NTR 401 Exam 1

What is nutrition?

The science of food, the nutrients and the substances therein, their action, interaction, and balance in relation to health and disease, and the process by which the organism ingests, absorbs, transports, utilizes, and excretes food subtances

What are present day nutrition concerns?

- Overnutrition

- Optimal nutrition

Undernutrition related issues

- Anorexia nervosa

- Osteoporosis

- Iron deficiency anemia

Assessing nutritional status

- Anthropometric

- Biochemical

- Clinical

- Dietary

- Environmental

Carbohydrates

- Composed of C, H, O

- Provide a major source of fuel for the body

- Basic unit is glucose

Lipids

- Composed of C, H, and few O

- Basic unit is fatty acid

- Triglyceride is the major form of lipid

Proteins

- Composed of C, H, O, N

- Basic unit is amino acid

- Makes up bones, muscles, and other tissues

- 9 essential amino acis

- 11 nonessential amino acids

Vitamins

- Needed in small amounts

- Yields no energy

- Either fat or water soluble

Minerals

- Trace minerals < 100 mg/day

- Major minerals > 100 mg/day

- Yields no energy

Water

- Vital to life

- Makes up majority of our body weight

- Yields no energy

Alcohol yields how many calories?

7 kcal/g

Phytochemicals

Physiologically active compounds found in plants that may provide health benefits

Zoochemicals

Physiologically active compounds found in foods of animal origin that may provide health benefits

What are dietary guidelines?

- Reflect what scientific experts believe is the most accurate and up-to-date scientific knowledge about nutrition

- Designed to meet nutrient needs while reducing risk of chronic diseases

- Also guide government nutrition programs (WIC and SNAP), research, food labeling and nutrition education

Dietary guidelines key recommendations for 2025

- Follow a healthy dietary pattern at every life stage

- Customize and enjoy nutrient dense food and beverage choice to reflect personal preferences, cultural traditions and budgetary considerations

- Focus on meeting food group needs with nutrient dense foods and beverages and stay within calorie limits

- Limit food and beverages higher in added sugars, saturated fat, and sodium and limit alcoholic beverages

ChooseMyPlate guidelines

- To translate science into practical terms

- To help people meet the nutritional needs for carbohydrates, protein, fat, vitamins, and minerals

- Provides a foundation to eating

MyPlate recommendations

- Enjoy your food, but eat less

- Avoid oversized portions

- Make half your plate fruits and vegetables

- Make at least half your grains whole grains

- Switch to fat-free or low fat 1% milk

Dietary reference intake (DRI)

- Nutrient recommendations to prevent deficiencies and chronic diseases in healthy individuals

- Nutrient recommendations are updated every few years

- DRI set for all vitamins and minerals

Standards under the DRI

- Estimated average requirements (EARs)

- RDAs

- Adequate intake (AIs)

- Tolerable upper intake levels (ULs)

Estimated average requirements (EARs)

- Nutrient intake estimated to meet the needs of 50% of the individuals in a certain age and gender group

- Can only be set if there is an accurate method for measuring whether intake is adequate

- Used to calculate RDA

Recommended dietary allowances (RDAs)

- Recommended intake of nutrients that meet the needs of almost all healthy people of similar age and gender

- Amount to prevent deficiency and chronic diseases

- Improvement in health is not expected if you consume more than RDA amounts

- Goal is to eat close to the RDA level average for a week

RDA formula

RDA = EAR x 1.2

Adequate intakes (AIs)

- Not enough information available

- Based on observe or experimentally determined estimates

- Set for some vitamins, choline, some minerals, essential fatty acids, fiber

- For children under 1

Tolerable upper intake levels (ULs)

- Maximum level of daily intake without causing adverse health effects

- Chronic daily use

- Not a goal, but a ceiling

- Based on combined intake of food, water, supplements, and fortified food

- Niacin, magnesium, zinc and nickel toxicity is unlikely from food

Adequate macronutrient distribution ranges

- For carbohydrate, protein, fat and essential fatty acids

- A range of intake

- Listed as a % of energy (Ex: Carbs 45-65% of total calories)

- Amounts needed for health promotion and reduced risk of chronic disease

Uses for DRIs

- Guiding nutrition programs (SNAP, National school lunch)

- Nutrition labeling

- Nutrition policies (dietary guidelines)

- Diet planning for the healthy population

DRIs are not appropriate for

- Malnourished individuals

- Malabsorption diseases

- Those receiving dialysis

Digestive system

- Digests food, absorbs nutrients and excretes waste

- Controlled by hormones and the nervous system

- Houses bacteria (microbiota) in the microbiome

Digestive system and the immune system

Digestive system has a role in the immune system:

- Acts as a physical barrier

- Produces immune components

Major and accessory organs of the GI tract

- Mouth and salivary glands

- Esophagus

- Stomach

- Small intestine

- Large intestine

- Rectum

- Anus

How long can food remain in stomach?

- 2 to 3 hours

- Longer for large meals

How long does digesting food remain in the small intestine?

3 to 10 hours

How long do contents remain in the large intestine?

72 hours or longer

Sphincters

- Ring like muscles that work like valves to control flow of contents

- Prevent contents from moving through the GI tract too quickly

- Some prevent contents from going the wrong way

Lower esophageal sphincter

Prevent backflow (reflux) of stomach contents into the esophagus

Pyloric sphincter

Controls the flow of stomach contents into the small intestine

Hepatopancreatic sphincter

Control the flow of bile and pancreatic juice from the common bile and pancreatic dusts into the small intestine

Ileocecal valve

Prevent the contents of the large intestine from reentering the small intestine

Anal sphincters

Prevent defecation until the person desires to do so

Saliva

- Produced by the mouth

- Dissolves taste-forming compounds that aid in swallowing, digestion, and protection of teeth

Mucus

- Produced by the mouth, stomach, small and large intestine

- Protects GI tract cells and lubricates digesting food

Enzymes (amylases, lipases, proteases)

- Produced by the mouth, stomach, small intestine and pancreas

- Breaks downs carbs, fats, and protein into forms small enough for absorption

Acid (HCl)

- Produced by the stomach

- Promotes digestion of protein, destroys microorganisms, and increases solubility of minerals

Bile

- Produced by the liver and stored in gallbladder

- Aids in fat digestion by emulsifying fat

Bicarbonate

- Produced by the pancreas and small intestine

- Neutralizes stomach acid when it reaches small intestine

Hormones

- Produced by the stomach, small intestine and pancreas

- Regulate food intake, digestion and absorption

Where and how does digestion in the body start?

- Mouth

- Teeth tear and grind food into smaller pieces

- Saliva is mixed with food particles to create bolus

What does saliva contain?

- Mucus to help lubricate and hold bolus together

- Lysozyme to kill bacteria

- Amylase to break down starch

What does the stomach secrete?

- Gastric juice to aid in the digestive process

- This juice is released when we see, smell, taste, or think about food

What do gastric juices contain?

- Hydrochloric acid HCl from parietal cells

- Pepsinogen, an inactive protein digesting enzyme

- Gastric lipase from chief cells

- Gastrin, a hormone that controls the release of hydrochloric acid and pepsinogen

Hydrochloric acid (HCl)

- Inactivates the biological activity of ingested proteins

- Destroys harmful bacteria and viruses

- Dissolves dietary minerals

- Converts pepsinogen into active enzyme pepsin

What else does the stomach secrete?

- Mucus from mucous cells

- Lubricates and protects stomach from being digested by HCl and pepsin

- Production relies on prostaglandins

- Use of aspirin and other nonsteroidal anti-inflammatory drugs (NSAIDs) can inhibit prostaglandin production, resulting in a reduced mucus barrier and potential damage to the stomach wall by stomach acid

Stomach and contraction

- Contraction of the muscle layers in the stomach thoroughly mixes food with gastric secretions

- Transforms solid food into chyme

- Pyloric sphincter controls flow of chyme into small intestine and backflow of bile into stomach

- Glucose dependent insulinotropic peptide helps slow the release of chyme into the small intestine

What else does the stomach produce?

- Intrinsic factor

- Needed for the absorption of vitamin B12

Small intestine and digestion

- Major site of digestion and absorption

- It is divided into duodenum, jejunum, and ileum

- Interior of small intestine has circular folds and fingerlike projections called villi and microvilli

- Circular folds cause chyme to move slowly through a spiral path which helps mix chyme with digestive juices and bring nutrients into contact with villi

What are villi lined with?

- Enterocytes

- Secretes enzymes and absorb nutrients

What other secretions does digestion in the small intestine depend on?

- Pancreas

- Liver

- Gallbladder

Accessory organs and digestion

- Liver, gallbladder, and pancreas

- Work with small intestine

- Secretions are delivered to the small intestine through the common bile duct and pancreatic duct

- Ducts come together at the hepatopancreatic sphincter and empty into the duodenum

Liver produces what?

- Bile

- Contains cholesterol

What does the gallbladder do?

- Stores and concentrates bile

- Bile is reabsorbed into the ileum and returned to the liver

- Enterohepatic circulation

- Small amount of bile is not reabsorbed and is excreted into feces

What does the pancreas produce?

- Pancreatic juices

- Sodium bicarbonate neutralizes acidic chyme

- Pancreatic amylase digests starch

- Pancreatic lipase digests fats

- Proteases digest proteins

Gastrin

Triggers release of HCl by stomach

Secretin

Stimulates release of pancreatic bicarbonate

Cholecystokinin (CCK)

Stimulates release of bile and pancreatic enzymes

Glucose-dependent insulinotropic peptide (GIP)

Inhibits gastric acid secretion and slows the release of chyme into the small intestine

Absorption in the small intestine

- Passive diffusion

- Facilitated diffusion

- Active transport

Passive diffusion

Nutrients move from an area of high concentration to an area of low concentration

Facilitated diffusion

Movement from a high concentration area to a low concentration area, but a carrier protein is needed

Active transport

Requires a carrier protein and energy

Major sites of absorption along GI tract

- Stomach

- Small intestine

- Large intestine

Nutrients absorbed in the small intestine are delivered where?

- Cardiovascular system

- Lymphatic system

Depending on the solubility of the nutrient

Water soluble nutrients are transported where?

Cardiovascular system

- Proteins

- Carbs

- B-vitamins

- Vitamin C

- Short chain fatty acids

- Medium chain fatty acids

How are water soluble nutrients absorbed?

Directly into the capillary beds in the villi

Water soluble nutrients are transported where before circulation?

Liver via the hepatic portal vein system

Liver will then:

- Metabolize nutrients

- Store nutrients

- Send nutrients into circulation

Lymphatic system

- Provides an alternative route to the bloodstream for large molecules including most fats and fat soluble vitamins

- Lacteals in villi transport nutrients to thoracic duct which leads into the left subclavian vein

How does the small intestine empty into the large intestine?

- Ileocecal valve

- About 5% of nutrients escape absorption in the small intestine to enter large intestine

3 main functions of large intestine

- Houses microbiota to keep GI tract healthy

- Absorbs water and electrolytes (sodium and potassium)

- Forms and expels feces

Gut microbiota

- The ileocecal valve prevents bacteria in the large intestine from migrating into the small intestine

- Many of the bacteria are beneficial

- Antibiotic treatment, radiation therapy, surgery and some diseases reduce the amount of bacteria which disrupts the normal balance of beneficial and pathogenic bacteria

Beneficial bacteria can

- Synthesize Vitamin K and biotin

- Aid lactose digestion

- Ferment some fibers and starches

- Fermentation creates short-chain fatty acids that can be absorbed and used as an energy source in the colon

Probiotics

- Live microorganisms that colonize the large intestine

- Found in fermented foods and supplements

- Can prevent diarrhea, food allergies, irritable bowel syndrome, inflammatory bowel disease

Prebiotics

- Nondigestible food ingredients

- Promote the growth of beneficial bacteria

- Inulin found in wheat, onions, garlic, asparagus, bananas

- Resistant starch found in unprocessed whole grains, seeds, legumes, fruit

When digestive processes go awry

- Heartburn

- Gastroesophageal reflux disease

- Nonalcoholic fatty liver disease

- Gallstones

- Food intolerances

- Constipation

- Diarrhea

- IBS

- IBD

Heartburn and gastroesophageal reflux disease

- Heartburn occurs when stomach acid backflows into the esophagus

- 2 or more times per week signals GERD

Symptoms of GERD

- Heartburn

- Hoarseness

- Trouble swallowing

- Coughing

- Gagging

- Nausea

Serious complications of GERD

- Weight loss

- Ulceration

- Bleeding

- Anemia

- Risk of adenocarcinoma of esophagus

Contributing factors to heartburn and GERD

- Alcohol use

- Overweight

- Smoking

- Pregnancy

- Some foods: citrus fruits, chocolate, caffeinated drinks, fatty and fried foods, garlic, onions, spicy food, tomato based food

Treatment for heartburn and GERD

- Eat small meals, low in fat

- Avoid trigger foods

- Wait two hours after a meal before lying down

- Lose weight

- Stop smoking

- Limit alcohol intake

- Elevate the head of the bed at least 6 inches

Ulcers

- Small erosions of the top later of cells in the stomach or duodenum

- Complications include bleeding and perforation

Main causes of ulcers

- Infection with Helicobacter pylori

- Heavy use of NSAIDs

Ulcer symptoms

- Gnawing or burning pain in stomach region

- Nausea

- Vomiting

-Loss of appetite

- Weight loss

Ulcer treatment

- Antibiotics for those infected with H. pylori and proton pump inhibitor to suppress acid production

Recommendations to prevent ulcers from occurring or recurring

- Stop smoking if you smoke

- Avoid large doses of aspirin, ibuprofen, and other NSAID compounds unless advised otherwise

- Limit intake of coffee, tea and alcohol

Nonalcoholic fatty liver disease

- Occurs when liver cells store excess fat, which may cause liver swelling, inflammation and scarring

- Excess alcohol intake also can cause these changes

- Individuals with NAFLD do not abuse alcohol

- When inflammation or scarring is present, the condition is known as nonalcoholic steatohepatitis (NASH)

- Occurs in adults and children, higher in those with obesity, diabetes, or insulin resistance

NAFLD or NASH symptoms

- Hard to diagnose because many individuals have no symptoms

- Fatigue

- Nausea

- Poor appetite

- Weight loss

- Jaundice

- Diffuse pain by liver under right rib cage

Treatment for NAFLD and NASH

- Gradual weight loss

- Reduction in calorie intake

- Avoiding all alcohol

- Eating a nutritious diet

Gallstones

- Develop when cholesterol and bile pigments from crystal-like particles related to slow gallbladder motility and bile composition

- Surgical removal

Gallstones symptoms

- Most people do not have symptoms but can include

- Intermittent pain in right upper abdomen

- Pain between shoulder blades or near right shoulder

- Nausea

- Vomiting

- Gas

- Bloating

Celiac and non-celiac gluten sensitivity

- Consuming gluten causes damage to GI tract

- Gluten is found in wheat, rye and barley

- Gluten free diet for life needed

IBS

- More common in women

- Cause is unknown but stress and diet may play a role

IBS treatment

- Low fat, frequent, small meals

- Avoid food triggers

- FODMAPS elimination diet