Nutrition Exam 3

Which of the following is not a nutrient?

Phytochemicals

Lipids/fats contain __ kcal/gram

9

What is the daily recommended intake of carbohydrate, as a percent of daily calorie intake?

45-65%

Carbohydrates contain ___ kcal/gram

4

Proteins contain ____ kcal/gram

4

What is the daily recommended intake of protein, as a percent of daily calorie intake?

10-35%

Which of the following nutrients gets absorbed into the lymphatic system?

Lipids

People with uncontrolled diabetes can develop high LDL cholesterol because they are unable to metabolize glucose for energy. That means that fat cells are catabolized for energy and these lipid particles need to be transported with cholesterol.

True

Gluconeogenesis from protein can lead to dehydration.

True

Which of the following is a major risk factor for osteoporosis?

Low carbohydrate diet

Low carbohydrate diets can result in ketoacidosis.

True

Low carbohydrate intake is a risk factor for osteoporosis.

True

Which of the following is not part of carcinogenesis?

Increased rate of protein anabolism

Saccharide is the chemical name for _____

carbohydrate

single saccharide

Monosaccharide

pair of monosaccharides

Disaccharide

“Simple” carbohydrates

Monosaccharides and Disaccharides

chain of monosaccharides

Polysaccharide

“Complex” carbohydrate

Polysaccharides

Monosaccharides

Glucose, Fructose, Galactose

Disaccharides

Maltose, Sucrose, Lactose

Glucose

Essential source of energy for the body (the brain, nervous system, and RBCs require it); All disaccharides and nearly all polysaccharides contain glucose

Fructose

The sweetest monosaccharide, commonly found in fruit and honey

Galactose

Usually found only in small amounts in food

Maltose

Glucose + glucose; Grains

sucrose

glucose + fructose, sweetest disaccharide, table sugar

Lactose

glucose + galactose, milk

polysaccharides

Glycogen, starches, fibers

glycogen

Storage form of energy in muscle and liver (not found in plants); Food is not a good source of glycogen; When you consume glucose, if you don’t need immediate energy then the body stores it as glycogen for temporary storage (long term storage is body fat)

Starches

Storage form of energy in plants; Grains, some root crops (potato and sweet potato), and some legumes (beans and peas); Very good source of energy

fibers

Provide structure to some plant parts like stems, trunks, leaves, and skins; Cannot be absorbed in the small intestine and provide almost no kcal; Unlike all other macronutrients, fibers do not enter the blood stream, so they end up intact in the large intestine; In the large intestine they get partially fermented by bacteria and produce gas (and small chain fatty acids)

Soluble Fibers

Dissolve in water to form a gel; Natural part of plants, but also used in food processing to provide texture and mouthfeel: pectins and gums; Fruits, vegetables, and whole grains; cardioprotective

Insoluble Fibers

Don’t dissolve in water; Fruits, vegetables, and whole grains; Promote colonic health

Carbohydrate digestion

all about reducing polysaccharides to disaccharides to monosaccharides

Step 1 of Carbohydrate digestion

In the stomach, gastric acid deactivates the salivary enzymes and breaks down the food. Stomach muscles mechanically churn the food. Fiber delays gastric emptying (provides feeling of fullness, slows rate at which glucose enters bloodstream)

Step 2 of Carbohydrate digestion

In the small intestine,
The pancreas delivers pancreatic amylase (enzyme) to continue breaking down polysaccharides into disaccharides.
Then the small intestine contributes maltase, sucrase, and lactase (more enzymes) to break down each disaccharide into monosaccharides.

Where does most of carbohydrate digestion occur?

Small intestine

Where does most carbohydrate absorption occur?

small intestine

Carbohydrate absorption

The monosaccharides get absorbed into the villi, to the bloodstream, then to the liver. The liver then converts fructose and galactose to glucose.

Fiber in Large intestine (digestion and absorption)

The fiber attracts water, which helps soften the stool for excretion. Bacteria also digest some of the fiber, which produces gas as a byproduct.

Options for remaining glucose in liver

Immediate energy, short-term energy storage, long-term energy storage

immediate energy from glucose

Liver sends glucose into the bloodstream; Pancreas releases insulin to allow glucose to enter cells

short-term energy storage from glucose

Liver converts glucose to glycogen; Liver stores some glycogen, and sends the rest to the bloodstream to reach muscles

Long-term energy storage from glucose

Liver converts glucose to body fat; Liver sends the body fat to adipose tissue throughout the body

Whole food

fiber intact

processed food

fiber removed

Glucose metabolism

When you consume high saccharide foods with little fiber, the glucose rushes into your bloodstream. The pancreas goes into overdrive to produce enough insulin to allow the glucose to be metabolized into the body’s cells. If this happens regularly, the body’s cells become overwhelmed with insulin, and become resistant to it.

Type II Diabetes

he body’s cells become overwhelmed with insulin, and become resistant to it; a result of obesity, which leads to a condition called “general inflammation” - inflammation damages the cells and makes them resistant to insulin

Type I diabetes

an autoimmune disease that causes the pancreas to lose its ability to produce insulin, <1% of people

Diabetes mellitus

diseases that impair glucose metabolism (3 types)

Type II diabetes

Developed condition in which the body’s cells become resistant to insulin, ~12% of people

Gestational diabetes

Developed condition in which the placental hormones counteract insulin, 4-9% of pregnancies

Glucose metabolism

Glucose is meant to be absorbed. High levels of chronically circulating glucose can lead to blindness, vascular damage, nerve damage, infections, cardiovascular disease, and eventually death. Since the body desperately needs energy, it breaks down muscle (protein) and generates ketone bodies. Ketone bodies are acidic, and lower the pH of the blood. The body then pulls calcium from the bones to raise the pH, which leads to osteoporosis.

Role of lipids

Source of energy and fat-soluble vitamins, Component of cell structures and hormones, Energy storage and body warmth (body fat), Protection of internal organs

2 types of lipids

Fatty acids and Glycerol

Secondary types of lipids

Triglycerides (3 fatty acids + 1 glycerol), Phospholipids (emulsifiers, water-soluble), Sterols (hormones, cholesterol)

saturated fatty acid (SFA)

no double bonds, fully saturated with hydrogen atoms, vary in length ex. 18:0

monounsaturated fatty acid (MUFA)

one double bond, one point of unsaturation, vary in length, ex. 18:1

polyunsaturated fatty acid (PUFA)

more than 1 double bond, more than one point of unsaturation, vary in length, ex. 18:2

Omega number

represents the position of the first double bond closest to the methyl group in a PUFA, ex. 18:2, n-6

Fewer double bonds, the better fatty acid chains can stack on top of one another

True

Digestion of lipids (mouth/stomach)

usually in the form of triglycerides; in the mouth, some fats melt a little; In the stomach, stomach muscles grind the fatty food into smaller particles and Gastric lipase breaks down particles a bit more.

Where does most lipid digestion occur

small intestine

Digestion of lipids (small intestine)

Lipids particles are too big to be absorbed into the lining of the small intestine, so they need to be reduced first. The gallbladder delivers the bile to the small intestine, which breaks up the large lipid particles. The pancreas and small intestine also contribute enzymes to further reduce the size of lipid particles. These small lipid particles are now called micelles, and are small enough to be absorbed into the lining of the small intestine.

What is bile made from?

cholesterol, a type of sterol

Where is bile made? stored?

made in liver, stored in gallbladder

Absorption of lipids

micelles still need to pass through the lining of the small intestine and into the bloodstream, but they are insoluble in the water based bloodstream; micelles get coated in other compounds (cholesterol, phospholipids, and proteins,) while they’re still in the wall of the intestine. Now they’re called chylomicrons.

Transport of Lipids

chylomicrons are too large to fit through the nearby blood vessels that lead to general circulation. Take a detour through the lymphatic system which transports them into the bloodstream via a larger opening known as the thoracic duct. Now they’re in general circulation. Muscle and adipose tissue remove the fatty acids for energy and other purposes, and then the liver scavenges the remaining chylomicron components. The liver combines these chylomicron remnants with more cholesterol, and proteins to create low density lipoproteins (LDL), which are needed by the rest of the body to synthesize hormones and support cell membranes.

LDL cholesterol

The tissues use some, and any that remains in the bloodstream accumulates and hardens, creating plaque. As the plaque builds up it can lead to hypertension, stroke, and cardiovascular disease.

hdl cholesterol

scavenges cholesterol that was left behind in the bloodstream (from LDL) and brings it back to the liver

Saturated fatty acids

high ldl, low hdl

unsaturated (cis) fatty acids

low ldl, high hdl

trans fatty acid

Using industrial processes, cis fatty acids can become trans fatty acids by moving the hydrogen atoms to opposite sides of the chain. This makes the chain straighter, which means that it stacks easier (used in processed foods to provide firmness and extend shelf life)

Hydrogenated oils are the same thing as trans fatty acids

False, full hydrogenation makes it a saturated fat

Trans fats FDA

In 2013, the FDA banned industrial trans fats from all food, regulation took effect in 2020

unsaturated (trans) fatty acids

very high ldl, lowers hdl

cholesterol

Cholesterol from food is not the main source of serum cholesterol. Cholesterol in the arteries is due to overconsumption of saturated and trans fatty acids, which causes the liver to overproduce LDL.

Essential Amino acids

9, the body cannot synthesize them so they must be supplied by the diet

non-essential amino acids

11, the body can synthesize them from the essential amino acids

Synthesis of amino acids

These 20 amino acids are combined into chains, in different combinations, to form hundreds of thousands of different proteins. Tens of thousands of genes code for these proteins, which make every person’s array of proteins different. Suboptimal nutrition means that genes can’t code for all of the proteins that the body needs.

Peptides

chains of amino acids

Dipeptide

2 amino acids

tripeptide

2 amino acids

polypeptide

more than 3 amino acids, most proteins

Roles of proteins descriptions

Structural materials: growing, repairing, and replacing tissue. Enzymes: some of these enzymes during our discussions on digestion, Other enzymes are needed for building tissues, proteins can be anabolic or catabolic. Hormones: substances that provide messages/signals that initiate physiologic functions. Acid base regulators: Maintain balance between the acids and bases within the body’s fluids. Transporters: carry nutrients, oxygen, and other components throughout the body. Antibodies: Proteins that are designed to destroy specific antigens, human body needs to be exposed to these antigens in order to learn how to produce antibodies. Energy Source: body can use protein as a source of energy during insufficient glucose intake (gluconeogenesis).

Role of proteins

Structural materials, enzymes, hormones, regulators of fluid balance, acid base regulators, transporters, Antibodies, energy source

Digestion and absorption of amino acids

In the stomach, gastric acid and enzymes break down the peptides into smaller chains. This continues in the small intestine until individual amino acids remain. The amino acids are absorbed directly into the lining of the small intestine, to the bloodstream, and to the liver, and to general circulation.

Metabolism of amino acids

4 options once in the liver:
1. Reassembled into proteins and used to make nonessential amino acids; 2. Used to make other compounds, like enzymes, hormones, antibodies, transporters; 3. Used to make glucose when energy intake is inadequate; or 4. Used to make body fat when energy intake is excessive

Metabolism of amino acids (ammonia)

Ammonia is produced as a byproduct of amino acid metabolism, which is highly toxic. The greater the protein intake, the more ammonia is produced. The liver combines ammonia with carbon dioxide to produce urea, which is much less toxic. Then it sends it out into the bloodstream, and the kidneys remove the urea. The urea needs to be suspended in water, so the kidneys draw in water (why water needs increase with increased protein intake)

factors that contribute to the protein quality of food

Digestibility and amino acid composition

Digestibility

plants contain certain components that reduce the amount of nutrients that are absorbed vs. excreted. Proteins from animal foods are 90-99% digested, whereas proteins from plant foods are 70-90% digested

Amino Acid composition

Animal foods contain all nine essential amino acids, whereas plant foods don’t. a protein can only be synthesized if all requisite amino acids are in the body, not just some of them.

Complimentary foods

foods that, when combined, contain all essential amino acids. Can be consumed throughout the day rather than at each meal.

Alcohol production

produced by fermenting carbohydrates in anaerobic conditions. Fermentation is achieved by exposing carbohydrates to yeast, which is a fungus. This reaction produces ethanol and carbon dioxide.

Alcohol digestion

In the stomach, alcohol dehydrogenase (enzyme) breaks some of it down. Women don’t produce as much of this enzyme as men, which means they absorb more alcohol. The rate of gastric emptying depends on whether food is also in the stomach.

Alcohol Absorption

In the small intestine, alcohol gets absorbed rapidly. Since it can’t be stored, and its toxic if it hangs around too long, it gets absorbed and metabolized before all other nutrients.

Alcohol Metabolism

In the liver, alcohol gets exposed to more alcohol dehydrogenase, which continues to break it down. 90% of alcohol is metabolized into carbon dioxide and water, and 10% is excreted unmetabolized through the lungs, urine, and sweat.

Metabolic effects of alcohol

This process requires exclusive use of niacin (vitamin B3) to facilitate these reactions. But niacin is critical for facilitating energy metabolism so energy production is halted and diverted to energy storage (body fat). Some of this body fat is subcutaneous, but some is visceral and accumulates in the liver. As fat builds up in the liver it fails to function properly, and nutrients can’t be absorbed, leading to malnutrition. Alcohol itself also destroys dietary protein in the liver, which leads to immunity depletion and infection. Over time, the cells of the liver die and become scarred, which is called fibrosis, and the more severe condition is called cirrhosis.

Effects of Alcohol

As energy metabolism halts, the body breaks down fatty acids and proteins to form ketone bodies. This, along with other byproducts of alcohol metabolism, causes a pH imbalance in the bloodstream. Over time, this can cause inflammation of the joints. To correct this, calcium gets pulled from bones, which leads to osteoarthritis and eventually osteoporosis. Eventually, overconsumption of alcohol affects nearly every part of the body (can even cause permanent brain damage).

Benefits of Alcohol

Light to moderate alcohol consumption can provide some cardiovascular benefits. Alcohol has blood-thinning properties, which mildly increases flow and lowers blood pressure. This can reduce the risk of cardiovascular disease and stroke when consumed in moderation. Social relaxation. Neurologic relaxation: stimulates the release of serotonin and dopamine.