Intro to Nutrition Flashcards
What is EAR?
Estimated Average Requirement
Half the population usually needs more than this, and half usually needs less
What is LRNI?
Lower Reference Nutrient Intake
Sufficient for the few people who have low needs, but not meeting the needs of 97.5% of the population (2 standard deviations below the EAR)
What is RNI?
Reference Nutrient Intake
Sufficient for about 97.5% of people (2 standard deviations above the EAR). If the average intake of a population is at RNI, the risk of deficiency is very small
What is safe intake?
Range for which there is not enough information to estimate RNI, EAR or LRNI. Sufficient for almost everyone, but not so large as to cause undesirable effects.
What is key to maintaining a healthy weight?
Energy balance
Energy intake = energy expenditure
What does energy expenditure depend on?
- Basic metabolic rate (depends on age, weight & sex)
* Amount and intensity of physical activity
What are macronutrients?
Fats, carbohydrates and proteins
Can protein be stored? What happens in starvation?
No storage of protein, but in starvation muscle tissue can be metabolised for energy or to provide amino acids for other reactions
Can excess carbs and fats be stored?
Excess carbohydrates and fats can be stored. Can be used immediately for energy generation
What is the body’s main source of energy?
Fat stores are main source of energy (80-90%)
How much protein does an average adult require a day?
Around 0.75g per kg per day (75kg man requires about 50g protein/day)
How much protein is an athlete/body builder recommended?
1.2-1.7 g per kg per day
What is the nitrogen balance in a healthy adult?
Nitrogen intake = nitrogen excretion
What is a negative nitrogen balance? When does it occur?
Intake < excretion
Occurs during fasting/illness – body breaking down proteins for energy
What is a positive nitrogen balance? When does it occur?
Intake > excretion
Occurs during growth, pregnancy – body is building new tissue
What 9 amino acids cannot be synthesised by humans? How are they obtained?
Many Very Happy Little Pigs Take Iced Lemon Tea (MVHLPTILT)
o Methionine o Valine o Histidine o Leucine o Phenylalanine o Tryptophan o Isoleucine o Lysine o Threonine
Must be obtained from diet
What is triacylglyercol?
A triglyceride (TG, triacylglycerol, TAG, or triacylglyceride) is an ester derived from glycerol and three fatty acids
The main constituents of body fat in humans and other vertebrates, as well as vegetable fat.
How many calories does 1g of fat compared to 1g of carb/protein provide?
Fat –> 9kcal
Carb/protein –> 4kcal
What is adipose tissue? What is its role?
Adipose tissue, or fat, is an anatomical term for loose connective tissue composed of adipocytes. Its main role is to store energy in the form of fat, although it also protects vital organs and gives our body and face their shape.
Adipose tissue can store an unlimited amount of fat.
What are the different fatty acids that triacylglycerols contain?
- Saturated
- Mono-unsaturated
- Polyunsaturated
- Trans (hydrogenated)
Describe saturated fatty acids
No double bonds, found in meat and dairy
Describe mono-unsaturated fatty acids
One double bond, found in olive and peanut oil
Describe polyunsaturated fatty acids
More than 1 double bond, found in corn and sunflower oil
Describe trans (hydrogenated) fatty acids
Trans double bonds, found in cakes, biscuits, pastry
What are the recommended % of dietary energy intake for fat types?
Saturated - 11%
Mono - 12%
Poly - 6%
Trans - <2%
Total fat <35% (30% desirable)
Which fatty acids can the body not synthesise?
Omega 6 and omega 3
What are the types of carbohydrates?
- Polysaccharides – mainly starch
- Disaccharides – mainly sucrose
- Monosaccharides – mainly glucose and fructose
- Non-starch polysaccharide (dietary fibre)
What are vitamins? What amounts are they required in?
Organic compounds required for normal metabolic function, which cannot be synthesised in the body – deficiency results in disease which can be treated by restoring appropriate levels of the compound
Required in small amounts (µg – mg)
What is function of vitamins?
- Most coveted into molecules that act as coenzymes
- Others act as transcriptional regulators and signalling molecules
- Some act as antioxidants
Which vitamins act as coenzymes?
All B vitamins, C and K
What vitamins act as transcriptional regulators and signalling molecules?
A and D
What vitamins act as antioxidants?
A, C and E
Which vitamins are fat soluble?
E, K, A, D
Which vitamins are water soluble?
B1, B2, B3, B5, B6, B7, B9, B12, C
What is vitamin B1? What is its role? What is the effect of deficiency?
Thiamin
Cofactor in decarboxylation reactions (CO2) released – e.g. link reaction, Krebs cycle
Beri –beri; muscle weakness, nerve damage, can affect heart
What is vitamin B2? What is its role? What is the effect of deficiency?
Riboflavin
Constituent of cofactors e.g. flavin adenine dinucleotide (FAD); involved in many aspects of metabolism, fats, carbohydrates, proteins
Very rare – cofactors bind tightly to enzymes and efficiently conserved
What is vitamin B3? What is its role? What is the effect of deficiency?
Niacin
Constituent of cofactors e.g. NADH
Pellagra – diarrhoea, depression, dermatitis, death
What is vitamin B5?
Pantothenic acid
Constituent of coenzyme A – energy metabolism, fat metabolism
Unknown – found in almost all foods
What is vitamin B7? What is its role? What is the effect of deficiency?
Biotin
Prosthetic group. Acts as carrier for CO2 in carboxylation reactions e.g. fat synthesis
Very rare
What is vitamin B6? What is its role? What is the effect of deficiency?
Pyridoxal phosphate
Cofactor for enzymes involved in protein metabolism, haem synthesis, neurotransmitter synthesis; modulates steroid hormone action
Irritability, depression, and confusion; inflammation of tongue or mouth
What is vitamin B9? What is its role? What is the effect of deficiency?
Folic acid
1-C transfers, particularly in DNA synthesis
Neural tube defects – spina bifida, anencephaly, macrocytic anaemia
What is vitamin B12? What is its role? What is the effect of deficiency?
Cobalamin
Required for only 2 reactions (methionine synthesis, odd-chain fatty acid metabolism)
Only found in animal products
Macrocytic anaemia,
irreversible neurological damage.
Commonly caused by autoimmune disease preventing absorption
What is vitamin C? What is its role? What is the effect of deficiency?
Collagen synthesis. Also role as antioxidant
Scurvy – symptoms caused by weakened collagen
What is vitamin A? Deficiency?
Vision (rod cell function). Transcriptional regulator
Blindness, susceptibility to infection, birth defects
What is vitamin D? Deficiency?
Bone formation & maintenance; also roles in immune regulation, cell differentiation, muscle function
Rickets in children, osteomalacia in adults.
What is vitamin E? Deficiency?
Acts as an anti-oxidant; its main role is to prevent lipid oxidation in membranes
Deficiency in fat malabsorption (e.g. CF), causes neurological problems
What is vitamin K? Deficiency?
Cofactor for enzymes which activate blood clotting proteins. May also be involved in bone maintenance
Rare in healthy adults. Deficiency in newborns causes bleeding; babies given vitamin K at birth.
What are the key minerals?
Iron Iodine Zinc Fluoride Calcium Phosphate Magnesium
What are the trace elements?
Cobalt, copper, chromium, manganese, selenium
What is function of sodium and potassium?
Major electorates within cells (K+) and in extracellular fluid (Na+)
What is the recommended sodium intake?
<6g/day
What are major dietary sources of salt?
Processed food?
Bread, cereals, processed meat, ready meals
What can a high sodium intake lead to?
Contributes considerably to the risk of cardiovascular disease
How can inadequate intake lead to nutritional deficiency?
- Food availability (poverty, disability)
- Food choices (cost, convenience, limited range, vegans)
- Problems with eating (sore mouth, dysphagia, eating disorders)
How can inadequate absorption lead to nutritional deficiency?
- Problems with fat absorption affects fat soluble vitamins (cystic fibrosis, coeliac disease, Crohn’s disease)
- Pernicious anaemia (B12 absorption)
What can iron deficiency anaemia arise from?
A result of persistent blood loss – gastric ulceration, colon cancer, excessive menstrual loss
- Pregnancy
What can a folic acid deficiency be due to?
Pregnancy
Globally, what deficiencies are most important?
Iron, vitamin A, iodine and zinc
What can a vitamin A deficiency lead to?
Blind
What % of Europe has an insufficient iodine intake?
More than 50%
Definition of malnutrition?
Characterised by inadequate or excess intake of protein, energy, and micronutrients such as vitamins & minerals
What are the clinical effects of malnutrition?
- Neurological/metabolic
- Cardiac/haematological
- Respiratory
- GI
- Reproductive
- Hepatic/renal
- Immunity
- Musculoskeletal/integumentary
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Who does a vitamin C deficiency still affect?
Most of the UK population obtain well over the RNI for vitamin C (NDNS 2019)
Vitamin C deficiency within UK’s low-income population
What can a vitamin D deficiency lead to?
Osteomalacia (adults) & rickets (children)
Also possibly in increased risk of:
- Auto-immune diseases (MS, type 1 diabetes)
- Some cancers (breast, colon ovarian, rectal & prostate cancer)
- Muscle weakness/falls in adults > 50
What can cause a vitamin B12 deficiency?
- Vegans not taking supplements
- Prolonged treatment with acid-blocking drugs (e.g. PPIs) affects as many as 20% of the elderly population, can affect absorption
What can vitamin B12 deficiency lead to?
B12 deficiency can cause anaemia, but also serious, and irreversible neurological damage. Common symptoms include numbness and tingling of toes and fingertips
If untreated, more serious symptoms include limb weakness, poor coordination, altered gait, incontinence …. death
Why is there an increased requirement for folic acid in pregnancy?
DNA synthesis
Pregnant women and women trying for a baby should take 400μg of folic acid daily until 12th week of pregnancy.
What can folic acid deficiency in pregnant women lead to?
Neural tube defects – anencephaly/spina bifida - incidence can be significantly decreased by folate supplementation (USA add folate to flour)
What can an inadequate iodine status in pregnancy lead to?
Affects cognitive outcomes in children