Nutrition: Lipids: Triglycerides, Phospholipids, and Sterols

Oxidized Fat

Fat in food becomes rancid and develops an unappetizing odor and taste. Unsaturated fatty acids that have the cis double-bond arrangement, especially polyunsaturated fatty acids, are very susceptible to oxidation

Lipid Consumption Patterns

Although the DRI committee has not established an RDA or AI for total fat intake (for people over 1 year of age), the Acceptable Macronutrient Distribution Range (AMDR) for fat is 20 to 35% of total caloric intake.5 According to the Dietary Guidelines, adults should emphasize foods that are rich sources of polyunsaturated and monounsaturated fatty acids, such as fish, nuts, and vegetable oils.

Secretin

A hormone secreted by the small intestine (duodenum) in response to low pH (e.g., from stomach acid). It promotes the release of bicarbonate from the pancreas to act as a buffer.

Modifiable Risk Factors

-Diabetes Mellitus -Elevated blood cholesterol (especially LDL cholesterol) -Excess body fat -Hypertension -Physical inactivity -Tobacco use or exposure -Unhealthy diet -Untreated sleep apnea

Embolus

A thrombus or part of a plaque that breaks free and travels through the bloodstream.

Cardiovascular Disease (CVD)

-Includes heart disease (coronary artery disease, or CAD), stroke, and diseases of the blood vessels. -86 million of Americans are living with some form of CVD. -In 2014, nearly half of all deaths were because of a heart disease or/and stroke. -Heart diseases kills someone in the United States a person every 84 seconds.

Lipid's function

-Structure of the plasma membrane that surrounds each cell. -Absorb fat-soluble vitamins and phytochemicals -Cushion the body against bumps and blows -Form and maintain cell membranes -Form body contours -Insulate the body against cold temperatures -Produce steroid hormones -Provide and store energy (triglycerides) -Provide food flavor, texture and aroma, therefore, it makes food more appetizing.

How many Americans adults have hypertension, according to the American Heart Association?

80 million American adults.

Recommendations about the intake of saturated fat

American Heart Association guidelines recommend limiting saturated fat intake to less than 10% of total energy by replacing foods that are rich sources of long-chain saturated fat with foods that contain high amounts of unsaturated fat.

Atherosclerosis

(athero: lipid, sclerosis: hardening). Chronic process that negatively affects artery function. Results in decreased arterial blood flow.

Long chain fatty acids

14-24 carbons

Short Chain Fatty Acids (SCFA)

2-4 carbons

Medium chain fatty acids

6-12 carbons

How many grams of fat Americans consume per day?

80 grams

Homocysteine

Amino acids are the chemical units that comprise proteins. the substance is a toxic by-product of protein metabolism. Higher-than-normal blood levels of homocysteine may injure arterial walls. Thus, people with homocysteinuria have a higher risk of developing CVD than persons who do not have the condition.

Sterols

Are lipids that have a more chemically complex structure than a triglyceride or phospholipid.

Atherosclerosis and hypertension

Atherosclerosis contributes to the development of hypertension, a chronic condition characterized by abnormally high blood pressure that persists even when the person is relaxed. A hypertensive patient will have a heart that needs to work harder to circulate blood through abnormally stiff arteries. Elevated blood pressure can cause hardened arteries to tear or burst, causing serious bleeding or sudden death, depending on the artery's location and size. Hypertension is typically a result of poor diet, lack of physical activity, stress and family history.

Thrombus

Blood clots that form easily, they get fixed together and remain in place, disrupting blood flow. It can partially close the artery's lumen (opening of the artery) and if this happens with the arteries that nourishes the heart, the muscle does not receive enough oxygen and nutrients to function properly. The person might feel pain chest pain, especially when the heart beats faster (emotional distress or physical activities). However, if the thrombus completely blocks blood flood to a section of the heart muscle, the muscle dies. This is called myocardial infarction, or commonly known as heart attack.

Phospholipids are important components of a cell membrane

Cell membranes are composed of a double layer that is mostly phospholipids. This allows the cell membrane to be flexible and function properly. Phospholipids are also needed for normal functioning of nerve cells, therefore, the brain.

Bile Salts

Compounds that enhance digestion and absorption by emulsifying lipids in the watery environment of the small intestine.

Gallstones

Develop in the gallbladder or bile ducts, making one of the most common digestive diseases in the United States. Gallstones can be small or large. When a gallbladder contains stones, it contracts and the person feels pain in the right upper part of the abdomen. When the stone moves out of the duct, the discomfort ends. If the body is unable to remove the stone or stones itself, a cholecystectomy might be required. This surgical procedure removes the diseased gallbladder.

Fat malabsorption

Diseases that affect the intestinal tract can interfere with digestion and cause poor absorption of fat. Diarrhea, steatorrhea, and rapid weight loss are the most common signs.

Monounsaturated fatty acids (MUFAs)

Generally lower blood LDL cholesterol without reducing HDL cholesterol levels.

Blood clotting

Healthy and normal response to blood vessel injury that prevents bleeding excessively.

Fatty Acids

Most lipids have it. It provides energy for muscle and most cells. They are made of hydrocarbon chain, a chain of carbon atoms bonded to each other and to hydrogen atoms. One side is called omega or methyl end and it is composed of 1 carbon and 3 hydrogen molecules. The other end is called carboxylic acid and it is the fatty acid molecule (C=O-OH). Scientists identify the fatty acid by the number of carbon atoms and the type of bond between carbon atoms and hydrocarbon chain.

Arteriosclerosis

Reduced arterial wall flexibility. It is a symptom or by-product of atherosclerosis.

Phospholipids

Similar to triglyceride, except that one of the fatty acids is replaced by a chemical group that contains phosphorus, and often nitrogen. However, they are different because phospholipids are partially water soluble. The phosphorus portion of the molecule is hydrophilic (attracts water). On the other hand, a phospholipids molecule also has a hydrophobic portion (avoids watery substances). This structure can serve as an emulsifier.

Prostaglandins (class of eicosanoids) that comes from an essential fatty acid.

Stimulates uterine contractions, regulates blood pressure, mediates the immune system's inflammatory response.

Emulsifier

Substance that keeps water-soluble and water-insoluble compounds mixed together

How does atherosclerosis develop?

When arterial lining gets injured by oxidation, infection or nutrient deficiency, an immune response is producing inflammation. When blood LDL concentration is high, inflammation triggers WBC. These become heavily laden with oxidized LDL particles (foam cells). The cholesterol rich foam cells become trapped in the artery wall and becomes arterial plaque.

Are Trans Fats important?

Whole milk and whole-milk products, butter, and meat naturally contain small amounts of trans fats. Even though the body can use trans fats for energy, there are non-essential lipids. They have no positive health effects from consuming them. Actually, trans fats raise blood levels of unhealthy cholesterol and that presents a risk for heart disease. Most of the trans fat in processed food, also called artificial trans fat, resulted form partial hydrogenation.

Who are more at risk of gallstones?

Women, specially over 40 years old. -Patients with family history. -Patients who are overweight or lose weigh rapidly. -American Indians and Mexican Americans commonly have the highest rates of gallbladder disease in the United States. -When the gallbladder does not work properly or is removed, steatorrhea can show up This is when presence of lipid is found in the stool.

omega fatty acids

type of polyunsaturated fat that is required by the body; the numbering of the carbon omega starts from the methyl end (end farthest from carboxylic end)

Enterohepatic Circulation of Bile

- 98% of the bile salts are reabsorbed in the ileum -The liver incorporates the bile salts into new bile (the recycle of bile is called enterohepatic circulation). -Plants contain soluble fiber that interfere with the cholesterol and bile absorption, therefore, it also reduces blood cholesterol levels.

Lipid Storage Diseases

Genetic conditions that cause lipid accumulation in cells, which damages tissues. Enlarged spleen or liver, swollen abdomen, skeletal disorders, and swollen lymph nodes are sings of this disease. Gaucher Disease is caused by a deficiency of an enzyme involved in lipid metabolism. This create lipid accumulation in bone marrow, liver, kidneys, lungs, spleen and even the brain. Gaucher disease is fatal and some individuals can survive to the early teenage years and young adulthood.

Lipids

Include triglycerides, phospholipids, and sterols (such as cholesterol). They do not dissolve in water, but with acetone and alcohol they do.

Why is DHA and EPA important for infants?

Infants require them for nervous system development and growth. Deficiencies can led to scaly skin, hair loss, and poor wound healing. The AI for alpha-linolenic acid for men is 1.6 g/day and for women is 1.1 g/day. The AI for linoleic acid is 17 g/day for men and 12 g/day for women wo are between 19 and 50 years old. These amounts can be made with vegetable fat (2-3 tablespoon) such as canola and soybean oils. You can also eat fatty fish, such as salmon and tuna, at least twice a week.

Stroke

It happens when blood clots block an artery in the brain and brain cells that are nourished by the vessel, dying. When an artery to a limb is blocked, the tissue in that extremity dies, causing gangrene. If the area is large, amputation might be needed to prevent life-threatening infection.

Cholesterol

It is found only in foods derived from animals. Egg yolk, liver, meat, poultry, and dairy products made from cream or whole milk are rich sources of the lipid.

Lipoproteins

clusters of lipids associated with proteins that serve as transport vehicles for lipids in the lymph and blood. Lipoproteins contain different percentages of lipid and protein. Low-density lipoprotein (LDL) carries more cholesterol in the bloodstream than the other lipoproteins. In comparison, chylomicrons carry the most triglycerides.

Essential fatty acids (EFAs)

fatty acids that must be consumed in the diet because they cannot be made by our body. Examples: Linoleic Acid and alpha-linolenic acid. Linoleic acid is transformed in the body to arachidonic acid (AA) and alpha-linolenic acid to 2 omega-3 acids (eicosapentaenoic or EPA and docosahexaenoic or DHA)

Partial Hydrogenation

It's a food manufacturing process that adds hydrogen atoms to some unsaturated fatty acids in liquid vegetable oil creating a PHO (Partially Hydrogenated Oil). The partial hydrogenation process converts many of the oil's naturally occurring cis fatty acids into trans fatty acids. Therefore, vegetable oil can be made into a solid fat to be stored for longer periods of time and is less likely to undergo oxidation.

"Mono" or "poly" fatty acids

Mono: only one double bond linking 2 carbon atoms. Poly: Two or more double bonds in their hydrocarbon chains.

Lipid Digestion

Most lipids are completely insoluble in water. This characteristic makes lipid digestion, absorption, and transport more complicated than that of carbohydrates because these three processes involve considerable amounts of water.

Lipid Digestion

Triglycerides and phospholipids need to be broken down by lipases, an enzyme that breaks down lipids. An inactive lipase is mixed with the saliva when you are eating and once the food enters your stomach, the organ's acidic environment activates the lipase, and the breakdown occurs. However, the primary site of lipid digestion is the small intestine.

Nonmodifiable Risk Factors for CVD

-Family History -Increasing Age -Male sex (more probable to experience heart attacks) -Race/ethnic background (Americans of African, Mexican, or Native American ancestry are more likely to have heart disease)

Arterial Plaque

-Fatty buildup in the artery. -Interferes with the circulation because it narrows the artery and may even block the opening fully (lumen). -Plaque makes arteries walls more rough, and this should be smooth. This makes clots most likely to form. -When plaques rupture, repairing the rupture also involve clot formation, and these can be life threatening.

Lipid transportation

Fatty acids, glycerol, monoglycerides, and phospholipid fragments are reassembled into triglycerides and phospholipids within the absorptive cells of the small intestine. As chylomicrons circulate through the body, lipoprotein lipase (LPL), an enzyme in the walls of capillaries, breaks down the triglycerides in the chylomicron into fatty acids and glycerol.

lipid digestion in small intestine

The fatty chyme leaves the stomach and enters the small intestine, stimulating certain intestinal cells to secrete the hormones cholecystokinin (CCK) and secretin.

Lipid Absorption

The majority of lipid absorption occurs in the small intestine, particularly in the duodenum and jejunum. Glycerol, fatty acids, monoglycerides, cholesterol, and phospholipid fragments are the end products of lipid digestion.

Trans Fats

unsaturated fatty acids that have at least one trans double bond in their chemical structure, rather than the more common cis configuration (two carbon atoms that are connected by a double bond, each having a hydrogen atom on the same side of the hydrocarbon chain). Fats that contain a high proportion of trans fatty acids are more solid at room temperature than those with a high proportion of cis fatty acids.

Cholecystokinin (CCK)

A hormone secreted by the small intestine (duodenum) in response to the presence of fats. It promotes release of bile from the gallbladder and pancreatic juice from the pancreas, and reduces stomach motility. It also triggers the sphincter that controls the flow of bile and pancreatic juice into the duodenum to open.

Plant Sterols and Stanols

These lipids occur naturally in small amounts in many grains, fruits, vegetables, nuts, seeds, and legumes. Because their chemical structures are similar to cholesterol's, plant sterols and stanols compete with cholesterol for intestinal absorption, which reduces the amount of cholesterol that is absorbed. As a result, consuming foods that contain plant sterols and stanols may be an effective way to lower elevated blood cholesterol levels, a risk factor for developing heart disease.

statins

Drugs used to lower cholesterol in the bloodstream. It reduces the elevated blood lipid levels.

Saturation of fatty acids

Fatty acids are saturated if there are no carbon double bonds, meaning, each carbon is completely filled with hydrogen atoms. Unsaturated if there are one or more double bonds where hydrogen atoms are missing.