Module 3 WK7+8 Flashcards
M3 T1,2 - introduction to micronutrients + fat soluble vitamins
What is meant by nutrient density? How can the nutrient density of a food be evaluated?
Nutrient density refers to the concentration of nutrients (micronutrients with NRVs and protein primarily) of foods relative to the RDI /AI for the selected nutrients and relative to the energy content (kJoules) of the food for a set reference weight of food (e.g. 100 grams /mL, 1 gram/mL, 1 serve etc.), or amount of kilojoules from that food.
Different foods can be compared using these parameters.
E.g.:- 100 g of food A provide “x” kJoules and “a” % of the RDI for nutrients c, d and e whilst 100 g of food B provide “y” kJoules and “b” % of the RDI for nutrients c, d, and e
What are some examples of:
- nutrient dense /energy poor foods:
seeds
spinach, blueberries, carrots
What are some examples of:
- nutrient dense /energy dense foods:
full-cream milk, almonds, sunflower
What are some examples of:
- nutrient poor energy dense foods:
soft drink, lollies, chips
One serve of cooked chicken thigh (80 g) provides 586 kJ, 19.4 g protein and 0.72 mg iron. One serve of peanut butter (30 g) provides 790 kJ, 7.3 g protein and 0.52 mg iron.
- Which is more energy dense?
- Which is more nutrient dense?
- Explain your answers
Which is more energy dense?
1 g cooked chicken = 7.3 kJ; 0.24 g protein; 0.009 mg iron
1 g peanut butter = 26.3 kJ; 0.24 g protein; 0.01 mg iron
* Which is more nutrient dense?
- 1 g cooked chicken = 7.3 kJ; 0.24 g protein; 0.009 mg iron
- 1 g peanut butter = 26.3 kJ; 0.24 g protein; 0.01 mg iron
Or you could calculate the % of the RDI for protein and iron per 100 kJ
Describe the Nutrient Profile Scoring Criterion. How does it work and why is it used?
The NPSC is a nutrient profiling system used in Australia and New Zealand to determine whether a food is suitable to make a health claim, based on its nutrient profile.
“A score is determined based on the amount in that food of energy, saturated fat, total sugars and sodium in the food, along with the amount of fruit, vegetables, nuts, legumes, coconut, spices, herbs, fungi, algae and seeds and in some cases, dietary fibre and protein”
The NPSC is primarily concerned to ensure that foods with a health claim don’t contain too much energy, saturated fat, sugar and sodium per 100g /100mL .
Only foods that meet a certain score will be allowed to have health claims made about them on the packaging.
This prevents foods with an unfavourable nutrient profile from making health claims.
Define “essentiality” in regards to micronutrients
for both vitamins and minerals: status of essentiality is based on the reliance on the diet to ensure supply. It is demonstrated by the presence of specific symptoms in deficiency, which are reversed when the nutrient is introduced or increased in the diet or supplemented. Does not mean supplement required systematically, more is not necessarily better
Outline the main difference between water and fat-soluble vitamins in terms of digestion, absorption
and toxicity
Digestion: Water-soluble vitamins are absorbed directly into the bloodstream; fat-soluble vitamins require bile and are absorbed with dietary fats.
Absorption: Water-soluble vitamins are easily absorbed; fat-soluble vitamins need dietary fat for absorption.
Transport and Storage: Water-soluble vitamins circulate freely in the blood and are not stored in large amounts; fat-soluble vitamins are stored in the liver and fat tissues.
Toxicity: Water-soluble vitamins generally have a low toxicity risk due to excretion in urine; fat-soluble vitamins have a higher toxicity risk due to storage in the body.
Describe food fortification in Australia: how it takes place, the purpose and the regulation in place
Mandatory fortification: food manufacturers must add specific micronutrients to specific foods, to address significant public health needs
e.g. thiamin and folic acid to flour in bread, iodised salt in bread, vitamin D to margarines and spreads
voluntary fortification: food manufacturers are allowed, under specific regulations (FSANZ code), to add selected micronutrients to “enhance” their product
e.g. iron in cereal, calcium in orange juice, n-3 polyunsaturated fatty acids in margarine
must conform with regulations regarding:
- quantity of added micronutrient: ratio of NRV, not above upper limit per serve
- form of micronutrient
- related claims that can be made on the packaging
- meeting nutrient profiling scoring criterion (NPSC)
Describe the types of claims that cam be made on food packaging? What is the general regulation for
these claims?
Nutrient content claims: about the content of certain nutrients or substances in a food, such as “low in fat” or “good source of calcium” Claims need to contain at least the amount of calcium specified in the standard
health claims: about the relationship between food and health effects. must be supported by scientific evidence. Only permitted on foods that meet NPSC
e.g. standard doesnt allow health claims on foods higher in saturated fats, sugar or salt
2 types of health claims:
1. general level: about a nutrient/ substance in a food, and its effect on health, e.g. “calcium for healthy bones and teeth” based on 1 of the more than 200 pre-approved health relationships or a food-health relationship self-substantiated by the food business - FSANZ method + notification
- high-level claims: nutrient/ substance in a food and its relationship to a serious disease or biomarker, e.g. “diets high in calcium may reduce risk of osteoporosis in people 65years and over” “phytosterols may reduce blood cholesterol”
must be based on pre-approved food-health relationship
What are the factors that may reduce the concentration of minerals in crops?
- mineral concentration in the soil may vary, therefore affecting animal feed, and plant and animal food products concentration
- processing of grains - milling reduces mineral concentration in food products
What are the factors interfering with the availability of minerals for absorption?
excess fibre consumption
- fibre itself + phytic acid in fibre binds to minerals resulting in excretion (natural bakers yeast and sourdough contain phytase that free minerals, increasing bioavailability)
excess of some fruit and veg consumption
- some contain oxalic acid: binds minerals, reducing bioavailability e.g. Calcium in spinach is 5% absorbed vs 32% from dairy
polyphenols and tannins
- tea, red wine, dark chocolate decrease absorption of iron and calcium
consuming minerals of same valence at once
- competition for absorption - Zn2+, Fe2+, Ca2+ decrease absorption of each when consumed together (supplements)
What are the factors enhancing the availability of minerals for absorption?
Vitamins C: improves absorption of minerals, in particular non-heme iron absorption in same meal, by reducing it to ferrous iron (absorption form)
Good gastric HCl production:
- allows good digestion of protein foods: freeing minerals for absorption
- assists in converting minerals from 3+ to 2+ (therefore antacid medications impair bioavailability of minerals by reducing stomach acidity)
Poor mineral status
- absorption of minerals increases when needs are greater
small summary of preformed and provitamin A
Provitamin A includes certain carotenoids, while preformed vitamin A includes retinoids.
provitamin A -> plant-based foods, needs to be converted to its active form in the body
preformed V A -> animal-based foods, already in active form
What is the mechanism by which vitamin A deficiency leads to blindness?
Vitamin A deficiency leads to a decrease in the production of rhodopsin in the retina, leading to night blindness and ultimately to irreversible blindness.
Why are children with vitamin A deficiency more susceptible to infections?
Retinoic acid is involved in cellular differentiation, which helps maintain epithelial barriers that protect the body against the entry of pathogens.
vitamin A toxicity
From retinoids:
- Acute: GIT upset/ nausea; muscular incoordination, headaches
- Chronic: liver damage, hemorrhages, dry skin and mucous membrane, hair
oss, bone loss, coma, death
- Teratogenic: if the pregnant woman consumes large amounts => fetal malformation, spontaneous abortion
risks
From b-carotene:
- Carotenoids are converted to retinoids only when required
- Hypercarotenosis (orange discoloration of skin) but does
not cause liver damage and other retinoids toxicity symptoms
Why would increasing intake of spinach, kale, and other leafy greens slow the progression of age-related macular degeneration?
These foods are rich in lutein and zeaxanthin, which absorb blue light and act as antioxidants in the macula.
Samara knows that she can get vitamin D from the sun. How do you explain this to her?
Sun rays directly convert cholesterol in the skin to vitamin D3.
Samara’s doctor informs her that vitamin D is important for bone health. How do you explain the mechanism behind this?
Vitamin D promotes the expression of calcium transporters in enterocytes, leading to increased calcium absorption.
A drop in blood calcium levels triggers the release of parathyroid hormone. What effect does this have on vitamin D?
Parathyroid hormone promotes the conversion of 25-hydroxyvitamin D3 to 1,25-dihydroxyvitamin D3 in the kidneys
Vitamin D toxicity
- Most likely of all vitamins to cause toxicity
- Does not occur from sunlight or dietary sources but with supplementation overuse.
Supplement dosages can override regulatory processes - UL (80 µg or 3200IU) based on studies
assessing effect of vitamin D on blood calcium levels - Above UL: can cause over absorption of calcium and thus hypercalcaemia, with calcium deposit in kidney, joints, blood vessels, heart
- Vitamin D excess can also lead to bone demineralisation (via too much bone resorption) => review diagram on role of vitamin D on bone calcium
Which form of vitamin E does Bryn’s supplement contain?
All stereoisomers of α-tocopherol
Which mechanism has been proposed
to explain the link between vitamin E and chronic diseases prevention?
Vitamin E’s antioxidant properties, which can protect against oxidative damage to cells and DNA.
(while taking vitamin E supplements) Bryn accidentally got a paper cut which took more than 20 minutes to stop bleeding. Which mechanism best explains why it took so long to stop bleeding?
High doses of vitamin E interferes with vitamin K-dependent gamma-glutamyl carboxylase activity in the coagulation cascade
Which form of vitamin K is found in green leafy vegetables?
Phylloquinone
What is the role of vitamin K in blood clotting?
It is a coenzyme in the gamma carboxylation clotting factors
What is the mechanism of action of warfarin?
It inhibits the activity of reductase enzymes involved in vitamin K reactivation
While taking warfarin, which vitamins should Tom avoid supplementing with?
Vitamin A because high doses can interfere with vitamin K absorption
Vitamin E because high doses can increase the activity of warfarin
what best describes minerals
inorganic elements
what best describes trace minerals
needed at less than 100mg per day
in what form are minerals absorbed
2+ valence form
how do minerals travel in the blood
bound to proteins
how are minerals excreted from the body
through the urine
what effects mineral concentration in foods?
soil quality
what effect does milling have in the mineral content in grains?
it reduces mineral content
Why is it hard to make blanket statements about the benefits of multivitamins?
There is no standard regulatory definition of what nutrients or to what level a multivitamin must contain
Formulations can be targeted at different population groups
Definitions of multivitamins are broad and can include additional herbal ingredients
What did the Women’s Health Initiative study find about the link between taking multivitamin supplements and developing cancer, cardiovascular disease, or dying earlier?
there was no significant link
What did The Physicians Health Study II find regarding the benefit of multivitamins?
There was a lower risk of developing cancer, but there was no significant reduction in the risk of mortality from cancer.
Which group of people are more likely to take multivitamins?
People with higher incomes
What is one reason people who take multivitamins tend to have better health?
People who take multivitamins tend to have healthier diets and lifestyles
what are the fat soluble vitamins
Vitamin A
Vitamin D
Vitamin E
Vitamin K
How are retinyl esters and carotenoids released from protein in food during digestion?
through the activity of proteases
During digestion, retinyl esters are hydrolyzed to retinol and fatty acids. How does this occur?
through the activity of lipases, hydrolases and esterases
What percentage of carotenoids is absorbed from raw vegetables?
5%
What percentage of retinol is absorbed if at least 10 grams of fat is present in the meal?
70-90%
What is the main form of vitamin A stored in the liver?
retinyl esters
Where are carotenoids stored in the body?
liver, adipose tissue, and eye
How is retinol transported in the circulation?
Bound to a complex of retinol binding protein and transthyretin
How are carotenoids transported in the circulation?
in lipoproteins
how does vitamin A affect gene expression
Vitamin A can activate gene expression by binding to nuclear receptors.
Which carotenoids absorb blue light to prevent age-related macular degeneration?
Lutein and zeaxanthin
what are rich sources of preformed Vitamin A
milk, liver!!, herring, fish
rich sources of provitamin A
sweet potato, spinach, carrots, kale
What is the term used to describe the goose bump-like appearance resulting from vitamin A deficiency?
Follicular hyperkeratosis
what symptoms are a result of chronic retinoid toxicity?
Liver damage and bone loss
describe the role of vitamin A in the visual cycle
11-cis retinal attached to opsin to form rhodopsin, light hits the retina on the back of the eye, rhodopsin absorbs light and 11-cis retinal is converted to all-trans retinal, all-trans retinal separates from opsin and opsin triggers a cascade of changes that sends a signal to the brain, all-trans retinal is enzymatically converted back to 11-cis retinal, opsin and 11-cis retinal are enzymatically combined to regenerate rhodopsin
Is it possible to reach the UL for vitamin A through carrots?
no, The upper level (UL) applies to retinol only. There is no UL for provitamin A carotenoids (as found in carrots) as their conversion to retinoids in the body is regulated by vitamin A status.
what is the active form of vitamin D and how is it synthesised
Calcitriol, also known as 1,25-dihydroxycholecalciferol, is the active form of vitamin D in the body. It is synthesized endogenously from precursors in a series of steps that occur in the skin, liver, and kidneys.
The first step in the synthesis of calcitriol begins in the skin, where 7-dehydrocholesterol is converted into cholecalciferol (vitamin D3) upon exposure to UVB radiation in sunlight. Alternatively, vitamin D3 can be obtained from dietary sources or supplements.
The first step in the synthesis of calcitriol begins in the skin, where 7-dehydrocholesterol is converted into cholecalciferol (vitamin D3) upon exposure to UVB radiation in sunlight. Alternatively, vitamin D3 can be obtained from dietary sources or supplements.
Once formed, cholecalciferol is transported to the liver, where it undergoes hydroxylation to form 25-hydroxycholecalciferol (calcidiol), the major circulating form of vitamin D in the body.
Calcidiol is then transported to the kidneys, where it undergoes further hydroxylation to form 1,25-dihydroxycholecalciferol (calcitriol). The synthesis of calcitriol is tightly regulated by parathyroid hormone and calcium ion concentrations in the body.
Overall, the endogenous synthesis of calcitriol is an important process that helps to maintain calcium and phosphate homeostasis, as well as support a variety of other biological functions, including bone health, immune function, and cellular differentiation.
What is the main difference between vitamin D2 (ergocalciferol) and vitamin D3 (cholecalciferol)?
Vitamin D3 is the form of vitamin D found in animal products, while vitamin D2 is found in mushrooms and fortified foods.
How is endogenously synthesized vitamin D3 transported in the blood?
Bound to vitamin D binding protein or albumin
How does vitamin D promote renal calcium reabsorption?
By directly stimulating calcium reabsorption in the kidneys
Which of the following describes the mechanism by which vitamin D promotes calcium absorption in the small intestine?
Vitamin D increases expression of calcium transporters in enterocytes
interaction between vitamin D and parathyroid hormone (PTH) in calcium homeostasis?
Vitamin D and PTH both promote bone resorption
A condition caused by vitamin D deficiency in childhood characterised by bowed legs.
Rickets
Which of the following is a consequence of vitamin D toxicity on calcium homeostasis?
Bone demineralisation due to excessive bone resorption
Why do vitamin D requirements increase with age?
Because the skin’s ability to produce vitamin D decreases with age
What is the primary function of vitamin E?
To act as an antioxidant
What is the most biologically active form of vitamin E?
Alpha-tocopherol
main food source of vitamin E?
Nuts and seeds
Which part of grains is a good source of vitamin E?
Germ
What is the potential risk associated with high doses of vitamin E supplementation?
High doses of vitamin E supplementation increase the risk of bleeding/ hemorrhaging by interfering with vitamin K activity.
What medication should be avoided when taking vitamin E supplements?
Warfarin
What condition is associated with vitamin E deficiency?
Hemolysis of red blood cells
What is the adequate intake (AI) for vitamin E expressed as?
Alpha-tocopherol equivalents
What is another name for vitamin K1?
Phylloquinone
What is the family name for vitamin K2?
Menaquinones
In which type of food is vitamin K1 mainly found?
Green leafy vegetables
How is vitamin K2 produced?
By bacteria in fermented and animal foods and in our gut
What is the active form of vitamin K needed for gamma-carboxylation of glutamic acid residues?
Dihydroquinone
What is the function of vitamin K-dependent gamma-carboxylation of glutamic acid residues?
To allow calcium ions to bind
What is the function of vitamin K in the coagulation cascade?
To activate clotting factors
What is the function of vitamin K in bone health?
To bind calcium in bone
Which vitamin interferes with vitamin K absorption when taken in high doses?
Vitamin A
Which vitamin interferes with vitamin K carboxylase activity in the coagulation cascade when taken in high doses?
Vitamin E
What is the consequence of vitamin K deficiency?
Increased risk of bleeding and hemorrhaging
