Nutrition Flashcards
What is nutrition?
Nutrition is the utilization of food stuffs by living organisms. Most of the major biomolecules that are metabolized in the body come from the food that we eat.
The body is however able to synthesize some of the biomolecules
List the essential amino acids
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1. Phenylalanine ,
2. valine,
3. threonine.
4. Isoleucine,
5. methionine,
6. histidine,
7. arginine,
8. leucine
9. Tryptophan
10. lysine
List the non-essential amino acids
alanine,
aspartate,
serine,
glycine,
tyrosine
Arginine
Cysteine
Glutamate
Glutamine
Proline
Which food groups make up macronutrients?
i) carbohydrates
ii) lipids
iii) proteins
Differentiate between under nutrition and over consumption
Under nutrition is the problem of the developing countries which is associated with diseases such as kwashiorkor, marasmus and diseases due to deficiency of vitamins and minerals.
Excess consumption is a problem of the developed countries and causes overweight and obesity leading to cardiovascular diseases, diabetes and some cancers
Explain the caloric value of food
Food stuffs produce different amounts of energy which can be measured in the lab in a bomb calorimeter and the unit of energy is calories whose symbol is small c.
In biological systems, the unit of energy is Kilo calories(1000 calories).
Below is the amount of energy produced from the various food stuffs:
1. carbohydrates: 4 Kcalories per gram.
2. Proteins: 4 Kcalories per gram.
3. Lipids: 9 Kcalories per gram.
Sources of the energy daily requirements:
- 45 to 55% comes from carbohydrates.
- 25 to 30% comes from lipids.
- 15 to 20% comes from proteins
Define the Basal Metabolic rate
This is the energy output required at rest but not during asleep.
It is measured under controlled conditions 12hrs after the last meal.
It is the energy required to maintain respiration, circulation, muscle tone, functioning of the visceral such as kidneys, liver and brain.
Describe the total daily energy requirements.
The total Energy requirements is determined by measuring heat output from the body.
It is estimated indirectly from the consumption of oxygen by measuring the respiratory quotient.
The respiratory quotient is the ratio of the volume of carbon dioxide produced and the volume of oxygen consumed.
Total Daily Energy Requirements is the sum of the Basal Metabolic Rate plus the energy required for physical activity plus the energy required for synthesizing reserves during the fed state called the Specific dynamic action (SDA)
Describe the digestion and absorption of carbohydrates
Digestion of starch starts in the mouth. The food is broken in small particles and it is acted upon by the salivary amylase in the mouth that breaks the alpha type of glycosidic bonds. The pH in the mouth is alkaline.
In the stomach the acidic environment with the pH of around 2 stops the action of the salivary amylase.
When the food goes down to the duodenum, the carbohydrates are acted upon by the pancreatic amylase produced from the pancreas at a pH of around 8.6
In the jejumun, there are enzymes lactase, sucrase and maltase that breakdown of lactose, sucrose and maltose respectively.
Absorption of the monosaccharides in the ileum is through active transportation against the concentration gradient coupled to the sodium and potassium pump
Describe the biological value of proteins
The biological value of proteins is based on the amino acid composition and the digestibility. And based on the biological value , the proteins are divided in 3 groups:
1. Proteins of high biological value – These contain all the essential amino acids and are easily digestable. They include eggs and milk protein( lactalbumin)
2. Proteins of good biological value – These contain all the essential amino acids but they are not so easily digestable. They include muscle meat, fish, poutry, organ meat and soya beans
3. Proteins of poor biological value – These lack some essential amino acids and are not easily digestable. These are proteins from vegetable sources like cereals and legumes. Proteins in beans lack the essential amino acid methionine while the protein zein in maize lacks the essential amino acid tryptophan
Explain the concept of the amino acid pool
Unlike carbohydrates and fats there is no physical storage form of amino acids.
There is a continuous break down of old proteins which are replaced by the synthesis of new proteins.
The amino acids that are available in the body constitute the Amino acid pool which have got 2 sources: i.)Exogenous from the diet, ii.) Endogenous from the break down of the old body(tissue) proteins.
The amino acid in the amino acid pool are utilized for i.) the synthesis of new body proteins, ii) synthesis of nitrogenous compounds e.g. heme, purines and pyrimidines, amines
Describe the effects of protein energy malnutrition
This is due undernutrition and is brought about by the deficiency of both proteins and the food that provide the energy: the carbohydrates and lipids.
There are 2 forms of forms of PEM namely, marasmus and kwashiorkor.
List and explain the factors that affect the BMR
The following are some factors that affect the BMR:
- Body weight: BMR increases with weight, the greater the active tissue in a large body the higher th BMR.
- Age: BMR reduces with age because the muscle which is active has been replaced by adipose tissue which is metabolically less active. It is higher in children than in adults.
- Gender: the BMR is high in males than females because females have more fat which is metabolically less active.
Explain carbohydrates as a daily energy requirement
About 45 to 55 % of the Daily Energy Requirements should come from carbohydrates.
A 70Kg man requires about 3000 Kcalories of energy per day and most of it comes from carbohydrates.
This is mainly in the form of starch and the disaccharides sucrose and lactose. Cellulose is also an important part of the diet and it provides roughage.
Adequate amounts of carbohydrates in the diet have a protein sparing action because it reduces the need to synthesis glucose in gluconeogenesis from the breakdown of proteins.
Describe the glycemic index
It is measure of the effect of carbohydrates on blood sugar levels.
Refined carbohydrates like white bread. Polished rice, breakfast mealie meal have a high Glycemic index(GI) because they are broken down quickly thereby releasing glucose rapidly in circulation.
Whole wheat products( brown bread) sweet potatoes have a medium GI.
Brown rice roller meal, fruits , vegetables, legumes, nuts have a low GI. They breakdown slowly and release glucose gradually.
Foods with low GI breakdown slowly and release glucose gradually and they have health beenfits.
People that eat food with high GI have an increased risk to developing obesity and are susceptible to the development of diabetes, heart disease and cancer.
