CHEMPATH: Nutrition Flashcards
List 5 fat-soluble vitamins.
List 6 water-soluble vitamins.
Which FSV can be tested for? Why are these tests rarely done?
Stored in adipose tissue (so very few patients in UK will be deficient in these). People in the UK are more at risk of excess vitamins.
- Vitamin A is rarely tested – may be tested if e.g. bariatric surgery presenting with colourblindness
- Vitamin D deficiency is quite common (25-hydroxyvitamin D is the precursor that is measured – but this is not the most specific test because at cellular level 1,25-hydroxyvitamin D would be better but this is expensive)
- Vitamin E – rarely causes anaemia and neuropathy, some suggest it may be a marker for malignancy.
- Vitamin K – causes defective clotting if deficient; if high INR and bleeding on warfarin then can be given vitamin K can be given as a treatment.
What deficiencies in water-soluble deficiencies/excesses may occur? How do they present? How common are these?
More common to have a deficiency in (rather than excess)
Beri-Beri – vitamin B1** / **thiamine deficiency:
- Wet – characterised by CVD (patients may present with oedema and other heart failure features)
- Dry – characterised by neurological disease
- Some may have Wernicke’s encephalopathy
- Pabrinex is given to alcoholics to prevent Wernicke’s encephalopathy
The test for B1 takes a long time so people are usually treated with thiamine on the assumption
B2 deficiency – glossitis; may be measured in serum but rarely done
B3 deficiency= pellagra (niacin/B3 deficiency) is characterised by a TRIAD of:
- Diarrhoea
- Dermatitis
- Dementia
- Death (if untreated)
- Suspect this deficiency in old patients with dementia and dermatitis. No test available.
B6 deficiency – dermatitis, anaemia. Excess can cause neuropathy. Test not done in clinical practice.
Cobalamin/B12 deficiency – patients with AI conditions such as diabetes/thyroid disease may be at risk of other AI conditions e.g. pernicious anaemia. Measured commonly in serum as may be caused by pernicious anaemia.
Vitamin C ascorbate – rare nowadays à scurvy
Folate deficiency – important to measure in macrocytic anaemia (low Hb and high MCV), folate deficiency can cause neural tube defects to foetus.
Which trace elements can cause disease when in excess/deficient?
-
Iron:
- Deficiency –> microcytic hypochromic anaemia
- Excess may be caused by haemochromatosis. Can result in infertility due to deposition in testes à 1o hypogonadism.
- Iodine: deficiency early on can cause later goitre and thyroid deficiency in life. But cereals are fortified in UK with iodide/iodine.
- Zinc: rarely measured but may cause dermatitis in deficiency
-
Copper : deficiency can cause anaemia but excess may be caused by Wilson’s.
- Caeruloplasmin is a copper-binding protein which is LOW in Wilson’s disease
- Fluoride: deficiency can cause dental caries, fluorosis (problem with staining of teeth)
Which protein is low in Wilson’s disease?
Caeruloplasmin is a copper-binding protein which is LOW in Wilson’s disease
What is the triad of pellagra? Which vitamin causes this?
- Diarrhoea
- Dermatitis
- Dementia
- Death (if untreated)
B3/niacin
Which vitamin deficiency causes Beri Beri?
B1/thiamine
What are the food group compositions of an ideal diet?
- 50% carbohydrates
- 33% fat (western diets have gradually increased in fat)
- 17% protein
What is most energy expenditure made up of?
Resting energy expenditure (REE)
This cannot be changed
But intake and exercise may be altered
Which hormones affect energy homeostasis?
- INSULIN release after eating causes the feeling of satiety and causes an increase in energy expenditure (thermogenesis)
- White adipose tissue makes up the majority of adipose tissue in the body (largest endocrine gland in the body)
- ADIPONECTIN is produced by adipose tissue BUT this is reduced in obese people and may lead to insulin resistance
- LEPTIN is an anti-hunger hormone also produced by white adipose tissue
- GHRELIN is a hunger-hormone
- PYY is a satiety hormone that is produced in the intestines (PYY levels increase after eating a meal)
NOTE: fat content is the most variable component of body composition (10-35%)
What is the human body composed of mostly?
Normally: 98% O2, C, H, Na, Ca
- 60-70% water
- 10-35% fat (very variable)
- 10-15% protein (fairly constant)
- 3-5% minerals
How does BMI affect mortality?
Low - usually due to cancers
High - due to CVD
How is obesity defined? What about overweight in South Asians?
-
Body mass index (BMI) = weight/height2
- 25-30 = overweight
- >30 = obese
- >40 = morbid obesity
NOTE: > 23 is considered overweight for South Asians – this is because South Asians have a tendency to develop central adipose tissue and they are at increased risk of diabetes and cardiovascular disease due to visceral adiposity
What is increased waist circumference linked to? What are tthe cut-offs?
Linked to CHD
What are the complications of obesity?
- Obstructive sleep apnoea is a common issue in obesity – airways collapse waking the patient up several times at night
- Obesity increases the risk of 12 types of cancer
- Gynaecological problems include PCOS which can affect fertility
- Western diet has increased in fat and decreased in CHO
What is the daily required protein intake for males/females?
- Normal intake (daily) à used for protein synthesis/breakdown/oxidation
- Male - 84 g
- Female - 64 g
What are the 3 categories of proteins by use?
- Indispensable - cannot be made in the diet and must be obtained from the diet e.g. leucine
-
Conditionally indispensable - amino acids that are needed at certain parts of your life e.g. cysteine
- Some amino acids cannot be synthesised when you are young
- The foetus may need certain amino acids during pregnancy (i.e. cysteine)
- Dispensable (the body can produce them) – there are 5 of these e.g. alanine
List 3 assessments for protein intake.
- Nitrogen excretion and balance
- Tracer techniques
- Clinically look at muscle bulk
Which are the ‘best’ fatty acids? Which are the ‘worst’?
- Polyunsaturated fatty acids (PUFA) are good lipids AKA essential fatty acids (EFA)
- Trans-fatty acids are bad
What determines levels of LDL cholesterol?
Dietary fat
- Patients with high saturated fat –> high LDLs
- Patients with high intake of PUFA –> lower cholesterol (mainly LDL)
What are the benefits of HDLs? What can alter HDL levels?
- Increased HDL is associated with reduced ischaemic heart disease risk
- Women have higher HDL levels
- Alcohol can cause an increase in HDLs
- Obesity lowers HDLs
Does fasting have any effects on cholesterol levels?
No, HDL/LDL do not change with fasting (so no need to fast before test)
But TGs change with fasting
What are TGs? How are they absorbed from food?
- TGs are made up of glycerol and fatty acids
- Pancreatic lipase breaks down the fatty acids by hydroxylation to make monoglycerides which are then absorbed in the intestine
- Fatty acids are absorbed, assimilated and deposited in adipose tissue
Fatty acids –pancreatic lipase hydroxylation–> monoglycerides
