acid

18 C atoms, 3 cis double bonds, omega-3 FA

Metabolism of Linoleic acid

Addition 2 carbons to make arachidonic acid then transitions to omega-6 eicosanoids. Inflammation and BV constriction.

Metabolism of Linolenic acid

Two carbons added to make eicosapentaenoic acid then can become docosahexaenoic acid with addition of two more carbons OR can ve converted into omega-3 eicosanoids. Anti-inflammatorym stimulate BV dialation, inhibit blood clotting.

FAs are conditionally essential in babies since…

They cannot produce adequate amounts of enzymes needed to make arachidonic acid and DHA.

This can be fed to babies thorugh breastmilk or formula.

Dietary sources of FAs

Canola, Safflower, Sunflower, Corn, Olive, Soybean, Palm, Peanut, Coconut oils

Margerine

Pork and Beef fat

Butter

Glycerides can be…

Mono-

Di-

or Tri-

Triglycerides

Hydrophobic

Body’s richest energy source (9 kcal/g)

Lipolysis

Triglycerides dissasembled into glycerol and FAs.

Lipases

Lipoprotein and Hormone-sensitive

Lipoprotein lipase

Removes FAs from triglycerides circulating in the blood.

Hormone-sensitive lipase

Removes FAs from triglycerides in adipose tissue

Adipose tissue stors excess energy in…

Adipocytes.

Phospholipids are made up of…

A glycerol molecule bound to 2 fatty acids and a polar head group. Pho

phospholipids are found in…

Cell membranes.

Phospholipids are responsible for…

Cellular metabolism

Eicosanoid production

Carrying of hydrophobic substances

Food sources of phospholipids:

Naturally in most foods.

Added to some foods, like mayo, to prevent separation.

Sterols are made up of…

Multi-ring structures that are free or bound to FA by ester linkages.

Sterols consist of:

Cholesterol and Cholesteryl ester

Cholesterol is found in:

Bile acids, membranes, and steroid hormones.

Cholesteryl ester is found in:

Membranes.

Cholesteryl esters are responsible for…

Carrying FAs in blood.

Sources of cholesterol:

Nearly every tissue in the body can make it from glucose and FAs.

Animal-derived foods such as shellfish, meat, butter, eggs, and liver.

Most digestion of triglycerides occurs in the…

Small intestine.

Lipids are emulsified in the…

Small intestine.

Long-chain FAs go into enterocytes and are reassembled into…

Triglycerides and phospholipids.

Long-chain FAs are incorperated into…

Chylomicrons.

Chylomicrons in the blood deliver FAs to cells via…

Lipoprotiein lipase.

Chylomicron reminants are taken up by the…

Liver.

Excess chylomicrons are taken up by the liver and are…

Broken down to be reused or recycled.