Human nutrition
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Human Nutrition. (Cambridge Biology Chapter 4). First of all…. Why do we need to eat? Why do we need to eat a balanced diet?. Nutrition is:. From Latin: “nutrire” = “nourishing”

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Human Nutrition

(Cambridge Biology Chapter 4)


First of all…

  • Why do we need to eat?

  • Why do we need to eat a balanced diet?


Nutrition is:

  • From Latin: “nutrire” = “nourishing”

  • Obtaining organic substances and mineral ions from which organisms obtain their energy and raw materials for growth and tissue repair.


6 Types of Nutrients

  • Carbohydrates

  • Proteins

  • Fats

  • Vitamins

  • Inorganic Ions (“Minerals”)

  • Water


Organic vs. Inorganic Nutrients

Organic

Inorganic

No Carbon

Typically “stand-alone” substances.

For example: Salt (mineral of NaCl)

  • Molecules contain Carbon

  • Typically components of plant or animal tissues.

  • For example: Pepper (ground plant fruits)


Organic or Inorganic?

  • Sugar

  • Iron

  • Wood

  • Water

  • Oxygen

  • Alcohol

  • O

  • I

  • O

  • I

  • I

  • O


Why Do Humans Need Nutrients?

  • To give us ENERGY!

    • We need energy for heat, movement, and chemical reactions in our bodies.

    • Carbs + Fats.

  • To give us Building Materials:

    • We need to build the cells in our bodies.

    • Proteins.


Why Else?

  • To give us Chemicals for Reactions

    • We need chemicals to make chemical reactions take place in our bodies.

    • Proteins, vitamins, minerals, and water.


Carbohydrates

  • Carbo = carbon

  • Hydrate = water = hydrogen and oxygen

  • So “carbs” are molecules of C, H, and O.


I bet you can do this…

  • What’s a saccharide?

  • A monosaccharide?

  • A disaccharide?

  • A polysaccharide?

  • “sugar”

  • “one sugar”

  • “two sugars”

  • “many sugars”


Simple Sugars: Monosaccharides

  • A single ring of C, O, and H.

  • Glucose (yum!) 

  • Fructose

  • Galactose


Complex Sugars: Disaccharides

  • Two sugar rings linked together.

  • Glucose +

  • Galactose =

  • Lactose


Complex Sugars: Polysaccharides

  • 3 Types:

    • Cellulose

      • Makes up plant cell walls

    • Starch

      • Stored as food reserve in plant cells

    • Glycogen

      • Stored as food reserve in animal liver and muscle cells


Cellulose


Starch


Glycogen (in liver cells)


Why do we need Carbs?

  • One reason: Energy!

  • Plants take energy from the Sun, and turn it into carbohydrates.

  • Animals eat plants and use the energy to do work (survive).

  • Extra carbohydrates are changed into Fat.


What is a Low-Carb Diet?

  • Low-carbohydrate diets restrict caloric intake by reducing the consumption of carbohydrates to 20 to 60 g per day (typically less than 20 percent of the daily caloric intake). The consumption of protein and fat is increased to compensate for part of the calories that formerly came from carbohydrates.

  • … but what are calories?


Calories

  • Energy in food is measured in Calories.

  • Average need is 2,000 calories per day.

  • Carbs have lots of energy (lots of calories).

  • Going on a low-carb diet means you get less energy out of your food.

  • Is that a good idea?


Proteins

  • A long molecule made of smaller molecules called amino acids.


Amino Acids

  • There are only 20 different amino acids.

  • They can be linked in any order.

  • A protein’s “identity” is based on the number and order of amino acids.


Amino Acids


Protein Chains


Protein Molecules


Where Do We Get Proteins?

  • We make them from amino acids.

  • When we eat proteins, the molecules are chopped up into amino acids.

  • Then we put them back together to make the proteins we need.


Sources of Proteins


Why Do We Need Proteins?

  • Building Blocks for our cells:

    • Cell membranes

    • Muscle: for cells to produce movement

    • Bones/Skin: Collagen

    • Hair/Nails: Keratin


Keratin


Proteins are also…

  • Enzymes!(remember those?)

    • Help chemical reactions take place

  • Hemoglobin

    • Red stuff in our blood; carries Oxygen

  • Antibodies

    • Attack bacteria and viruses

  • Hormones – like Insulin

  • Energy – but not usually


Hemoglobin


Amino Acids in Food

  • Nonessential AA’s

    • Our body can make them on its own.

  • Essential AA’s

    • Body can’t make them; they must come from foods we eat.

    • Meat, milk, and eggs contain all the essential amino acids we need.

    • Fruit, grains, and vegetables contain only some.


What about Vegetarians?

  • They just have to make sure they get all the essential amino acids from a diet that includes a lot different kinds of foods, especially grains and legumes (beans, etc.)


Fat

  • One Fat molecule is made of:

    • 1 molecule of Glycerol

    • 3 fatty acids


Sources of Fat

From Animals

From Plants

Peanut Oil

Olive Oil

Corn/ Vegetable Oil

Unsaturated Fats

  • Lard (pig fat)

  • Fish Oil

  • Butter (from milk)

  • Saturated Fats


Saturated vs. Unsaturated Fats


Why Do We Need Fats?

  • Energy!

    • We can use it or store it.

    • Fat contains more energy than carbohydrates.

    • 1 gram of Fat = 2x the energy in 1 gram of Carbs

  • Cell Membranes

  • Heat Insulation


Fat as Insulation


Vitamins

  • Organic substances that we only need in very small amounts in our diet.


Vitamin C


Vitamin C

  • Helps make the protein Collagen.

  • Collagen is part of bones, skin, and blood vessels.

  • Without Vitamin C, skin and blood vessels become weak due to lack of Collagen.

  • Without enough Vitamin C, you can get a disease called Scurvy!

    • Bruises and ulcers on skin; weak gums


Scurvy


Vitamin D


Vitamin D

  • Helps us absorb Calcium from food to make bones and teeth.

  • We can eat it from both plants and animals.

  • We can also make it when we get enough sunshine.

  • Without enough Vitamin D, you can get a disease called Rickets!

    • Bone is soft and grows into bent shapes


Rickets


Vitamin A

  • Helps with a LOT of functions in the body.

  • Without enough Vitamin A, impaired vision or blindness can occur.


Vitamin A


Inorganic Ions

  • Sometimes called Minerals.

  • We only need them in small amounts.


Iron

  • Helps us make Hemoglobin.

  • Makes our blood red!

  • Carries Oxygen in our blood.

  • Without enough Iron, you can get a disease called Anemia!

    • Feel tired very easily


Iron in Blood


Calcium

  • Our bones and teeth are made of calcium salts.

  • Without enough calcium…?

  • Need Vitamin D to absorb it.


Calcium


Sources of Calcium


So… Why do we need a Balanced Diet?


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