Topic A.1: Components of the Human Diet

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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

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

• 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

• 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

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)

Kwashiorkor

• Symptoms include: – Fatigue, growth failure,

loss of muscle mass edema, decreased immunity

• Complications: – Coma, shock,

permanent mental and physical disability

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

A Place at the Table

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

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

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)

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 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

• 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

• 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!!

Omega 3 Fatty Acids

• Example of cis fatty acids – Healthy– Good for your brain and heart– Salmon, sardines,

mackerel (fish)

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

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)

Heart Attacks & Diet

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

• 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

• 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

Examples

• 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

• 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

• 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 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)

Dr. Oz & Vitamin D

Dietary Supplements

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

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

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

• “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

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

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

Take away message, from Dr. Oz