Vitamins, Minerals and Nutrition Flashcards by Elysia Kirby

Q

DRVs =

A

Dietary Reference Values

= estimates of the energy and nutrients needed by different groups of healthy people in the UK

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Q

Estimated Average Requirement (EAR) =

A

The level of a nutrient required to satisfy about 50% of the population

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Q

Reference Nutrient Intake (RNI)

A

Set 2 standard deviations above the mean (EAR) and will meet the individual requirements of 97.5% of the population

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Q

GDAs

A

Guideline Daily Amounts

Intended as guidance for consumers in their understanding of their recommended daily consumption of energy (calories), fat and saturates and a base against which the content of individual foods can be compared

Currently no GDAs for children

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Q

BMR (Basal Metabolic Rate)

A

Approx 60% of energy obtain by food oxidation used to maintain body function = basal metabolic rate
e.g. heart beat, inflating lungs, maintaining ion gradients, synthesising bio-molecules e.g. proteins, hormones, DNA, RNA, fat etc.

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Q

Small Intestine

A

Duodenum (proximal)
o First part of small intestine
o Receives secretions from pancreas (enzymes for protein digestion) and bile from gallbladder to aid digestion
Jejunum (middle)
Ileum (distal)
o Inner surface highly folded into villi – increases SA for absorption

Attached to body wall by mesentery

Function: Nutrient Absorption

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Q

Large Intestine

A

-	Constitutes 
o	Caecum 
o	Ascending colon
o	Transverse colon
o	Descending colon 
o	Sigmoid colon 
o	Rectum 
o	Anal canal

Function
o Water absorption
o Formation of faecal mass
o Secretion of mucus

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Q

Accessory Organs of GI tract

A

Pancreas – enzyme secretion into duodenum

Liver

Bile production
Detox – drugs, alcohol
Albumin production – protein that maintains osmotic pressure
Production of clotting factor precursors
Storage of glycogen

Gallbladder – stores and secretes bile into duodenum; emulsifies lipids

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Q

Omentum

A

Covers GI tract
Consists of greater and lesser omenta
Greater omentum hangs from greater curvature of stomach like a curtain, also contains extra-peritoneal tissue; lymph nodes, lymph vessels, small blood vessels, variable amounts of fat. Has irregular lacy appearance.

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Q

Peritoneum

A

= membranes of the abdomino-pelvic cavity

Visceral peritoneum: covers external surfaces of most digestive organs

Parietal peritoneum: lines body wall

Peritoneal cavity = potential space between the two

Peritoneal fluid = normal lubricating fluid found in peritoneal cavity

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Q

digestion of carbohydrate in the oral cavity

A

Oral cavity → Mechanical (mastication exposes terminals to enzymatic action) + Chemical (enzymatic – salivary amylase secreted from serous cells in salivary glands)

Salivary amylase

Secreted by serous acini of parotid and submandibular salivary glands
Optimal pH= 6.7
Action begins in oral cavity, assisted by mechanical breaking up of polysaccharides during mastication
Mode of action = hydrolysis of α-1-4 linkage in polysaccharides → mixture of oligosaccharides (di/tri-saccharides)
Works for 1/2hrs in stomach before being deactivated by gastric acids

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Q

digestion of carbohydrate in GIT

A

GIT → Chemical (enzymatic)

Pancreatic amylase
- Secreted from pancreatic exocrine acini into duodenum through the pancreatic duct – along with bicarbonates raises pH to optimum for amylase to work
- Optimum pH=6.7-7.0
- Mode of action = hydrolysis of α-1-4 linkage
- Responsible for digestion of more complex carbohydrate, take longer to break down to disaccharides (maltose) or oligosaccharides (dextrins)
NB: salivary & pancreatic amylases cant completely digest carbohydrates

*Brush border enzymes: Maltase, Sucrase, Lactase **
Found on membrane surface of micro-villi (brush border) of epithelial cells lining small intestines
Optimal pH=7-8
Mode of action = hydrolysisng disaccharides → monosaccharides

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Q

absorption of glucose from the small intestine at the cellular level

A

Villi & Microvilli (brush border) -> Increase SA, facilitates absorption
Monosaccharides = absorbable form of carbs

Glucose & Galactose

Enter epithelial cells of intestine through the apical border via active transport (against concentration gradient) using sodium dependant co-transporters (Na-K pump requires energy)
Leave the cells through the Basolateral side using facilitated diffusion and glucose co-transporter- 2 (GLUT-2) into the circulation (no energy required)

Fructose
- Enters (GLUT-5) and leaves (GLUT-2) the epithelial cells using facilitated diffusion (no energy required)

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Q

Factors affecting carbohydrate absorption

A

Faster through intact mucosa; absorption decreased if inflammation or injury to the mucosa.
Thyroid hormones ↑ the rate of absorption of glucose.
Mineralocorticoid: e.g. Aldosterone ↑ the rate of absorption.
Na+ concentration: high concentration ↑ the rate of absorption

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Q

role of insulin in glucose homeostasis

A

Insulin = hormone secreted by ß-cells in islets of Langerhans in pancreas (endocrine glands)
Responsible for regulating levels of glucose in blood by stimulating body cells to take up glucose – all body cells sensitive to insulin except: brain, liver and muscles during exercise

Structure of Insulin:
2 polypeptide chains A & B linked by a disulphide bond

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Q

Glucagon

A

= hormone secreted by α- cells in islets of Langerhans in pancreas

Responsible for converting glycogen stored in liver -> glucose and releasing it in blood when blood glucose levels low
Also stimulates gluconeogenesis from untraditional mechanisms (fat/protein sources) – used in case of starvation

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Q

➢ Clinical significance of insulin deficiency

A

Insulin deficiency 
(Type 1 – autoimmune disease) 
Insulin resistance (Type 2 – unresponsive cells)

–> leads to hyperglycaemia (causes the symptoms and complications of diabetes) and diabetes mellitus.

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Q

➢ Symptoms and complications of diabetes and its relevance to oral health and dental management

A

impaired wound healing
dry mouth
nausea
yeast infections

Diabetes -> damage to blood vessels -> more susceptible to collecting cholesterol -> blockage of blood vessels: macrovascular, microvascular

Dental Complications:

Dry mouth
Periodontal disease
Loss of teeth
Impaired/delayed healing
Infections

Dental management of diabetic patients
• Regular visits to dentist and dental hygienist
• Maintenance of oral hygiene
• Regular periodontal check and management
• Antibiotic coverage for surgeries (surgical extraction, implants)
• Controlled blood sugar levels before any surgical intervention
• Mouth wash
• Artificial saliva if required

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Q

Nutrition and Caries

A

proteins - can adsorb to enamel surface and prevent remineralisation
dehydration -> reduced salivary flow
Caesin (milk protein) promotes natural remineralisation
fluoride insufficient -> caries prone
fluoride excess -> fluorosis

Vit D deficiency -> decreased Ca -> poorly mineralised enamel, enamel hyperplasia, rickets
Vit E def (rare) -> disturbed enamel formation
Vit A def -> enamel hyperplasia and malformed dentine

fermentable dietary components (carbohydrate)

pyruvate -> lactic acid/acetic acid

sucrose = worst carb
- bacteria can use to produce extracellular polymer
sucrose = glucose + fructose
Glucan (polymer of glucose) + Fructan (polymer of fructose) -> plaque

sugar substitutes = non-fermentable

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Q

Nutrition and Periodontal disease

A

nutrition modulates immune response .’. poor nutrition -> poor wound healing

vit A -> essential in maturation of epithelial tissues

vit D -> maintains blood Ca levels and metabolism of osseous (bony) tissues - may be associated with periodontal disease

vit C *(humans can’t make it C = essential vit) -> required for collagen maturation
deficiency -> tissue bleeding, marked gingivitis, increased risk of period disease

vit B complex -> can increase periodontal wound healing

dairy - inverse relationship between intake and period

alcohol - may be associated with increased severity of CAL

fish oils -> anti-inflammatory actions

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Q

Fat soluble vitamins

Study These Flashcards

A

A
D
E
K

fat must be present in diet to adsorb these vitamins

can accumulate in adipose and can reach toxic levels

Q

Water Soluble vitamins

Study These Flashcards

A

C
B6
B12 
Biotin
Folate 
Niacin 
Rriboflavin (B2)
Thiamin (B1)

Excess water soluble vitamins excreted in urine .’. generally less toxic

Q

Vitamin C (Ascorbic Acid)

Study These Flashcards

A

RNI = 40 mg/day

Sources = Fruiit, veg, liver

Functions =

Antioxidant
Required for iron (Fe) adsorption
Required in synthesis of many biomolecules (esp. collagen)

Deficiency -> 
Scurvey 
-->
loose teeth
superficial bleeding 
fragile blood vessels
poor healing
compromised immunity 
mild anaemia (due to decreased  Fe adsorption)

Q

Vitamin D

Study These Flashcards

A

Most toxic of all vitamins; in high doses -> nausea and muscle weakness. V high doses -> increased Ca adsorption & bone resorption, resulting increased Ca levels in body fluids can lead to calcification of arteries and organs.

T-Dehydrocholesterol (from liver) = inactive
+ UV –>
Cholecalciferol (Vitamin D - also from diet) = inactive
–> Activated by hydroxylation

Controls serum Ca & phosphate levels - critical for correct development of bones and teeth

Folate (Folic Acid)

- one of B group vitamins RNI = 200ug/day Sources = green leafy veg, liver (where stored), nuts, cereals Functions = Carrier of 1 carbon units *very important in many biosynthetic reactions Deficiency: occurs 2-3 months -> - megaloblastic anaemia - fatigue - hair loss - birth defects -> neural tube defects e.g. spina bifida, anencephaly - glossitis, mouth ulceration, angular chelosis = general symptoms of B group vitamin deficiency Activation: Folic Acid not active form of vitamin, needs to be reduced to tetrahydrofolate - occurs via: dihydrofolate reductase = enzyme targeted by anti-cancer drugs *Coenzyme in many reactions involving transfer of 1C atom to other compounds. Single C groups can be carried in N5, N10 or bridged between both these Nitrogens. E.g. in synthesis of dTMP (t base in DNA) - v.important in rapidly dividing cells e.g. bone marrow cells (->RBCs), hair follicles, mucosal cels, cancer cells - explains why chemotherapy causes hair loss. Methotrexate inhibits dTMP production.

Vitamin B12 | cobalamin

RNI = 1.5ug/day (NB: a healthy adult will have enough B12 stored in their liver to last years) Sources = only produced by microorganisms - naturally we obtain by eating animals, eggs and dairy products Functions = 1. B12 required in folate metabolism --> FOLATE TRAP in deficiency - Impacts DNA synthesis, important in rapidly dividing cells 2. Required by methylmalonyl CoA mutase (B oxidation of odd chain fatty acids) Deficiency -> - megaloblastic (pernicious) anaemia; due to impact on folate metabolism - Neurological disorders; due to impact on odd carbon FA metabolism) NB: dietary deficiency found only in strict vegans/vegetarians. Deficiency due to adsorption problems more common. B12 binds a glycoprotein (intrinsic factor; secreted by parietal cells) in stomach vitamin-intrinsic factor complex recognise and absorbed

Vitamin K

=> Blood Clotting and formation of mineralised tissues Sources = 1 - Made by gut bacteria (70%) 2 - Diet; green veg, liver, egg yolk (30%) Functions = ESSENTIAL in formation of CARBOXYGLUTAMATE Deficiency Causes: - Dietary deficiency - Long term antibiotic use -> decreasing levels of gut bacteria - Anticoagulant drugs e.g. Warfarin (= vit K antagonists) - inhibit clotting by preventing gamma carboxylation NB: Newborns have sterile guts .'. can't make bit K in first week of life

Vitamin A

RNI = Sources = Functions = Deficiency ->

Thiamin (Vitamin B1)

RNI = Sources = Functions = Deficiency -> Beriberi disease

Pyridoxine (Vitamin B6)

RNI = Sources = Functions = Deficiency ->

Tocopherol (Vitamin E)

RNI = Sources = Functions = Deficiency ->

Rriboflavin (Vitamin B2)

RNI = Sources = Functions = Deficiency ->

Niacin (Vitamin B3)

RNI = Sources = Functions = Deficiency ->

Pantothenic acid

RNI = Sources = Functions = Deficiency ->

Biotin

RNI = Sources = Functions = Deficiency ->

Which vitamin is a coenzyme for methylmalonyl CoA mutase in B oxidation of odd C FAs

B12 In absence of B12 L-Methylamlonyl CoA accumulates; causing demyelination of nerve cells because disrupts FA synthesis (get branched FAs) --> Irreversible, neurological damage

A primary deficiency in which vitamin causes a secondary folate deficiency?

B12 Even if folate in diet -> deficiency due to FOLATE TRAP N5-Methyl tetrahydrofolate + Hemcysteine ----> Methionine + Tetrahydrofolate Reaction occurs via methionine synthase with vitamin B12 as a coenzyme. (Tetrahydrofolate accepts methyl group in different reactions and is converted back to Nf-Methyl tetrahydrofolate) * ONLY reaction that can utilise N5-Methyl tetrahydrofolate * If B12 deficient methionine synthase reaction stops and eventually all folate trapped as Nf-Methyl tetrahydrofolate which can't be used for anything

Which vitamin required in formation of Carboxyglutamate? What is the significance of Carboxyglutamate?

[Carboxyglutamate = amino acid glutamate with extra carboxyl group added to gamma carbon end of it's side chain] Glutamate -----> γ-carboxyglutamate (carboxylation rxn: Enzyme + vit K) when vit K deficient or antagonised by drug can't synthesise γ-carboxyglutamate & protein function impaired - extra carboxyl group allows binding of Ca ions necessary for functions Blood Clotting: Factors II, VII, IX, X contain γ-carboxyglutamate Bone Mineralisation: Osteocalcin = protein involved in bone mineralisation

Calcium (Ca)

Absorption greatly increased by parathyroid hormone and active Vitamin D! ``` Functions: – Structural in skeleton – Intracellular second messenger (like cAMP) – In transmission at synapses – Muscle contraction – Blood clotting ``` ``` Deficiency: due to Ca deficient diet, secondary vitamin D deficiency or Malabsorption → Ostemalacia (rickets in children) – usually caused by secondary deficiency in vit D, not aided by Ca poor diet → Oral problems – Incomplete mineralisation of teeth – Increased caries risk – Tooth malformation – Increased risk of perio problems – People aged 20-30 consuming ```

Phosphorus

RNI = 550mg/day – higher during growth, pregnancy, lactation, post menopause. Sources: Most foods – dietary deficiency unknown Adsorption: 50-70% in diet absorbed (enhanced by vitamin D) Functions: – With Ca in mineralised tissues – Biological buffer – Required for many biomolecules and processes e.g. phosphorylated proteins, ATP, DNA, RNA etc. Deficiency: usually due to *kidney malfunction*, aluminium in antacids, total starvation. If severe will affect functioning of all cells. Impact on bone metabolism could → rickets and Ostemalacia (softening of bones). Oral problems similar to Ca deficiency. Excess: Disturbance of Ca balance, *increased porosity of skeleton*.

Iron (trace element)

RNI = 8.7mg/day men ; 14.8mg/day – higher RNI than biological requirement to compensate for inefficient absorption Sources: Dietary iron has 2 forms 1. Haem iron : liver, meat – from haemoglobin/myoglobin = rapidly absorbed 2. Non haem iron : green veg, cereals = slowly absorbed (aided by meat proteins, vit C, alcohol) Adsorption: Tannins (found in tea), Ca, polyphenols, phytates (found in legumes and whole grains), oxalate (green leafy veg) can decrease absorption of non-haem iron. Some proteins in soybeans also inhibit non-haem iron absorption. Functions: – In many proteins and enzymes; oxygen transport proteins, electron transport proteins etc. Deficiency: due to - Inadequate dietary intake Blood loss (menstruation, ulcers etc.) → Anaemia Excess: Fe = toxic, deposited in tissues which distrupts function (free radical damage) Transported in blood bound to Transferrin – stored bound to ferritin in bone marrow & spleen, haemosiderin in liver.

Iodine (trace element)

THYROID Functions: – Synthesis of thyroid hormones by thyroid glands – Control of metabolic rate – Essential for brain development in early life Deficiency → reduced synthesis of thyroid hormones – goitre (abnormal swelling of the thyroid gland that causes a lump to form in the neck) in children and adults and mental retardation in neonates

Na (cationic electrolyte)

``` Functions: – Main cation in extracellular fluid – Controls extracellular fluid volume – Na gradient used in transport of molecules e.g. glucose pump – Neuromuscular transmission ``` Deficiency: Due to: vomiting, diarrhoea, diuretics, Addison’s disease, renal problems Causes: water loss, decreased plasma volume → circulatory failure and collapse Excess: role in hypertension in sensitive individuals – weak relationship

K (cationic electrolyte)

.

Chloride (anionic electrolyte)

RNI = m2.5g/day – higher during Source: meat, sea food, eggs, salt Functions: – Major anion in body Deficiency: rare – usually associated wit Na loss

Copper (trace element)

.

Magnesium

.

Zinc (trace element)

.

Chromium (trace element)

INSULIN Functions: – Improves insulin function by increasing insulin binding to cells, insulin receptor number and phosphorylation of the insulin receptor → increased insulin sensitivity Deficiency: only likely in those only eating refined/processed foods or those on intravenous nutrition. Exercise appears to increase excretion of chromium. Diets high in simple sugars increase urinary chromium excretion in adults.

Selenium (trace element)

.