Topic A.1: Components of the Human Diet

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Topic A.1 Components of the Human Diet

• Page 208

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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
• So, we get these from foods

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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

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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

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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

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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)

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Kwashiorkor

• Symptoms include
• Fatigue, growth failure, loss of muscle mass
  edema, decreased immunity
• Complications
• Coma, shock, permanent mental and physical
  disability

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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

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A Place at the Table
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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

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PKU

• 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

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Solution

• 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)

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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

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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

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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

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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
• AVOID TRANS FATS!!

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Omega 3 Fatty Acids

• Example of cis fatty acids
• Healthy
• Good for your brain and heart
• Salmon, sardines,
• mackerel (fish)

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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

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Plaque

• 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)

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Heart Attacks Diet
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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

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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

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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

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Examples

• Minerals
• Sodium, calcium, iron
• Vitamins
• Vitamin A, C, D, ...
• Both are needed in very small amounts (were
  talking milligrams)
• Both prevent dificiency diseases

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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

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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)

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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)

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Dr. Oz Vitamin D
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Dietary Supplements

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

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Iodine

• 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

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Why dont 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

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Fiber

• 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.

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Take away message

• So what are some of the foods you should be
  eating? Why?
• What are foods you should avoid, or eat in
  moderation? Why?

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Take away message, from Dr. Oz