Nutrition Flashcards
Why do we need vitamins and minerals?
They are essential for life – they don’t provide energy but are necessary in small amounts for life and growth
Which processes are vitamins and minerals involved in?
They act as “chemical partners” with key roles in lots of vital processes including:
• Metabolism
• Cell production
• Tissue repair
Who discovered vitamins?
Casmir Funk = biochemist born in Poland, moved to London in 1910
Name all the water soluble vitamins (9)
- Vitamin C (Ascorbic acid)
- Vitamin B1 (thiamine)
- Vitamin B2 (riboflavin)
- Vitamin B3 (niacin)
- Vitamin B5 (pantothenic acid)
- Vitamin B6 (pyridoxine)
- Vitamin B7 (biotin)
- Vitamin B9 (folate/folic acid)
- Vitamin B12 (cobalamin)
There are nine water soluble vitamins (excreted) – eight B vitamins and vitamin c
What is folate
Folate is the “natural” form of vitamin b9. It is added to foods/as a supplement as folic acid (better absorbed than that from food source)
Where are most water soluble vitamins absorbed and what is the exception
- Most water soluble vitamins absorbed in upper small intestine (duodenum) except for vitamin B12
- Vitamin B12 absorbed in ileum – binds to intrinsic factor (protein secreted by stomach). Resulting complex is absorbed across the ileal mucosa.
What are the key facts surrounding how water-soluble vitamins are absorbed and stored?
Absorption of water-soluble vitamins is rapid. Vitamin b12 and folate (b9) absorption occurs independently from sodium but the seven remaining water-soluble vitamins absorbed by carriers that are sodium cotransporters. Water soluble vitamins are not stored
Name the 4 main fat soluble vitamins
- Vitamin A
- Vitamin D
- Vitamin E (tocopheryl)
- Vitamin K
Name the vitamin D and vitamin K derivatives
Vitamin D - includes ergocalciferol (calciferol, vitamin D2), colecalciferol (vitamin D3), dihydrotachysterol, alfacalcidol (1α-hydroxycholecalciferol), and calcitriol (1,25-dihydroxycholecalciferol). Vitamin K (phytomenadione)
Why do we need vitamin K
Vitamin K is necessary for the production of blood clotting factors and proteins necessary for the normal calcification of bone
Where are fat soluble vitamins absorbed and when might this be reduced
Fat soluble vitamins absorbed by bile in large intestine and can be reduced if fat absorption is decreased e.g. by lack of pancreatic enzymes/low fat diet. These vitamins can be stored
How do humans synthesise vitamins d and k
Vitamin K – many subtypes produced by GI flora from original plant sources then absorbed (Think warfarin, antibiotics, decreased INR)
Vitamin D – dietary but also synthesised in skin via cholesterol by sunlight
What can deficiency of vitamin A be associated with
Eye defects (particularly xerophthalmia), increased infection risk. Rare in UK
What can deficiency of vitamin B (not B12) be associated with and how do we treat it
B1 – tiredness, poor appetite, weight loss, GI problems. B2 – sight loss, sore mouth B3 – tremors, GI problems, skin abnormality. B5 – heart and GI issues. B6- depression, vomiting, anaemia. B7 – skin inflammation, conjunctivitis. B9 (folic acid) - anaemia, GI disorders, palpitations.
Treatment - thiamine (B1), riboflavin (B2), and nicotinamide. In severe deficiency - treated initially by the parenteral administration of B vitamins (Pabrinex®), followed by oral administration of thiamine
What can deficiency of vitamin C be associated with
Scurvy. ‘Vitamin C therapy is essential in scurvy, but less florid manifestations of vitamin C deficiency are commonly found, especially in the elderly. Severe scurvy causes gingival swelling and bleeding margins as well as petechiae on the skin.’
What are minerals?
Inorganic substances. Minerals are required in large amounts while trace elements are only required in smaller quantities
What does the body need minerals for
Variety of functions including
Formation of bones and teeth, Essential constituents of body fluids, tissues and blood, Components of enzyme systems, Nerve function
Give examples of minerals
- Calcium
- Sodium
- Magnesium
- Potassium
- Chloride
- Phosphorus
- Iron
- Iodine
- Selenium
- Zinc
- Copper
Where do we get minerals from and what affects their absorption
Food and supplements (however, no one food provides all minerals). This is why we need healthy balanced diet. Water is also a source
Absorption may be affected by:
- Presence of other minerals/vitamins
- Components found in food
- Amount of mineral already in body
Give some examples of common mineral deficiencies and what affects they can cause
- Potassium and Magnesium - cardiac arrhythmias
- Calcium and Magnesium - osteoporosis
- Calcium and Magnesium - muscle cramps and tetany
- Zinc - hair loss and poor wound healing
- Iron – anaemia
- Copper - Wilson’s disease
Where are the nutrition guidelines derived from
National Diet and Nutrition Survey (NDSD) and the Scientific Advisory Committee on Nutrition (SACN) who advises government on diet and health
What are RNIs, LRNIs and EARs
Reference Nutrient Intakes (RNIs)
Lower Reference Nutrient Intakes (LRNIs)
Estimated Average Requirements (EARs)
Define the Estimated Average Requirements (EARs).
The EAR is an estimate of the average requirement of energy or a nutrient needed by a group of people (i.e. approximately 50% of people will require less, and 50% will require more)
Define the RNI
The RNI is the amount of a nutrient that is enough to ensure that the needs of nearly all a group (97.5%) are being met. For most vitamins and minerals, DRVs are given as Reference Nutrient Intakes (RNI). Most vitamins and minerals also have Lower Reference Nutrient Intakes
Define the LRNIs
The LRNI is the amount of a nutrient that is enough for only a small number of people in a group who have low requirements (2.5%) i.e. the majority need more.
What is the safe intake of nutrients
The Safe intake is used where there is insufficient evidence to set an EAR, RNI or LRNI. The safe intake is the amount judged to be enough for almost everyone, but below a level that could have undesirable effects.
When would a person be recommended to take higher levels of folic acid
During pregnancy – its recommended women of child bearing age take 400μg folic acid supplement daily until 12th week of pregnancy. This prevents birth defects of the central nervous system (aka neural tube defects) including spina bifida
When would a pregnant woman be advised to take higher supplements of folic acid than normal
If family history of neural tube defects - higher dose of 5mg of folic acid daily recommended. Women with diabetes and those taking anti-epileptic medicines may also need to take a higher dose of folic acid
Which vitamins are pregnant women advised to take and also avoid
Advised to take vitamin D, folic acid and vitamin C
Avoid excess vitamin A as can be teratogenic.
Which vitamins are babies (breastfed and bottle fed) recommended to have
Breastfed babies (birth to one year of age) - daily supplement containing 8.5 - 10μg of vitamin D
Babies fed infant formula – not required until receiving less than 500ml of infant formula a day
Children aged 1 to 4 years old - daily supplement containing 10μg of vitamin D
Who needs extra vitamin A and C
Children aged six months to five years – daily supplement of vitamins A and C (often combined with vitamin D)
Precautionary measure - ensure requirements are met (difficult to be certain diet provides a reliable source)
Babies fed infant formula – not required until receiving less than 500ml of infant formula a day
Who is at an increased risk of vitamin D deficiency
Those living in the UK, including people at increased risk of vitamin D deficiency, should consider a daily supplement containing 10μg (400 IU) of vitamin D
People at higher risk of deficiency include those:
With limited sun exposure
With dark skin (for example African, African-Caribbean, or Asian or Middle-Eastern ethnic origin)
Vitamin D deficiency can also occur in people who:
• Cover up their skin for cultural reasons (for example Muslim women) or for health reasons (for example people with skin photosensitivity or a history of skin cancer).
• Spend very little time outdoors (for example those who are housebound or institutionalized).
• Are at increased risk of nutritional deficiency, for example vegans and those who do not eat fish, or generally have a poor diet
Are at increased risk of nutritional deficiency
Are pregnant or breastfeeding
Are elderly (65 years and older)
Have certain conditions or are taking certain drugs
Are obese or have had gastric bypass surgery
Have a family history of vitamin D deficiency
How do we treat vitamin D deficiency
Vitamin D deficiency caused by intestinal malabsorption or chronic liver disease usually requires vitamin D in pharmacological doses.
Vitamin D requires hydroxylation by the kidney to its active form, therefore the hydroxylated derivatives alfacalcidol or calcitriol should be prescribed if patients with severe renal impairment require vitamin D therapy
Which groups of people may benefit from supplementation
- Some vegans
- People in certain demographic groups – infants and children, adolescents (iron deficiency), pregnancy and breastfeeding, elderly, ethnic minorities
- Chronic alcoholism - poor diet and poor GI absorption
- Innate GI malabsorption e.g. coeliac, inflammatory bowel disease (IBD)
- Chronic kidney disease (CKD) – vitamin D
- If prescribed certain medications e.g. isoniazid
Give some examples of fortified products
Addition of nutrients to appropriate food vehicles e.g.
• Vitamin D fortified margarine
• B vitamins and iron in cereals
• White and brown flour fortified with calcium, iron, thiamine and niacin
• Fluoride in drinking water
What are supplements and how beneficial are they
Products which contain vitamins, minerals and often other ingredients. Promoted on basis that taking additional vits and minerals will be beneficial. However the evidence for this in most cases is unsubstantiated. We have already discussed those for whom specific recommendations are in place.
What are the problems surrounding supplementation
- Toxicity and accumulation e.g. iron
- Supplements are expensive
- Cause complacency - bad diet
- Legal status practically no control
- Dose, claims quality control, availability
- Not viewed as a medicine – thus difficult to offer advice
- Interactions
Give some examples of interactions between supplements and drugs
• Methotrexate and folic acid – beneficial. Protect vs. side-effects of methotrexate
• Iron and Vitamin C – beneficial. Vitamin C enhances iron absorption
• Tetracyclines and metal salts e.g. iron or magnesium. Reduces absorption of antibiotic therefore take antibiotic at least 2 hours before or 6 hours after metal salt supplement
• Calcium and corticosteroids. Corticosteroids reduce absorption of calcium from the GI tract, increasing risk of osteoporosis
Good Practice – Always ask patients about any supplement they take
What is the role of the pharmacist in mineral and vitamin nutrition
- Advice to public about healthy diet
- Identification of patients who may benefit from additional supplementation
- Aware of common symptoms of deficiency
- Be able to recommend appropriate supplements
- Prevent interactions
