D1 Human nutrition Flashcards
What are nutrients?
Chemical substances found in foods that are ued in the human body
What are the 6 classes of nutrients?
- Carbohydrates
- Proteins
- Lipids
- vitamins
- minerals
- water
What are essential nutrients?
Nutrients that have to be ingested in the diet (only source is from food) as cannot be synthesized by the body.
* Cannot be synthesized in sufficient quantities
What are examples of essential nutrients?
- Some amino acids
- some unsaturated fatty acids
- some minerals
- calcium
- vitamins
- water
What are non-essential nutrients?
Nutrients that can be synthesised by the body or a suitable alternative can be used for the function
What are examples of non-essential nutrients?
Glucose, starch and other carbohydrates are non-essential, because they are used in respiration to provide energy and lipids can be used instead
What are some conditionally essential nutrients? Why?
In adults, Vitamin K is produced by the metabolism of symbiotic bacteria in the intestine.
But infants do nothave colonies of such bacteria at birth, they are ofen given a supplementary injection of vitamin K
What is vitamin C?
A compound called ascorbic acid
What is the use of ascorbic acid?
Syntehsis of collagen fibres that form part of many tissues in the body (i.e. skin and blood vessel walls)
What can synthesize vitamin C?
- Vast majority of plants and animals
- Inclluding most mammals
What leads to the inability to produce vitamin C?
Mutations in the GLO gene which codes for the production of the enzyme L-glulono-γ-lactone oxidase
What does the GLO gene code for?
the enzyme L-glulono-γ-lactone oxidase
What happened to teleost (a group of fish)?
They lost the ability to produce vitaminc C
What are examples of fishes from teleost that lost their ability to synthesize vitamin C?
Cod, salmon and herring
What mammals and primates can synthesize vitamin C?
Mammals: Dogs and cats
Primates: lorises and lemurs
What are 3 primates that cant synthesize vitamin C?
- humans
- chimpanzees
- apes
What is caused by a deficiency of vitamin C?
Scurvy
How are the symptoms of scurvy alleviated by?
by intake of dietary sources of the compound
What are the symptoms of scurvy?
- Skin discoloration & bruising
- Hemorrhaging
- Anaemia
- Dental issues
- Exhaustion/fatigue
- Sweeling of joints (edema)
Out of 20 amino acids in proteins, around how much are essential?
About half
What are essential amino acids?
Cannot be produced by the body and must be present in the diet
What are non-essential amino acids?
can be produced by the body and are therefore not required as part of the diet
What are conditionally non-essential amino acids?
Sometimes have to be ingested as the body does not have enough e.g. during pregnancy or early infancy
What are two examples of conditionally essential amino acids?
Threonine and arginine
How is threonine a conditionally essential amino acid?
Threonine is a essential amino acid that can be synthesized by the body if phenylalanine is present
What can be synthesized if phenylalanine is present?
Threonine amino acid
Why is arginine conditionally essential?
- Sufficient arginine can normally be produced by a healthy individual
- however the synthesis pathway is not active in prematurely born infants so they must obtain it through their diet
What does the “omega-3” and “omega-6” refer to?
Refers to the position of a double bond in relation to the end of the molecule
What are two (cis)-polyunsaturated fatty acids that are considered essential?
ALpha-linolenic acid (an omega-3 fatty acid) and linoleic acid (an omega-6 fatty acid)
What are alpha-linolenic acid and linoleic acid used for?
For the biosynthesis of a number of other compounds
* Large quantities involved in the development of the brain and the eye
Although alpha-linolenic acid and linoleic acid is used to develop the brain and eyes, what is there no evidence of in terms of taking its supplements?
There is little or no evidence that supplementation of a normal balanced diet with omega-3 fatty acids, for example from fish oils, enhances brain or eye development
Which foods are rich in essential fatty acids (omega-3 and omega-6)?
Fish, leafy vegetables, nuts, avocado
What does the lack of essential amino acids affect?
Production of proteins
* the body cannot make enough of the proteins that it needs
What is the condition when you lack essential amino acids?
Protein deficiency malnutrition
Why may essential amino acids be lacking?
- due to an overall insufficiency of protein in the diet
- or imbalance in the types of proteins
What can protein deficiency malnutrition cause? (3)
- Lack of blood plasma, which results in fluid being retained in tissues causing swelling (edema)
- Child development may be both mentally and physically retarded, with stunted growth and developmental disailities
- Adults may undergo serious weight loss (wasting)
How much minerals are needed in a diet?
Relatively small amounts
How can minerals be distingushed from vitamins?
By their chemical nature
What are minerals?
Chemical elements, usually in ionic form
e.g. calcium, magnesium, iron, phosphorus, sodium, potassium, iodine and chlorine
What is resulted when any mineral is lacking from the diet?
A deficiency disease results
What is an example of a mineral deficiency disease?
Mineral iodine
What is iodine needed for?
needed by the thyroid gland for synthesis of the hormone thyroxin
What does thyroxin hormone stimulate?
the metabolic rate and ensures that enough energy is released in the body.
What is deficiency disease is caused by the lack of iodine?
iodine dificiency disorder (IDD)
What happens if a pregnant woman has IDD?
Her baby may be born with permanenet brain damage
What happens to children who suffer from IDD after birth?
Their mental development and intelligence are impaired
How can IDD be cured?
By taking iodine supplementations
* adding the mineral to salt sold for human consumption for little cost
What deficiency disease is caused by the lack of calcium?
Rickets (as well as a lack of vitaminn D)
What deficiency disease is caused by the lack of iron?
Anaemia - lack of haemoglobin, less O2 transported around the body = light headed, pale, fatigue