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