Faculty of Medicine Introduction to Community Medicine Course

(31505201)

Unit 2 Nutrition and Nutrition Assessment and Diet

The Nutrients & their Categories.

By

Hatim Jaber MD MPH JBCM PhD

27-09-2017

المكتبيةالساعات

واالربعاءاالثنين , االحد

12-10من

Attention!!!!!!!!

• Sun 25-9 Introduction and Terminology used in nutrition

• Tue 27-9 The Nutrients & their Categories

• Thu 2 -10 Spectrum of public nutrition problems: Malnutrition & its Ecology and Common nutritional disorders in Jordan

• Tue 4-10 Assessment of Nutritional Status. Anthropometric Assessment.

• Thu 9-10 Breast feeding & Breast milk. Formula feeding

Presentation outline

Time

Nutrients classifications 08:00 to 08:10

Macronutrients and their functions 08:10 to 08:20

Micronutrients and their functions

08:20 to 08:40

Water , vitamins and minerals 08:40 to 09:00

Glycaemic index

09:00 to 09:15

Background definitions

• Nutrients: “Chemical substances in food that nourish the body by providing energy, building materials, and factors to regulate needed chemical reactions.”

• (Organic and inorganic complexes contained in food are called nutrients).

• Essential nutrients: Must be provided by food because the body does not produce them in sufficient quantities or can not make them at all.

• Nonessential nutrients: Healthy, well-nourished bodies can make them in sufficient quantities to satisfy their needs.

The Nutrients

Nutrients are classified into : • A. Macronutrients (carbohydrates, fats,

and proteins).

1. Provide calories for energy

2. Needed in large quantities

• B. Micronutrients (vitamins, minerals, and water).

Needed in smaller amounts

Six categories of nutrients

1. Carbohydrates: contain carbon, hydrogen, and oxygen combined in small molecules called sugars and large molecules represented mainly by starch.

2. Lipids (fats and oils): contain carbon, hydrogen, and oxygen as do carbohydrates, but the amount of oxygen is much less. Triglyceride is the main form of food fat.

1. Proteins: contain carbon, hydrogen, and

oxygen, plus nitrogen and sometimes sulfur atoms arranged in small compounds called amino acids. Chains of amino acids make up dietary proteins.

Six categories of nutrients (cont’d):

4. Vitamins: are organic compounds that serve to catalyze or support a number of biochemical reactions in the body.

5. Minerals: are inorganic elements or compounds that play important roles in metabolic reactions and serve as structural components in body tissues such as bone.

6. Water: is vital to the body as a solvent and lubricant and as a medium for transporting nutrients and waste.

about 45 essential nutrients

Energy and food

• The energy in foods is expressed as kilocalories. One kilocalorie represents the amount of heat it takes to raise the temperature of one liter of water 1°C

• A person needs about 2000 kilocalories a day to meet his or her energy needs. In common usage, people refer to kilocalories as calories, which is a much smaller energy unit:

1 kilocalorie contains 1000 calories.

Carbohydrates There are three types- sources of carbohydrates food sugar, starch and

cellulose

• 1- Sugar: Sugar is also called simple carbohydrate.

Fruits, honey and sugar are some sources of sugar.

• 2- Starch: starch is called complex sugar. Plants store energy in the form of starch. When we eat plant products containing

starch, our digestive system breaks down starch into glucose. This glucose is absorbed in blood and provides energy.

Some foods give carbohydrates to our body in the form of starch. These are cereals, potatoes, sweet potatoes etc.

Some other foods give carbohydrates in the form of sugar. For example sugar, honey, jam, jiggery, etc.

Starch and sugar are the main source of energy and essential for synthesis of certain non-essential amino acids

• 3- Cellulose: complex carbohydrates not digested but form the bulk of stools.

Carbohydrates

---Optimum requirement of carbohydrate in balanced diet 50-70%of total energy intake.

• One gram of carbohydrate gives four kcal.

• An adult person needs 400-420 gms of carbohydrates everyday.

Carbohydrates are classified into:

• Monosaccharide are seldom found free in nature and are the simplest form of carbohydrate.

• Disaccharides and polysaccharides consist of monosaccharide linked together.

• Also carbohydrates are classified into simple and complex carbohydrates.

Simple and Complex Carbohydrates

Simple

• Sugars and Starches

• Referred as nitrogen free extract (nfe)

• Come from cereal grains (corn, etc)

Complex

• Cellulose and lignin

• Called Fiber

• More difficult to digest

• Found mostly in roughages (hay, grass)

• Monosaccharides: 1. Glucose (blood sugar),

2. Fructose(fruit),

3. Galactose (milk)

• Disaccharides: 1. Sucrose (table sugar=glucose and fructose),

2. Lactose(milk- glucose and galactose),

3. Maltose

• Polysaccharides: (Starch in plants and Glycogen in human and animals)

1. Digestible: Amylose, Amylopectin, Resistant starch, Dextrins and Glycogen (animal carbohydrate)

2. Indigestible: dietary fibers: cellulose, pectin, gums….

Fibers • dietary fiber Nondigestible carbohydrates and

lignin that are Intact in plants. • functional fiber Nondigestible carbohydrates

either isolated from natural sources or synthesized; these may be added to foods and dietary supplements.

• total fiber The total amount of dietary fiber and functional fiber in the diet.

• soluble (viscous) fiber Fiber that dissolves in water or is broken down by bacteria in the large intestine.

• insoluble fiber Fiber that does not dissolve in water and is not broken down by bacteria in the large intestine.

Dietary Fiber and Functional Fiber

• Cellulose • Beta-glucans • Chitin and chitosan • Hemicellulose • Pectins, gums, and mucilages • Fructans • Algal polysaccharides • Lignin

Role of Fiber in Digestion and Absorption

• Prevent constipation

• Increase fecal volume

• Decrease GI transit time

• Slowed or decreased nutrient absorption

• Bind cholesterol and minerals

• Reduce the risk of cancer and GBS

• Modify serum lipid concentrations

Functions of Carbohydrates

• Give energy and feeling of fullness

• -increase the bulk of our food.

• -Spare proteins to perform other functions

• -Helps to make the food tasty.

• - Prevent ketosis

Proteins

Are nitrogenous compounds, composed of amino acids

Complete proteins: • Foods containing all the essential amino

acids Examples: fish, meat, eggs, milk, cheese

Incomplete proteins: • Foods that are missing some essential amino

acids Examples: Legumes, nuts, whole grains

• Proteins have an amino group, an acid, a hydrogen, carbon molecule and a carbon side chain.

• Protein means primary or first and are necessary for life.

• Amino means contains nitrogen (NH2).

• Proteins can also contain sulfur, phosphorus or iron.

Amino Acids and Protein

• Essential amino acids

• Nonessential amino acids

• 9 of the 20 amino acids are called essential amino acids because you must obtain them from the foods you eat since your body cannot make them.

Structure and Function of the 20 Amino Acids Required by Humans

Amino acids marked with an asterisk (*) are essential.

Structure and Function of the 20 Amino Acids Required by Humans–cont’d

Amino acids marked with an asterisk (*) are essential; those with a double asterisk (**) are essential in infants and in chronic diseases.

Structure and Function of the 20 Amino Acids Required by Humans–cont’d

Denaturation • Protein denaturation happens when a

protein changes its shape, usually uncoiling.

• This changes its function and properties.

• An egg is mostly liquid until cooked. Milk becomes yogurt or or cheese when acids or enzymes are added.

• Heat, acids, bases, alcohol, heavy metals, enzymes or other agents can cause denaturation.

Copyright 2005 Wadsworth Group, a division of Thomson Learning

Dietary Protein Quality

• Limiting amino acid • Net protein utilization • Protein digestibility corrected amino

acid score (PDCAAS) • Denaturation • Vegetable vs animal protein • Food processing • Complementary proteins

• High biological value protein(HBV protein): any HBV protein in adequate amount provides the body needs of amino acids ___ all animal proteins are HBV except gelatin

• Low biological value protein (lBV protein) where some of essential amino acids are either missing or of inadequate amount== all plant except soybeans

Reference protein

• Ideal protein – is protein that fulfils the following theoretical criteria:

- contains all essential amino acids in optimal amount for human being

- fully digestible and utilizable by the body

Reference Proteins

• Used data for highy digestible, high quality proteins - egg, meat, milk or fish

• For adults over age 19 the reference protein intake is 0.75 g/kg/day (RDA is 0.8)

• Range was 0.54 - egg to 0.99 - vegetable based diet

Recommended Intakes • RDA

– 0.8 g/kg/day for healthy adults

– 8-11% - of energy intake per day

– 50-65 grams of protein per day or between 200 to 250 Kcal.

– If junk food, sugar and fat is restricted, it is difficult not to get enough protein.

Proteins: Functions

• Formation cells: cytoplasm

• Formation essential biological compounds : Hb

• Regulation of fluids movement: osmotic pressure

• Regulation the acid-base balance: as buffers

• Supporting immune system: antibody

• Production of energy: 4 kcal

Fats Fats are groups of insoluble compounds and

include:

- Fatty acids

- Triglycerides (glycerol: sugar alcohol+3 fatty acids)

95% of dietary fat = energy and storage

- Phospholipids: one phosphat +2 fatty acids

( brain, hormones and corticosteroids…)

- Cholesterols: LDL and HDL

Cholesterols: LDL and HDL

cholesterol A waxy substance found in the blood and cells and needed for synthesis of cell membranes, vitamin D, and hormones.

• low-density lipoprotein (LDL) Blood fat that transports cholesterol to organs and tissues; excess amounts result in the accumulation of fatty deposits on artery walls.

• high-density lipoprotein (HDL) Blood fat that helps transport cholesterol out of the arteries, thereby protecting against heart disease.

Fatty Acids

---essential acids to be supplied in food

• Saturated (SFA) • Monounsaturated (MFA) • Polyunsaturated (PUFA) • Location of double bonds; how named:

– Omega-6 – Omega-3

• Essential fatty acids

Trans-Fatty Acids

Repeated heating UFA(plant)---TFA

• Trans versus cis format

• Sources of trans-fatty acids – Partially hydrogenated margarine, shortening,

commercial frying fat, high-fat baked goods, salty snacks

• Negative health effects: +LDL, -HDL, neonatal…

Lipids

• Functions

– Energy (9 kcal/g)

– Organ positioning, protection

– Fat-soluble vitamins and phytochemicals

Vitamins

• Vitamins are organic (carbon-containing) substances required in small amounts to regulate various processes within living cells

Humans need 13 vitamins; of these,

• four are fat-soluble (A, D, E, and K),

• and nine are water-soluble (C and the B-complex vitamins thiamin, ribofl avin, niacin, vitamin B-6, folate, vitamin B-12, biotin, and pantothenic acid).

Minerals—Inorganic Micronutrients

• Minerals are inorganic (non-carbon-containing) elements you need in relatively small amounts to help regulate body functions, aid in the growth and maintenance of body tissues, and help release energy

Water—Vital but Often Ignored

• Water is the major component in both foods and the human body: You are composed of about 50–60% water.

• You can live up to 50 days without food but only a few days without water.

Other Substances in Food • Antioxidants When the body uses oxygen or

breaks down certain fats or proteins as a normal part of metabolism, it gives rise to substances called free radicals

• free radical An electron-seeking compound that can react with fats, proteins, and DNA, damaging cell membranes and mutating genes in its search for electrons; produced through chemical reactions in the body and by exposure to environmental factors such as sunlight and tobacco smoke.

Daily exercise and weight control

Glycemic Index (GI)

• Is the blood glucose response to a given food, compared to standard food (glucose or white bread)

• Relative ability of different dietary carbohydrates to raise blood glucose levels

• Advantages of foods with low glycemic index (GI)

Glycaemic index

• Glycaemic index of a food is defined by the area under the two-hour blood glucose response curve (AUC) following the ingestion of a fixed portion of test carbohydrate (usually 50 g) as a proportion (%) of the AUC of the standard (either glucose or white bread)

The Glycemic Index

• The Glycemic Index measures the impact individual foods have on blood sugar levels.

• It ranks foods against white bread or glucose by potential to raise blood glucose levels.

Glycemic Index by the Numbers

• 55 or less A low glycemic index level.

• 56 to 69 A medium glycemic index level.

• 70 or more A high glycemic index level.

Low Glycemic Index • Low glycemic index, or so called good carbs,

are high in fiber and not overly processed. They're referred to as low glycemic index carbohydrates. The glucose from this type of carbohydrate is released at a slower rate. This means energy is released evenly over time, which keeps the body from experiencing an insulin spike.

Sources of low glycemic index foods: • Fruits • Vegetables • Whole grains • Legumes

High Glycemic Index • High glycemic index, or bad, carbs are those found in highly

processed foods (white breads, sugary drinks, and candy). • The glucose from these carbohydrates is quickly released and causes an

insulin spike. They're then removed from the bloodstream and transferred quickly into cells. When the sugar leaves the bloodstream, a person may experience a crash characterized by a low energy level.

• Sources of high glycemic index foods: • White bread • Pasta • Rice • Low-fiber cereals • Baked products • Bagels with honey • Crackers • Raisins • Bananas

Illness

Malnutrition

Example : Cancer

Altered

Food Intake

Altered

Digestion and

Absorption

Altered

Metabolism

Altered

Nutrient

Excretion

Examples: Loss

of appetite,

altered food

likes/dislikes,

difficulty chewing

and swallowing,

reduced saliva

secretion

Examples:

radiation enteritis,

surgical resection

of GI tract,

diarrhea

Example:

increased energy

needs due to

altered energy use

in cancer

Examples: fecal

loss of fat-soluble

vitamins and

calcium in clients

with cancers that

affect enzyme

secretion or bile

salt production

Antioxidants – an overview

• Antioxidants are molecules capable of reducing the causes or effects of oxidative stress

• Oxidative stress can be caused by environmental factors, disease, infection, inflammation, aging (ROS production) • ROS or “reactive oxygen species” include free radicals and other oxygenated molecules resulting from these factors • The body produces some endogenous antioxidants, but dietary antioxidants may provide additional line of defense • Flavonoids & other polyphenolics, Vitamins C & E, and carotenoids are the most common dietary antioxidants • Many herbs and botanicals also contain antioxidants

What do antioxidants do?

Prevent formation of ROS Inhibit xanthine oxidase, COX, LOX, GST monooxygenases,

chelate metals

Scavenge/remove ROS before they can damage important biomolecules

Aid the human body’s natural defenses Upregulate superoxide dismutase (O2

-.), catalase (H2O2), glutathione peroxidase (endogenous AO)

Repair oxidative damage Eliminate damaged molecules Prevent mutations