Health 230 (basic human nutrition) Queens University

kcalorie

a unit by which energy is measured (1 kcal = amount of heat necessary to raise the temperature of 1 kg of water 1°C). 1 kcalorie = 1 kilocalorie = 1 kcal =4.184 kilojoules = 1 "Calorie."

Distribution Ranges (AMDR)

45-65% of our total kcalories should be derived from carbohydrates

20-35% of our total kcalories should be derived from fat

10-35% of our total kcalories should be derived from protein

DRIs (Dietary reference intakes)

include EARs (estimated average requirements), RDAs (Recommended Dietary Allowance), AIs (adequate intakes), and ULs (upper Intakes). When referring to a value from the DRIs, you should indicate which value you are referring to

Estimated Energy Requirement (EER).

The EER is set to satisfy the "average dietary energy intake (kcalories per day) that will maintain energy balance in a person who has a healthy body weight and level of physical activity". The EER has been set to be less generous than nutrient RDAs is to ensure that the average person does not exceed their caloric needs.

Six classes of Nutrients

Inorganic nutrients: Minerals and water

Organic nutrients: Carbohydrates, lipids (fats), protein and vitamins.

Only carbohydrates, lipids and proteins are energy yielding

Differences between current & previous food guides

Private meetings were not held with the food and beverage industry when revising the food guide.

It does not have serving sizes and a recommended number of servings based on age and sex like the previous version of the food guide

"Eat a variety of healthy foods each day", "have plenty of vegetables and fruit", "eat protein foods", "make water your drink of choice" and "choose whole grain foods". Canada's Food Guide also includes recommendations about food choices and eating habits.

Changes to food labels

Changes include adding potassium to the nutrition facts table and removing vitamin A and vitamin C. The serving size will be more consistent for similar foods and sugar-based ingredients will be grouped together so you can see where the total sugar falls in the list of ingredients. Sugar will also have %DV indicated on the nutrition facts table allowing Canadians to judge if there is a little or a lot of sugar in the product. The amount of calcium and iron are now given in mg and not just as a percent daily value. (see image)

How to calculate calories from servings

A food label tells us that each serving of Happy Morning cereal has 110kcals, 23 g of carbohydrates, 2 g of protein and 1 gram of fat. We know that each gram of carbohydrate provides 4 kcal.

Therefore: 23g X 4 kcal/g = 92 kcal/serving of cereal

What is the percent of calories from carbohydrates in one serving of cereal?

= 92 kcal (carbohydrate calories/serving) ÷ 110 kcal (total kcal/serving)

=0.83636 x 100 (to get %)

=84% kcalories from carbohydrates

Canadian Nutrition Claims

In Canada we have two types of Nutrition and Health claims on food labels:

Nutrient content claims highlight a nutrition feature of a food such as light, low, less, free.

Health claims highlight a relationship between consumption of a food or ingredient and a person's health. For example, a healthy diet low in saturated and trans fat may reduce the risk of heart disease.

There are 6 key diet planning principles.

Adequacy: A diet which meets energy and nutrient needs for health.

Balance: Balance helps to ensure adequacy.

kcalorie/Energy Control: Watch your overall intake of food and balance it with activity.

Nutrient Density: This principle refers to maximizing the number of nutrients in a food, while minimizing the number of calories

Variety: The more variety that you introduce into your diet, the more you will be able to optimize the amounts of nutrients that you ingest.

Moderation: Go ahead and eat your favourite foods, just do not overindulge.

Kcal values of energy nutrients

Carbohydrates: 4 kcal per gram

Protein: 4 kcal per gram

Fat: 9 kcal per gram

*Alcohol is a non-nutrient, however it yields 7 kcals per gram

Primary nutritional deficiency

It mainly occurs because a person doesn't get enough of certain vital nutrients and it can be resolved by eating foods or taking supplements to provide the missing nutrients

Secondary nutritional deficiency

It occurs when the body's ability to absorb nutrients is limited by a medical condition or illness like celiac disease, cystic fibrosis, lactose intolerance, pancreatic insufficiency and pernicious anemia.

Prebiotics:

Food components (such as fibres) that are not digested in the small intestine, but are used instead as food by bacteria to encourage growth and activity.

Probiotics:

living microorganisms found in foods that when consumed in sufficient quantities are beneficial to health. Kefir and many yogurts are examples of foods that contain probiotics.

Peristalsis

Wavelike muscular contractions of the GI tract that push its contents along, to occur. Peristalsis increases during eating, and decreases during periods of exercise and stress in response to both hormonal and neuronal cues.

Digestive secretions and their major actions

See table 3-1

Modes of Absorption at the Level of the Cell

Simple Diffusion: a nutrient can enter a cell freely and passively, analogous to 'walking through a wall,' eg: water, short and medium chain fatty acids.

Facilitated Diffusion: alternatively, a nutrient can enter a cell by binding to a special protein and be carried across the membrane, analogous to 'opening a door to pass through a wall,' eg: water soluble vitamins.

Active Transport: finally, a nutrient can enter a cell by binding to a special protein, and with the use of energy, be carried across the membrane, analogous to 'having someone open the door for you before walking through and entering the next room,' eg: glucose, some amino acids.

Hormones that regulate digestion

Gastrin: secreted from the stomach wall, in response to stomach distension. It stimulates the stomach glands to secrete hydrochloric acid.

Secretin: chyme in the small intestine stimulates the duodenal wall to secrete secretin. Secretin stimulates the pancreas to secrete its bicarbonate rich juices into the small intestine. It inhibits release of gastrin (therefore decreasing acid release).

Cholecystokinin (CCK): secreted from the intestinal wall, this hormone is secreted in response to the presence of fat or amino acids in the small intestine. It stimulates the pancreas to secrete its bicarbonate-rich and enzyme rich juices. CCK stimulates the gallbladder to secrete bile. CCK also slows GI tract motility.

Common Digestive Problems

Choking, Dysphagia, Vomiting, Diarrhea, Constipation, Reflux (GERD or Gastroesophageal reflux disease), Ulcers, Gas & Achalasia

Choking:

Occurs when a piece of food enters the trachea, instead of the esophagus which results in an inability to breathe.

Dysphagia:

A difficulty swallowing and it is often seen in the elderly and in those with neurological conditions such as stroke, ALS and Parkinson's disease.

Vomiting:

Occurs as a result of a relaxation of sphincters and the contraction of diaphragm and abdominal muscles, which propels food in the reverse direction. These reflexes occur in response to an increased stimulation of the vomiting center in brain.

Diarrhea:

Refers to the presence of frequent, loose, and watery stools which can occur in response to an infection, foodborne illness, digestion-resistant foods or lactose intolerance, side effects of medications, irritable bowel syndrome/inflammatory bowel disease (IBS/IBD), etc.

Constipation:

Refers to passing stools with difficulty, pain, and an increased amount of time. Common causes include stress, medications, and inadequate fibre. One can help prevent constipation with adequate water, exercise, relaxation, fibre and by not ignoring the defecation signal.

Reflux (GERD or Gastroesophageal reflux disease)

Heartburn, which occurs as a result of the relaxation of the cardiac (lower esophageal) sphincter. Wearing tight clothing, lying down after eating, medications, and smoking, may also aggravate it. If untreated and chronic GERD may lead to Barrett's esophagus where stomach-like mucosa replaces the epithelium of the distal esophagus during the healing phase of acute esophagitis

Ulcers

Ulcers in digestion are an erosion of the wall of the stomach or intestine. An ulcer may lead to bleeding, pain, iron deficiency, and infection. Some common causes/contributors include bacterial infection, namely helicobacter pylori, the use of ibuprofen (even non-abusive use) and other anti-inflammatory drugs, and any physiological disorders that cause excessive acid secretion.

Gas

Includes belching, which results from swallowing air. Belching can be due to the use of dentures, drinking carbonated beverages, chewing gum, or eating too fast. Occasionally, it may be a sign of gallbladder disease, or a peptic ulcer. Intestinal gas is due to bacterial generation of nitrogen, methane, carbon dioxide, hydrogen, and oxygen.

Achalasia

Achalasia refers the failure of the lower esophageal sphincter to relax during the swallow thereby causing the esophagus to become distended due to build up of food in the esophagus. it is uncommon

Foodborne infection:

Caused by eating foods contaminated with infectious microbes

Food intoxications:

Caused by eating foods containing natural toxins, or microbes that produce toxins

The 4 main principles to help prevent food-borne illness

Clean - Wash hands and surfaces often, keep a clean safe kitchen.

Separate - Don't cross contaminate

Chill - Refrigerate foods promptly (keep cold foods cold - less than 4 C

Cook - Heat food to proper temperatures, keep hot foods hot.

Avoid the danger zone (4-60 degrees C is called the danger zone, because it is at this temperature where bacteria multiplies most readily).

Monosaccharides

Glucose is often considered to be the the most important monosaccharide. It is also known as 'blood sugar' and dextrose (present in sports drinks). Glucose is the chief source of energy for the brain, emphasizing why carbohydrates are such an important nutrient. Without enough glucose in our blood, we would die.

Fructose is the sweetest monosaccharide. It occurs naturally in fruit and honey, and it is also added to soft drinks and cereal.

Galactose. The least sweet. It rarely occurs free in nature but may be found in fermented milk products such as aged cheese or yogurt.

Disaccharides

Disaccharides are pairs of the monosaccharides

Maltose is composed of two glucose molecules, and is generally formed as a result of starch breakdown.

Sucrose, however, is present in many foods, and is more commonly known as table sugar. It is composed of one molecule of glucose and one molecule of fructose

Lactose is found most commonly in milk and dairy products. It represents 5% of milk by weight, and 30-50% of milk's energy. It is composed of one molecule of glucose and one molecule of galactose.

condensation reaction

Refers to the combining of two reactants to yield a larger product by creating a bond between them. This reaction also results in the production of a water molecule, by combining hydrogen (H+) from one molecule with a hydroxyl group (OH-) from the other. The chemical reaction that occurs when forming a disaccharide is an example of a 'condensation' reaction.

hydrolysis reaction

Results in the splitting apart of a large reactant (eg: maltose) to yield two products (eg: two glucose molecules). This reaction involves a water molecule as well. The water molecule is split into the hydrogen and hydroxyl group needed for the resulting monosaccharides.

Glycogen

Glycogen is a storage form of carbohydrate, composed of chains of glucose molecules found in the liver. It is only present in significant amounts in animal tissue (including humans) and is not found in plants. It is not considered a dietary source of carbohydrate, even if present in animals, because of rapid hydrolysis of animal glycogen occurs during the slaughtering process.

Starch

This form of complex carbohydrate represents the storage form of carbohydrate in plants. Similar to glycogen, it is composed of chains of glucose, though in different formations

Soluble Fibre

Gums, pectins and some hemicelluloses are members of the soluble fibre family. Soluble fibre is found in apples, citrus fruits, oats, barley and legumes. Soluble fibre delays GI transit, providing bulk and satiety. Soluble fibre also delays glucose absorption into the blood preventing large changes in blood glucose levels. Lastly soluble fibre can lower blood cholesterol levels by binding to bile, causing the bile to be excreted with feces

Insoluble Fibre

Cellulose, many hemicelluloses and lignins, which are found in wheat bran, corn bran, whole grains, cabbage, and carrots, are members of the insoluble fibre family. Insoluble fibre accelerates GI transit (promoting bowel movements), and delays glucose absorption.

Fibres

Fibre is generally considered a nonstarch polysaccharide because it is mainly composed of chains of glucose but humans lack the enzymes to digest it. Fibre forms the structural components of plants (eg. celery stalk). Again, similar to glycogen and starch, fibre is composed of chains of glucose (and/or xylose, mannose, etc.) The characteristic that sets fibre apart is the nature of the bond between each glucose molecule.

Enzymatic digestion of starch

Begins in the mouth, where amylase is present in saliva. Amylase breaks down polysaccharides (chains of glucose) into smaller polysaccharides and disaccharides. Mechanical digestion of fibre occurs in the mouth (crushing and chewing), but no enzymatic digestion of fibre occurs.

In the stomach, enzymatic digestion of starch ceases, and products of starch and fibre are mixed with acid. The majority of carbohydrate digestion takes place in the small intestine. Pancreatic amylase enters the small intestine and breaks polysaccharides into shorter glucose chains and disaccharides. Disaccharidases, produced by and present on the intestinal cells, cleave disaccharides into monosaccharides.

Type I diabetes

is an insulin-dependent form, where that person's pancreas is unable to produce sufficient amounts of insulin to allow for adequate cellular glucose uptake. It usually occurs early on in life and its etiology is unknown.

Type II diabetes

Type II diabetes is more common, and is not insulin-dependant. In Type II diabetes the cells are generally less responsive to the insulin therefore glucose uptake is limited. A primary risk factor for developing Type II diabetes is obesity, hence, it is a largely preventable.