Topic a 1 components of the human diet
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Topic A.1: Components of the Human Diet. Page 208. Nutrients. Chemical substance found in foods and used in the human body Absorbed to give you energy, strengthen bones, prevent you from getting a disease (vitamins) Some amino acids and lipids can be synthesized by the body, many cannot

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  • Chemical substance found in foods and used in the human body

  • Absorbed to give you energy, strengthen bones, prevent you from getting a disease (vitamins)

  • Some amino acids and lipids can be synthesized by the body, many cannot

    • So, we get these from foods

Essential nutrients
Essential Nutrients

  • Nutrients obtained from foods because your body cannot synthesize them

  • Examples:

    • Essential amino acids

    • Essential fatty acids

    • Minerals

    • Most vitamins

    • Water

  • Carbohydrates are not essential nutrients b/c it is possible to live on diets with little to no carbohydrates

    • Not highly advised …

Amino acids
Amino Acids

  • 20 amino acids  proteins

  • Nine of these amino acids cannot be synthesized in the body

    • The human genome lacks the DNA sequence

    • Referred to as essential amino acids

  • The other 11 can be manufactured in the body; called nonessential amino acids

Protein deficiency
Protein Deficiency

  • Deficiency

    • A person is not getting enough of a certain nutrient

    • This causes a health problem

  • Protein deficiency

    • Can lead to insufficient production of blood plasma proteins

    • Retention of fluids in certain tissues

      • Notably the walls of the intestine

    • Example of malnutrition


  • Imbalance in the diet which leads to one or more diseases

    • Typically caused by a deficiency; in some circumstances, caused by an excess of one or more essential nutrients

  • Example: Kwashiorkor Disease

    • Common in children in non-industrialized countries

    • Name comes from Ghana

    • A second born child receives milk from his mother, but leaves little to no milk for the first born

    • First born may develop Kwashiorkor (protein deficiency)


  • Symptoms include:

    • Fatigue, growth failure, loss of muscle mass edema, decreased immunity

  • Complications:

    • Coma, shock, permanent mental and physical disability

A simple cure
A Simple Cure … ?

  • Eat more protein

  • However, sources of protein are expensive

    • Not an easy option for many families

  • Humanitarian efforts

    • High protein biscuits

    • Teach people how to raise chicken

    • Introduce eggs into diets

Turn and talk
Turn and Talk

  • To what degree do you think the following are factors in malnutrition?

    • Poverty and wealth

    • Cultural differences concerning dietary preference

    • Climatic conditions

    • Poor distribution of food (i.e. insufficient roads, bridges, railways)

    • A nomadic lifestyle

    • Corrupt politicians misusing agriculture or aid money

    • Lack of health care leading to a cycle of disease and poverty

Topic a 1 components of the human diet

  • Genetic disease caused by a mutated gene

  • The gene codes for a specific enzyme which converts the amino acid phenylalanine to tyrosine

  • People with PKU cannot convert phenylalanine into tyrosine, so they have very high levels of phenylalanine

    • This affects brain development

    • Untreated PKU  severe mental problems and learning difficulties


  • PKU can be diagnosed early with a blood test at birth

  • Parents can be informed what treatment if necessary

    • Common to follow a diet low in protein to avoid phenylalanine (eliminate milk, peanuts, cheese, meat)

    • Aspartame contains phenylalanine (one reason to label all food products)

Fatty acids
Fatty Acids

  • Not all fats are created equal

  • What is the same:

    • Carboxyl group (COOH)

    • Methyl group (CH3)

    • Hydrocarbon tail (in the middle)

  • See figures on pages 210-211

    • 7.1, 7.2, 7.3

Saturated fatty acids
Saturated Fatty Acids

  • Saturated with hydrogen atoms

  • No double bonds between the carbon groups

  • The shape is straight – no kinks

  • Animal products:

    • Bacon, butter, fat in red meat

    • Generally solid at room temperature

  • Eat in extreme moderation …

Monounsaturated fatty acids
Monounsaturated Fatty Acids

  • If one double bond exists in the chain of hydrocarbons, the fatty acid is NOT saturated

    • Monounsaturated fatty acids

  • Two or more double bonds …

    • Polyunsaturated fatty acids

    • Typically comes from plants

      • Olives, avocados, nuts

    • Tend to be liquid at room temperature

Cis vs trans fatty acids
Cis vs. Trans fatty acids

  • In some processed foods (snacks, cake), polyunsaturated fats are hydrogenated

  • This means the double bonds are eliminated by adding hydrogen atoms

    • Straightens out the natural bent shape

    • Naturally curved fatty acids are called cis

    • The hydrogenated fatty acids are called trans


Omega 3 fatty acids
Omega 3 Fatty Acids

  • Example of cis fatty acids

    • Healthy

    • Good for your brain and heart

    • Salmon, sardines,

      mackerel (fish)

Diets rich in fats
Diets rich in fats

  • The shape is important

  • Fatty acids that are curved are more easily picked up in the current of the blood stream

  • Straight fatty acids can lie flat against the walls

    • Deposits combine with cholesterol to form plaque

    • Inner lining of blood vessels


  • Reduces blood flow

  • A chunk may break off, get lodged, so no blood can pass through

  • If this happens in the heart (heart attack)

  • If this happens in the brain (stroke)

So about eating fats
So, about eating fats

  • A diet rich in saturated fats has a much higher chance of leading to serious cardiovascular problems later in life

  • Diets rich in polyunsaturated fats lead to lower quantities of plaque

    • Also tend to carry cholesterol away

  • Both types have high amounts of energy (CALORIES), so consuming a lot of either type is unhealthy

So take away message
So, take away message

  • When you eat, look at the food labels

  • Look for cholesterol, saturated fatty acids, polyunsaturated acids, and trans fat

  • Your body needs healthy fat to function, but focus on eating a balanced diet

  • Cardiovascular disease is also influenced by genetics, amount of exercise, and smoking

Vitamins and minerals
Vitamins and minerals

  • Often grouped together, but structurally very different

  • Minerals are inorganic

    • Does not contain carbon

    • Not synthesized by organisms

    • Rocks, soil, or sea water

  • Vitamins are organic

    • Synthesized in plants and animals

    • Contain carbon


  • Minerals:

    • Sodium, calcium, iron

  • Vitamins:

    • Vitamin A, C, D, ...

    • Both are needed in very small amounts (we’re talking milligrams)

    • Both prevent dificiency diseases

Vitamin c
Vitamin C

  • Recommended level 30-60 mg per day

    • Check your food labels

  • Vitamin C protects against infection, wound healing, and maintaining healthy gums, teeth, bones and blood vessels

    • Excess vitamin C can lead to kidney stones

    • Too little vitamin C can cause scurvy

      • Fluid retention, loss of teeth, bleeding into joints, and anemia

      • Untreated may be fatal

Vitamin d
Vitamin D

  • Formation of bones

  • Insufficient supply of vitamin D may cause rickets.

    • Deformities in the bones

    • Children with rickets do not reach optimal height; legs are often bowed inward or outward at the knees (see picture on page 216)

Vitamin d1
Vitamin D

  • Sources:

    • Exposure to sunlight

    • Food (fish: salmon, tuna, sardines; eggs, liver, milk and cereal are often fortified)

    • Vitamin supplements

  • Risks?

    • Exposure to sun  UV radiation (may cause sunburn and skin cancer called malignant melanoma)

Dietary supplements
Dietary Supplements

  • May be taken if the foods you eat do not provide you with vital minerals and nutrients


  • Iodine is a component of thyroxin, a hormone made by the thyroid gland

    • Regulates growth

  • Too little iodine  inflammation of the thyroid gland

    • This is called a goiter

    • Babies may suffer from growth and mental retardation

Why don t we see a lot of goiters in industrialized countries
Why don’t we see a lot of goiters in industrialized countries?

  • Iodine is added to salt

  • US; 1924

  • By the 1950s, goiters were essentially nonexistent in the US

Fiber countries?

  • “Roughage” – provides bulk

  • Cellulose in plant material

  • Reduces likelihood of constipation and chances of intestinal problems like colon cancer

  • Also links to reduced cardiovascular disease

    • Toxins bind to fiber and carried out of the body

  • Links to managing body mass  fiber helps you feel fuller longer

  • Many people do not get the amount of fiber they need on a daily basis.

Take away message
Take away message countries?

  • So what are some of the foods you should be eating? Why?

  • What are foods you should avoid, or eat in moderation? Why?