Transcript Nutrition01_Intro

Nutrition
Western Perspective
Nutrients
• A nutrient is any substance the body can use
to obtain energy, synthesize tissues, or
regulate functions.
• Nutrients provide the fuel to do physical work
and perform metabolic functions.
• Nutrients are necessary for normal growth
and development.
Nutrients
• Nutrients regulate hundreds of thousands of
body processes.
• Essential nutrients are substances that must
be obtained from the diet because the body
cannot make it or because the body cannot
make adequate amounts of it.
• The minimum diet for human growth and
development must supply about 45 essential
nutrients.
Classes of Nutrients
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Carbohydrates
Lipids (fats and oils)
Proteins
Vitamins
Minerals
Water
Nutrients
• To define a nutrient we focus on what
happens in its absence.
• A deficiency of a nutrient will cause an
adverse change in health.
Nutrients
• Replacing the deficient nutrient should restore
health if the nutrient is supplied before
permanent damage is done.
• Other substances in food (i.e. caffeine,
phytochemicals, and fiber) affect our health,
but do not fit the classical definition of a
nutrient.
Functions of Nutrients
• Provide fuel or energy
• Regulate body processes
• Contribute to body structures
Nutrient Function
• Virtually all nutrients regulate body processes
and contribute to body structures.
• Only the nutrients protein, carbohydrate, and
fat are sources of energy.
Micro vs. Macro Nutrients
• The body needs large quantities of
carbohydrate, protein, and fat; therefore,
these are called macronutrients.
• The body needs much smaller quantities of
vitamins and minerals; therefore, these are
called micronutrients.
Organic vs. Inorganic
• Carbohydrates, lipids, proteins, and vitamins
are all organic.
• Minerals and water are inorganic.
• The inorganic nutrients are simpler structures.
Water is a very simple structure. Minerals are
single elements, although they are often
consumed as part of larger compounds.
Organic vs. Inorganic
• Organic nutrients have more complex
structures.
• Carbohydrates, lipids, and proteins are broken
down into simpler building blocks before they
are absorbed in the small intestines.
• Vitamins are elaborately structured
compounds.
Nutrients in Food
• It is rare for a food to contain just one
nutrient.
• Foods contain mixtures of nutrients.
• Typically, one nutrient such as protein,
carbohydrate, or fat will be predominant in
the food.
Carbohydrates
• Carbohydrates are a large group of
compounds, including sugars, starches, and
dietary fibers.
• Carbohydrate literally means “hydrate of
carbon”.
• Carbohydrates are made of carbon, hydrogen,
and oxygen.
• They are a major source of fuel for the body.
Dietary Sources of Carbohydrates
• Carbohydrates are the starches and sugars
found in grains, vegetables, legumes (dry
beans and peas), and fruits.
• Dairy products have some carbohydrates, but
there are practically none in meats.
Glucose
• Ingested carbohydrates are converted into
glucose in the gastrointestinal system.
• Glucose is a simple sugar compound.
• Glucose is found in the blood and serves as a
primary source of energy for cells and tissues.
Lipids
• Lipids are fats and oils.
• Fat-like substances such as cholesterol and
phospholipids also fall into this category.
• Lipids, like carbohydrates, contain carbon,
hydrogen, and oxygen.
Lipid Uses
• Triglycerides (fats) are also a major fuel source
for the body.
• Triglycerides, cholesterol, and phospholipids
provide structure for body cells, carry fat
soluble vitamins (A,D,E, and K), and
cholesterol is a building block for many
hormones.
Dietary Sources of Lipids
• Lipids are obtained through the fats and oils
we use to cook foods.
• Lipids are naturally occurring in meat and
dairy products.
• Plant sources of lipids include coconut, olives,
and avocado.
Proteins
• Proteins are organic compounds consisting of
smaller building blocks called amino acids.
• In addition to carbon, hydrogen, and oxygen,
proteins contain nitrogen.
• The amino acids that we obtain from dietary
protein combine with the amino acids made in
the body to make hundreds of different
proteins.
Function of Proteins
• Proteins are utilized to build and maintain
body structure.
• Proteins can be used for energy.
• Enzymes are protein structures that regulate
chemical reactions in the body.
Dietary Sources of Proteins
• Meat and diary products are the most
concentrated sources of protein.
• Grains, legumes, and vegetables all contribute
protein to the diet.
• Fruits contribute negligible amounts of
protein.
Vitamins
• Vitamins are organic compounds necessary
for promotion of reproduction, growth, and
maintenance of the body.
• Vitamins are required in miniscule amounts.
• Vitamins are not broken down for energy;
however, they do help to extract energy from
carbohydrates, proteins, and fats.
Fat Soluble Vitamins
• Vitamins A, D, E, and K are the fat soluble
vitamins.
• Fat-soluble vitamins are stored in larger
quantities in the body than the water soluble
vitamins.
• Fat soluble vitamins can be toxic in high doses.
Water Soluble Vitamins
• The water soluble vitamins include vitamin C,
and eight B vitamins: thiamin (B1), riboflavin
(B2), niacin (B3), pyridoxine (B6), cobalamin
(B12), folate, pantothenic acid, and biotin.
• Water soluble vitamins are much less likely to
produce toxicity; however, pyridoxine and
niacin can in very high doses.
Dietary Sources of Vitamins
• Vitamins are abundant in fruits and
vegetables, but they are also found in meats,
grains, legumes, dairy products, and fats.
• A well balanced diet can provide the
necessary nutrients and eliminate the need
for supplementation.
Minerals
• Minerals are simple, inorganic substances
needed for growth and regulation of body
processes.
• At least 16 minerals are known to be essential
to health.
Minerals
• Some of the more prominent minerals are
sodium, chloride, potassium, calcium,
phosphorous, magnesium, and sulfur. These
minerals are needed in relatively large quantities
and are referred to as macrominerals.
• The other minerals are needed in very small
amounts and are referred to as microminerals or
trace minerals.
• Iron, zinc, copper, manganese, molybdenum,
selenium, iodine, and fluoride are trace minerals.
Functions of Minerals
• Minerals can be found in structural roles (i.e.
calcium, phosphorous, and fluoride in bones
and teeth.
• Minerals have regulatory roles such as muscle
contraction and fluid balance.
Dietary Sources of Minerals
• Minerals are abundant in both plant and
animal sources.
• Mineral deficiency is uncommon, except for
calcium and iron deficiency.
Water
• Water is the most important nutrient.
• Water is one of the simplest nutrients.
• The human body is nearly 60% water.
Water
• Most food products contain water.
• Fruits and vegetables are especially high in
water.
• Water helps to regulate body temperature,
lubricate the joints, transport nutrients,
transport wastes, etc.
Nutrients and Energy
• One of the primary reasons we eat food is to
obtain energy.
• Carbohydrates, lipids (triglycerides only), and
proteins are the nutrient sources that provide
energy.
• Alcohol can also be used as an energy source.
Calories
• In nutrition, we speak of the potential energy
stored in foods in terms of heat units called
kilocalories (1,000 calories).
Calories
• One kilocalorie (kcal) is the amount of energy
(heat) required to raise the temperature of 1
kilogram (kg) of water by 1⁰ Celsius.
• Calorie is the general term for energy in food
and used synonymously with the term energy.
It is often used instead of kilocalorie on food
labels, in diet books, etc.
Energy in Various Foods
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Carbohydrate
Protein
Alcohol
Fat
4kcal of energy per gram.
4kcal of energy per gram.
7kcal of energy per gram.
9kcal of energy per gram.
Calculate the Total Energy in kcal
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Bagel plus 1.5 ounces of cream cheese
39 grams of carbohydrate
10 grams of protein
16 grams of fat
Percentages of Calories in Food
• Current health recommendations suggest
limiting fat intake to no more than 30% of
total caloric intake for the day.
Phytochemicals
• Phytochemicals are substances in plants that
may possess health-protective effects, even
though they are not essential for life.
• Thousands of componds, pigments, and
natural anti-oxidants have been identified in
plants.
Phytochemicals
• Phytochemicals have been shown to protect
against heart disease, hypertension, cancer,
and diabetes among other things.
• Phytochemicals modify hormone effects and
neutralize free radicals, which helps protect
against cancer.