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Option A – Human Nutrition And Health Outline

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IB Biology SL 1 Option A - Human Nutrition and Health

Option A - Human Nutrition and Health Independent Learning Assignment

A.1: Components of the Human Diet A.1.1 Define nutrient Nutrient: Nutrients are chemical substances that are found in food and are used in the body.

A.1.2 List the types of nutrients that are essential in the human diet

1. Water

2. Several Fatty Acids (omega-3 and omega-6)

3. Minerals (iron, potassium, sodium, calcium, phosphorous, and iodine)

4. Amino acids (phenylalanine and methionine)

5. Vitamins (Vitamins A, C, D and folate)

A.1.3 State that non-essential amino acids can be synthesized in the body from other nutrients Non-essential amino acids can be replaced or synthesized by the body from other nutrients through the use of enzymes; therefore it is not necessary for out diet. Examples include:
 Carbohydrates/Sugars (energy can come from fats or proteins)
 Other minerals and some vitamins
 Saturated fatty acids
 Some amino acids.

A.1.4 Outline the consequences of Protein Deficiency Malnutrition Protein Deficiency Malnutrition is caused by the lack of essential acids due to the low protein intake.
 Due to this, there is a lack of plasma proteins in the blood, which leads to the retention of fluid in the tissues, thus the symptom of abdominal bloating is seen. Edema
 Another consequence that can be seen is the wasting of muscles, flaky appearance of the skin and sparse hair with a lack of pigmentation.
 If it is seen in the development of children, then it can cause retardation in the physical and mental development of the child.
 Those who suffer with PDM, will present lethargic symptoms (lack of energy and enthusiasm)
 Immune system impairment.

A.1.5 Explain the causes and consequences of phenylketonuria (PKU) and how early diagnosis and a special diet can reduce the consequences

IB Biology SL 3 Option A - Human Nutrition and Health What causes phenylketonuria?
Autosomal recessive, disease-causing alleles missense basesubstitution mutation on the gene for the enzyme phenylalanine hydroxylase. What are the consequences on the Human Body?
Phenylalaline cannot be metabolized into tyrosine. The Phenylalaline builds up in the brain, and competes with amino-acids related to transport. This causes Brain Damage and Mental Retardation (symptoms = tremors, seizures, eczema, skin rashes) How to detect it?
 Can be diagnosed simply with a blood test for the levels of phenylalaline (conducted after birth) What is the cure?
 A strict low-Phenylalaline diet: no dairy, meat, breastmilk, nuts, or aspartame (artificial sweetener) and medicine.

A.1.6 Outline the variation in the molecular structure of fatty acids, cis- and trans- unsaturated fatty acids, monounsaturated and polyunsaturated fatty acids

Fatty acids all have the same general structure, but have variation in the bonding between the carbon atoms. o Saturated fatty acids have no double bonds between carbon atoms

o Monounsaturated fatty acids have a single double bond between two carbon atoms o Polyunsaturated fatty acids have multiple double bonds between carbon atoms o In cis isomers, hydrogen atoms attached to the doublebonded carbon atoms are on the same side. o In trans isomers, hydrogen atoms attached to the double-bonded carbon atoms are on different sides.

IB Biology SL 5 Option A - Human Nutrition and Health

A.1.7 Evaluate the health consequences of diets rich in the various types of fatty acid In order to understand this it is necessary to look at the Population studies (Cohort studies / which can show correlation, but not attribute cause) or Random Controlled Trials (clinical studies /
which can attribute correlation and maybe cause). Nevertheless, there is variation within all populations and genetic factors may also play a role. Fatty Acid Omega-3

Trans Fats

Saturated Fats

Sources &
Examples Fish, nuts &
veg. oils

Possible Effects


Reduced blood pressure and triglycerides

Good Clinical Evidence

Inult tribes eat loads of fish Reduce blood clotting and reduce risk of heart rates and strokes

Good cohort study evidence, some evidence from clinical trials

Partially Hydrogenated veg. oils and margarines, deep fried foods - junk food or convenience food diet Meat, seafood, fullcream milk and dairy, cheese, palm oil, coconut oil

Reduces helpful cholesterol (HDL) and increases harmful cholesterol (LDL). Increased blood pressure, risks of CHD, heart attack and stroke.

Strong clinical and epidemiological evidence (correlation with disease)

Increases LDL, and can lead to atherosclerosis, CHD, stroke and heart attacks

Strong clinical and epidemiological evidence (correlation with disease)

A.1.8 Distinguish between vitamins and minerals in terms of their chemical structure Minerals: Inorganic elements in ionic form (found in food) - (Sodium, Potassium) Vitamins: Organic compounds (made by plants or animals), some can be made in our body, others need to be in our diet - (Retinol /
Vitamin A, Calciferol / Vit. D)

A.1.9 Outline two of the methods that have been used to determine the recommended daily intake of vitamin C Vitamin C: Produces Collagen, maintains mucus membranes, promotes healing and skin growth. Retrospective Research:
 A traditional method that was used to identify sufferers of vitamin C diseases (e.g. scurvy) and determine their levels of vitamin C.
 Resulted in an inexact method for determining dietary requirements since its primary function was to prevent disease, not promoting cellular functions Clinical Trials:
 Recent attempts at determining the recommended daily intake of vitamin have involved undertaking experimental studies.
 Resulted in testing cell cultures, guinea pigs and finally humans.
 The purposes of these tests are to identify cellular function and disease onset at different daily dosages of vitamin C.

A.1.10 Discuss the amount of Vitamin C that an adult should consume per day, including the level needed to prevent scurvy, claims that higher intakes protect against upper respiratory tract infections, and danger of rebound malnutrition The RDI for vitamin C (ascorbic acid) is set at 45-60mg per day. Mega-doses of vitamin C can prevent infections of the respiratory tract and speed healing and recovery (1000mg-3000mg /day) However, mega-doses (over 100mg vitamin C per day) can cause the risk of rebound malnutrition. The human body is effective and regulating itself internally though negative feedback mechanisms.

A.1.11 List the sources of vitamin D in human diets Vitamin D can be produced by the skin in response to sunlight, but can also be sourced in a diet containing:
 Cereal (fortified)
 Oily fish (e.g. tuna)
 Milk (fortified)

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