Nutrition Flashcards
Why is a healthy diet essential?
It provides sufficient energy and nutrients to maintain normal physiological functions, and permit growth and replacement of body tissues.
Our diet also has a major effect on risk of disease. So a healthy diet must offer the best protection against the risk of disease.
What must optimal nutrition provide?
- Must be enough nutrition to prevent deficient symptoms
- Something that optimises body stores (so we have plenty of vitamins and minerals that we need until we can eat again)
- Optimises some biochemical/physiological function
- Optimises a risk factor for some chronic disease - so minimising risk factor for chronic disease
- Minimises the incidence of a disease
Nutrient requirements are different in what factors/groups of people?
- Age - from birth to adulthood our nutrient requirements increase because we’re continuing to grow and develop. Hence we take in more energy more proteins etc until we reach adulthood. And as we become older (elderly) our nutrient requirements begin to decrease. This is because we exercise less and use as much energy as we used to.
- Gender - Males tend to have higher nutrient requirement than females and this is because males have more muscle mass than females. More muscles mean you would require more proteins etc.
- Physiological State - For example being pregnant will increase nutrient requirement
- Genotype - Everyone has a different genotype and how we metabolise our nutrients will depend on enzymes. The way they are metabolised will determine how much nutrients we require.
- Environmental factors - For example if you smoke, your vitamin C requirements go up due to the pro-oxidants you find in smoke.
What are the nutrient requirements for infants?
Nutritional requirement for infants are very high as infants grow and develop very rapidly.
Department of health recommends we take breast milk for the first 6 months as breastfeeding is the best form of nutrition for infants. It provides all the nutrients that are required for the first 6 months of a baby’s life.
Breast milk and formula milk (modified cows milk) are both nutritionally complete for the first months of life. No difference.
Breast milk however is best as it provides secretory IgA antibodies that can paint the GI tract of a baby, so provide with protection.
Breast feeding for any amount of time is beneficial.
What does RDA stand for?
Recommended daily allowance or Recommended dietary allowance
What is weaning and why is it important?
At 6 months it is important that babies start to be weaned.
This is because breast milk/formula milk at this stage is not enough as babies have higher requirements for energy, vitamins and minerals.
So for growth and development, the nutrient requirements are no longer met by breast milk alone.
Recommend the introduction of variety of foods. So that babies can get used to different tastes etc.
Six months recommended by the department of health for introduction of solid foods.
FOODS TO AVOID DURING WEANING:
- Wheat, Gluten, Fish, Shellfish, Fruit juices, Soya, Eggs (before 6 months) - due to risks of the developing allergies to them and the immune system is not fully developed yet
- Salt, sugar, honey (before 1 years old)
- Take extra care with textures to avoid choking
What are the nutrient requirements for pre-school children?
Requirements vary according to size and growth of child.
Overall, energy, protein, vitamins and mineral requirements increase.
Important to introduce a varied diet.
Children have small appetites - so any foods that they eat need to be nutrient-dense (proteins, vitamins etc) foods.
Whole milk can be given up until 2 years of age and then they can move onto semi-skimmed milk or low fat milk etc.
COMMON PROBLEMS THAT OCCUR IN PRE-SCHOOL CHILDREN:
- Faddy eating - children like certain foods and want the same kinds of food all the time etc
- Toddler diarrhoea - Often due to infants putting things in their mouth off the ground for example.
- Constipation - This is the time where they’re starting potty training.
- Anaemia - If they’re not introduced to foods with iron in them then they’ll be at risk of having low iron causing anaemia.
- Dental caries - For example if people add fruit juices in bottles and give it to babies, their teeth can develop dental caries due to the acid and sweetness in these drinks
What are the nutrient requirements for school children?
Follow healthy eating guidelines
Varied diet with adequate energy and nutrients for various growth periods which are sometimes rapid during these years
Good supply of protein, calcium, iron, vitamins A and D particularly important.
School meals - (controversial)
Physical activity important
What are the nutrient requirements for adolescents?
Growth and development period - growth spurt (hence more requirement of protein and energy) occurs during adolescence
Peak bone mass occurs during adolescence so calcium and vitamin D requirements increase. This provides us with strength we need throughout life and avoid osteoporosis later on. Physical activity aids bone strength.
Energy and nutrient requirements in boys are greater than girls
Growth spurt begins around age 10 in girls (earlier puberty) and 12 in boys
Iron requirements increase in girls after onset of menstruation and continue to be higher through until menopause. They lose iron monthly through the menstrual cycle.
What are the nutrient requirements in adulthood?
Energy and nutrient requirements increase until 17 years and then do not change too much between the ages of 19 and 64 years.
Energy requirement does depend on how much physical activity we do.
What is the recommended daily alcohol intake?
No more than 14 units per week on a regular basis
Spread evenly over 3 or more days
Heavy drinking once or twice a week increases risk of death from longterm illness and accidents and injuries
Risk of developing cancers increases the more you drink on a regular basis.
Have several drink-free days per week to cut down.
What are the nutrient requirements for pregnant women?
Healthy, varied diet during preconception/pregnancy
Energy :
- Energy requirements only go up in the final trimester
- Small increase in proteins requirement due to developing of tissues
- For lactation (breastfeeding), there is a larger increase in proteins
- Avoid shark, swordfish and marlin and limit tuna.
Micronutrients:
- 400ug folic acid required a day during first trimester
- Iron rich foods necessary and possibly supplements needed, particularly in the last trimester where theres an increase in blood volume at that stage.
- Vitamin A supplements and liver and liver products should be AVOIDED
No alcohol, limit caffeine and stay active
What are the nutrient requirements for older adults/elderly?
Energy requirements decrease with age as we’re less active.
Requirements for other nutrients stay similar to adulthood
Malnutrition common problem in this age group:
- Inadequate intake of dietary energy = loss of body weight, depletion of body fat store and muscle wasting
- Nutrient deficiencies
- Widespread metabolic physiological and functional adaptations occur
What are vitamins?
Vitamins are organic compounds required small amounts for normal functioning of the body.
They are important because they cannot be synthesised by the body.
Benefits of fruits and vegetables are due to the biological effects of vitamins.
BNF:
In the BNF you will find vitamins used as prevention and treatment of deficiencies.
Vitamins are not prescribed via the NHS as just dietary supplements.
What are minerals and trace elements?
They are inorganic compounds required by the body.
Minerals are required more than 100mg a day. Examples include calcium, magnesium etc.
Trace elements and required less than 100mg a day. Examples include Iron, chromium, fluoride, zinc etc.
FUNCTIONS:
- Structural - bones and teeth formation and development e.g. Ca, Mg, P
- Components of biological fluids
- Nerves and muscles e.g. Ca
- Iron - required for oxygen carrying
- Osmotic balance - e.g. Na, Cl
- Enzymes e.g. Mn, Cu, Fe
- Hormones e.g. Iodine for thyroxine
How are vitamins involved in electrolyte absorption?
Most water-soluble vitamins (e.g. vitamins C and D) are absorbed PASSIVELY (without energy) expect:
- Vitamin B12, which requires intrinsic factor (produced in the stomach) for receptor-mediated endocytosis in the terminal ileum
- Fat-soluble vitamins are carried in micelles and absorbed passively with end products of fat digestion (mono-glycerols and fatty acids)
- Calcium and iron absorption is tightly regulated - as we don’t want to have too much free calcium or free iron as they can damage cells. Calcium is a very important second messenger hence needs to be tightly regulated.
- Other electrolytes - unregulated
What are the clinically relevant important micronutrients and why?
Required for Energy metabolism and co-factors in enzymes - All Vitamin Bs
Antioxidants - Vitamins A, C, E, Zn, Se
Bone (and other functions) - Vitamin D, Vitamin K, Ca, P, Mg
Iron - Carrying oxygen around the body
What is Iron and why is it essential?
Iron is very essential for any aerobes. Those that require oxygen for life.
FUNCTIONS:
- Iron in humans gets incorporated into haemoglobin, which is then carried around the body to where it’s required.
- Myoglobin - Iron is incorporated in myoglobin which is in the muscle
- Cytochrome P450s - Iron is incorporated in Cytochrome P450 which is important in transformation of xenobiotics and drug metabolism
- Catalase function
- Peroxidases
- Cell growth and differentiation
How is Iron metabolised?
Iron is metabolised in the body. It is very tightly regulated at the gut, we only absorb as much as we need.
The absorbed Iron will be transported around the body via transferrin. Transferrin will cary iron wherever it’s needed to, main place being the production of RBC precursors that’ll be required in the bone marrow. Circulating RBCs have a lot of iron within them due to its function in haemoglobin formation.
Stores are regulated by intestinal iron absorption.
How absorption of Iron regulated tightly in the body?
- Transport proteins are involved in absorbing iron from the lumen of the gut. Heme carrying protein 1 for heme irons (Fe2+) and divalent metal transporters 1 for non-heme iron (Fe3+).
- These will carry iron into the epithelial cells.
- Dietary iron that is absorbed into the small-intestine epithelial cells and is immediately NEEDED for RBC production is transferred inti the blood by the membrane iron transporter FERROPORTIN.
- In the blood, the absorbed iron is carried to the bone marrow bound to transferrin, a plasma protein carrier.
- Absorbed dietary iron that is NOT immediately needed is stored in the epithelial cells as FERRITIN, which cannot be transferred into the blood.
- This unused iron is lost in the faces as the ferritin-containing epithelial cells are disposed of/shed off.
- Dietary iron that was not absorbed is also lost in the faces.
What are the 2 different sources of Iron?
- Haem iron - Found in Red meat, fish and poultry
- Non-haem iron - Found in Plant food, e.g. lentils, beans iron-enriched / fortified foods
You can increase the absorption of non-haem iron by taking Vitamin C in the same meal. Vitamin C is an antioxidant, so it reduces the ferric iron (Fe3+) to the heme iron (Fe2+). Red meat and organic acids can also increase absorption of non-haem iron.
You can decrease the absorption of non-haem iron by phytates, tannins, calcium and soy.
What is iron deficiency?
Decreased iron in the body.
Negative iron balance develops into iron deficiency anaemia - Hb levels eventually drop after stores depleted.
Anaemia - Where you get these pale, hypochromic (pale blood cells), microcytic (small) RBC compared to normal.
- Commonly found in women of childbearing age or pregnant women. In premature infants, low weight bearing infants, older infants, toddlers and teenage girls.
- Also found in patients with kidney failure, chronic malabsorption (where they’re losing iron through the gut), GI diseases (e.g. leaky gut)
- Pallor (unhealthy pale appearance), tired and weak, poor work performance
- Slow cognitive and social development in childhood
- Vitamin A deficiency limits use of iron stores
Iron deficiency is also associated with a decreased in immunity.
Iron deficiency is also associated with heart failure if there is severe anaemia as theres not enough oxygen getting to the heart.
When are iron supplements required?
When diet cannot restore stores within reasonable time or clinical deficiency
Supplements to restore stores and then diet
SUPPLEMENTAL IRON:
- Ferrous salts
- Ferric iron
- Amount absorbed decreases with increasing doses, therefore 3 equally spread doses per day
Side effects:- GI, nausea, vomiting, constipation, diarrhoea etc (start with half dose)
Not recommended for those with normal iron stores because of iron overload and pro-oxidant effects
What is chronic iron toxicity?
Genetic diseases which cause iron overload:
- Thalassaemias - Large group of genetic disorders of globin chain synthesis where blood transfusions required often
- Haemochromatosis - Genetic iron storage disease - causing damage and inflammation in tissues
TREATMENT:
Iron chelators - E.g. Desferrioxamine - complex with ferric iron
Also desferiprone and deferisarox but more side effects
What are Nutraceuticals?
Food or ingredient that provides medical or health benefits, including prevention and treatment of disease.
Includes dietary supplements and functional foods.
