Diet and Human Nutrition

Human Nutrition and Health Option A

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IB Bio Option A notes Human Nutrition and Health

[A1] Components of the human diet

Diet is the total food taken in by an individual. A balanced diet means that the diet provides food intake is equal to energy needs and to material needs (growth, tissue repair and metabolism-enzymes, hormones etc)


1 – 3 Nutrients are chemical substances, found in foods that are used in the human body.
Some nutrients are essential in the human diet, because foods are the only source of the nutrient.
Essential Nutrients
· some amino acids
· some unsaturated fats
· some minerals: ex calcium
· vitamins
· water

Other nutrients are non-essential, either because another nutrient can be used for the same purpose or they can be made in the body by another nutrient. Glucose, starch and other carbohydrates are non-essential because they are used in respiration to provide energy and lipids can be used instead. The carbon-hydrogen bonds found in carbohydrates and in fats contain the stored energy for respiration. In fact there are many more carbon-hydrogen bonds in fat and, therefore, they provide more energy per molecule than glucose. However, fats have important roles in cell membrane structure, insulation and energy storage and are used in respiration when glucose levels are low.
Glucose + oxygen forms carbon dioxide + water + energy (ATP and heat)

Fatty acid + oxygen forms carbon dioxide + water + energy (ATP and heat)

Of the 20 amino acids in proteins about half are essential because they cannot be synthesized in sufficient quantities, but the other half can be made from simpler nitrogen compounds. Foe example, phenylalanine is an essential amino acid, but tyrosine is non-essential because it can be synthesized from phenylalanine;

phenylalanine tyrosine hydroxylase tyrosine

Diet, disease and Nutritional practice
Diets deficient in nutrients can lead to disease


Disease OR
Nutrient(s) involved

Symptoms OR
Activity
Cause

Benefits
Kwashiorkor


Protein deficiency -
Shortage of one or
more essential
amino acids

· decrease in blood plasma proteins
· tissue fluid retention
· swelling of abdomen
· mental and physical retardation in developing children

Phenylketonuria
(PKU)

Lacks enzyme/tyrosine
hydroxylase

· genetic
· lacks enzyme to convert essential AA phenylalanine to tyrosine
· inc. phenylalanine causes brain damage
· since essential AA can be controlled by diet
Type II diabetes


Insulin ..


Scurvy


Low vitamin C in diet



Ricketts


Low vitamin D


Arteriolosclerosis
And coronary
heart
disease

High saturated fats
and cholesterol


Obesity


too much ..


Anorexia nervosa


too little .


Cretinism and
Goiter


Low Iodine ..


Lactose intolerance


Lacks enzyme/lactase


Breast feeding

Human milk vs artificial milk
Human milk lactose vs glucose
Human antibodies vs none
Human protein vs.
Human fatty acid vs.











6. Molecular structure of Fatty Acids – outline the VARIATION in molecular structure of fatty acids:
The elements of fatty acid structure are quite simple. There are two essential features:
1. A long hydrocarbon chain
The chain length ranges from 4 to 30 carbons; 12-24 is most common.
The chain is typically linear, and usually contains an even number of carbons.
2. A carboxylic acid group






Saturated fatty acids compared to unsaturated
















Cis and trans fatty acids:











7. Evaluate Health consequences:





































8. Distinguish between - Minerals are elements in ionic form and
Vitamins are organic compounds




DO the minerals we eat look like this?












Besides energy to keep these systems going we need food for their growth and tissue repair. We also need food for metabolism- the synthesis (anabolism) and break down (catabolism) of molecules.
Bodily Systems
Bodily Systems

Diet is the total food taken in by an individual. A balanced diet means that the diet provides food intake is equal to energy needs and to material needs (growth, tissue repair and metabolism-enzymes, hormones etc)

Constituents in a diet

Nutrients are chemical substances, found in foods that are used in the human body.
Some nutrients are essential in the human diet, because foods are the only source of the nutrient.
Essential Nutrients
· some amino acids
· some unsaturated fats
· some minerals: ex calcium
· vitamins
· water

Other nutrients are non-essential, either because another nutrient can be used for the same purpose or they can be made in the body by another nutrient. Glucose, starch and other carbohydrates are non-essential because they are used in respiration to provide energy and lipids can be used instead. The carbon-hydrogen bonds found in carbohydrates and in fats contain the stored energy for respiration. In fact there are many more carbon-hydrogen bonds in fat and, therefore, they provide more energy per molecule than glucose. However, fats have important roles in cell membrane structure, insulation and energy storage and are used in respiration when glucose levels are low.

Glucose + oxygen forms carbon dioxide + water + energy (ATP and heat)
Fatty acid + oxygen forms carbon dioxide + water + energy (ATP and heat)

Of the 20 amino acids in proteins about half are essential because they cannot be synthesized in sufficient quantities, but the other half can be made from simpler nitrogen compounds. For example, phenylalanine is an essential amino acid, but tyrosine is non-essential because it can be synthesized from phenylalanine;

phenylalanine tyrosine hydroxylase tyrosine
Diets deficient in either essential or non-essential nutrients can lead to disease. Non-essential nutrients may become essential if the diet has too low essential nutrients.

Check your syllabus for details:
Be able to describe the general structure and deficiency of the following:
Carbohydrates ( monosccharide such as glucose and fructose, disaccharide such as sucrose and lactose and polysaccharide such as plant starch and animal glycogen):
Lipid : saturated, unsaturated including trans fat :
Proteins; amino acid chains, enzymes etc
Minerals zinc, iodine, iron, phosphorous:
Vitamins A, B 12, C, D, E :
Water:
Fiber:
Although nucleic acids are an important biomolecule, they are not considered separately in diet and nutrition; for example, carbohydrates are a source of nucleic acid synthesis

Vitamins and Minerals:
Vitamins are organic substances that help maintain proper body activity and aid enzymes in catalyzed reactions. Many vitamins act as coenzymes. They are required in very small amounts.
Minerals are inorganic substances that enhance body functions and form important parts of the body.


DO the minerals we eat look like this?
Minerals of Canada Poster
Minerals of Canada Poster


The graph below looks less interesting but the minerals we eat do come from some beautiful crystals as seen above. The minerals we eat must be soluble in water; thus minerals such as sodium chloride, calcium carbonate or potassium chloride are the minerals in our diet, and they have been processed for easier intake. The metal is in ionic form (Na = Na+) and the nonmetal is as well (cl = cl-)

external image mineral-content.gif

Need for Balanced Diets

Recommended Daily Allowances (RDA): RDAs can to be used to assess whether a diet is adequate is essential nutrients (and energy). Diet can be adjusted accordingly.
RDA values allow consumer to more accurately assess food products and make more informed choices about their diet.
Nutritional facts labels can be used as a guide to determine if a particular food is a good source of specific nutrients or too high in unwanted ingredients, such as saturated fat, MSG or salt.


external image Disease1.gif

A Balanced Diet
leads to good health, whereas an unbalanced diet is poor nutrition (malnutrion) and may lead to poor health and disease.

Diet and Disease Presentations

Diet and disease
Present your topic with a power point and hand-out notes that

  • describe the disease and 3 symptoms
  • describe the biochemical nature of the nutrient involved - where relevant; state whether it is an essential or nonessential nutrient, the recommended amount in the diet, the amount needed (too little/too much) to prevent the disease, and the source of the nutrient
  • explain how this molecule functions in maintaining health
  • discuss the conditions that bring about a deficiency of the nutrient
  • outline a treatment process for the disease

Diseases

Disease
Nutrient(s) involved

Notes




Kwashiorkor


proteins


Phenylketonuria


enzyme/tyrosine
hydroxylase


Type II diabetes


insulin


Scurvy


vitamin C


Ricketts


vitamin D


Arteriolosclerosis and
coronary heart disease


some fats


Obesity


too much …


Anorexia nervosa


too little ….


Cretinism and Goiter


Iodine


Lactose intolerance


enzyme/lactase


Lactose intolerance


enzyme/lactase


Body mass index

If you are morbidly obese, you should remember three important points:
1. Morbid obesity does not mean weakness, laziness or gluttony. It is a serious medical condition with serious medical consequences. Current research suggests that many factors work together to influence your weight. These include genetics, your eating habits as a child and adult, hormones, and psychological and other factors.
2. You are not alone. About 65 percent of all Americans are considered overweight, about 25 percent are considered obese, and about 4 percent are considered morbidly obese. All of these numbers are on the rise.
3. There is hope. Resources are available to help you avoid the medical consequences of morbid obsity

How do I know if I'm morbidly obese?
A good way to assess your weight is to calculate your body mass index (BMI). Your BMI estimates how much you should weigh based on your height. You can check your BMI by consulting our BMI chart or by using the handy calculator below:


Enter your height:
feet inches

Enter your weight in pounds:
pounds

Your body mass index is:






health.howstuffworks.com/bmi.htm/printable



Vegan vs. vegeterian diets

external image protein.gif

external image VEGAN_DIET.jpg


external image images-image_popup-fn7_vegetarian.jpg

Vitamin and mineral deficiencies are unlikely in the vegeterian diet. However, Vegans may get insufficient cyanocobalamin (??); zinc (red meat, seafood and egg yolk but,also cereal and yeast); calciferol (milk eggs and liver, but also sunlight manufactures it from precursor molecules)

Lipids and Cholesterol


Choesterol is a lipid (insoluble in water). It is a steroid lipid, composed of 4 hydrocarbon rings
Cholesterol is carried in the blood by surrounding molecules called lippoproteins. Lippoproteins with a high % of protein are called high density (HDL) while lippooproteins with low % protein are called low density (LDL)

external image Cholesterol_Structure.jpg

Read how HDL and LDL cholestrol differs
http://www.cholesterol-and-health.com/cholesterol_structure.html


FUNCTIONS of cholesterol:
1.
Cholestrol is a precursor for some hormone metabolism, such as estrogen, progesterone and testosterone

external image ESTRAD~1.GIF



external image model.jpg


2.
Cholesterol is an important component of cell membranes

external image CellMembraneDrawing.jpg


SOURCES of cholesterol:
Cholesterol is synthsized by the liver, and brought into bloodstream by diet

external image 19269.jpg


EFFECTS of cholesterol

external image Cholesterol_CAPTIONED_COPYR.jpg


How it works:

external image hdl-image.jpg


DIETARY cholestrol
does not change the levels of cholestrol that much. Other dietary factors and genetic factors play a role in the levels of cholestrol. Normal levels of cholestrol range from 150 g/dL - 240g/dL
There is a positive correlation between the level of saturated fatty acids and blood cholesterol levels , and some unsaturated fats lower cholesterol levels. Thus, a diet with increased unstaurated fats and a decrease in polyunsaturated fats should lower cholesterol levels and, therefore, Coronary Heart Disease (CHD). However. since genetics also plays a role, in some families with diets of high saturated fat and low unsaturated fats, cholesterol levels are still low.
Also, positive correlations do not necessarily prove that cholestrol is the cause of CHD.
OBESITY , CHD and LIPIDS in the diet:

Obesity can occur when there are too many fats in the
diet because fats are high energy molecules. If the body does not use the energy, the fats are stored in fat cells.

external image 19267.jpg

CHD has a positive correlation to lipid intake. Saturated fats and cholestrol stick to arteial walls, causing plague build up. If the plague braks away fro the wall a blood clot forms. A blood clot in the coronary vessels prevent blodd, thus oxygen, from getting to cardiac cells. There is little energy for the heart to contract. This causes a heart attack.
Also, the coronary arteries can build up plaque so that the lumen becomes too narrow for blood to pass through; again preventing oxygen from getting to the heart contracting cells.




external image reduced%20cholesterol.jpg
external image ei_0028.gif
Remember:
Data showing a positive correlation is not proof of anything.
Also, some countries have low CHD despite high lipid intake
Some families have low CHD despite high lipid diets, possibly due to genetic factors
Smoking and high blood pressure are also risk factors for CHD
There are dirrerent types of fattty acids and cholesterol, which have different effects.


Chemical additives

Uses: preservatives, antioxidants, coloring, flavoring, stabilizers, acid -regulators

external image onion_imagearticle1214.jpg

Nitrites
Sodium nitrite (or sodium nitrate) is used as a preservative, coloring and flavoring in bacon, ham, hot dogs, luncheon meats, corned beef, smoked fish and other processed meats. These additives can lead to the formation of cancer-causing chemicals called nitrosamines.
Some studies have found a link between consuming cured meats and nitrite and cancer in humans
Red 3
This food coloring is used in cherries (in fruit cocktails), baked goods and candy. It causes thyroid tumors in rats, and may cause them in humans as well.
Yellow 6 (tartrazine)
As the third most often used food coloring, yellow 6 is found in many products, including backed goods, candy, gelatin and sausages. It has been found to cause adrenal gland and kidney tumors, and contains small amounts of many carcinogens
Monosodium glutamate (MSG)
MSG is used as a flavor enhancer in many packaged foods, including soups, salad dressings, sausages, hot dogs, canned tuna, potato chips and many more. According to Dr. Russell Blaylock, an author and neurosurgeon, there is a link between sudden cardiac death, particularly in athletes, and excitotoxic damage caused by food additives like MSG and artificial sweeteners. Excitotoxins are, according to Dr. Blaylock, "A group of excitatory amino acids that can cause sensitive neurons to die."


Discuss Nutrition and rickets, anemia and osteoporosis:
Example:

Rickets is the result of poor bone growth.
Most cases of rickets are caused by a lack of nutritent vitamin D (calciferol), but rickets can also be inherited. Calcium deficiency, or poor calcium absorption, can also lead to rickets. Vitamin D helps the bones absorb calcium and phosphorus from food. When people do not get enough vitamin D, his or her bones do not get those necessary nutrients that makes bones strong. However, fish oils are a good source of Vit D and exposure to sufficient UV sunlight helps synthesize vit D from pro-vitamins in the skin. Pro-vitamins for vitamin D can be obtained from green vegetables.

Children ages 6-24 months are at the highest risk of rickets because their bones are growing very rapidly during this period. A child may also be at risk if he or she:

  • Has dark skin
  • Doesn't get moderate exposure to sunlight
  • Wears sunscreen at all times when outside
  • Doesn't eat foods containing vitamin D
  • Breastfeeds without a vitamin D supplements

What are the symptoms of rickets?

The image below shows what some of the symptoms of rickets look like.
Child with rickets
Child with rickets
Osteoporosis:
external image osteoporosis.jpg


While fish oils are a good source of vitamin D, green leafy vegetables, such as spinach, are a good source of calcium and pro-vitamin D. However, other factors play a role in osteoporosis. Low estrogen levels, lack of physical exercise and long treatments with steroid drugs can play a large role in the development of osteoporosis.
external image spinach_nutrition.jpg
Spinach nutrition label - shows nutrients (helpful) but not pro-vitamins (unhelpful)

3.11 Global malnutrition

external image 25743501.jpg


Condtitions in a country that can cause malnutrition
Economics:
unequal distribution of wealth
insufficient resources to import food
insufficient resources to produce food
no money to distribute food
corruption
economic sanctions
poverty leads to lack of education

Environmental change, such as, drought or floods causing a loss of crops, can lead to the conditions listed above.
Social situations such as corruption, wars or population increases can lead to decreased money, crop production and unequal ditribution.
Cultural practices; cultures may have a deficiency inherent in the diet may lack another important nutrient; for example, a diet mainly of maize may suffer from a lack B3
Hygiene
Food poisoning
occurs when bacteria such as Salmonella grow on the food. In the intestine the Salmonella releases toxins that makes you sick.
wash hands before touching food
cooked and uncooked food stored separately
frozen food should be completely thawed before cooking
eat food before 'use' date
flies and other animals should be kept from contaminating food
foods that mey contain food poisoning bacteria should be cooked throughly

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INVESTIGATION How close are my daily food servings to the recommended food servings of the USDA?
1. Organize a table so that you can record the number of servings of each food group over 5 days. Use the food groups of the new food pyramid. A serving is approximately the size of a clenched fist.
2. Average your food servings intake.
3. Draw a bar chart with number of food servings per day on the y axis and the food types on the x axis.
4. Convert your food servings on to a food pyramid
5. Compare your pyramid to the recommended food pyramid
6. Evaluate your diet for a) small child b) a teenager c) a non-pregant woman compared to a lactating woman and d) elderly person
7. Evaluate this investigation for determing whether you are getting your recommended dietary allowance (RDA)