Chapter 10-12: Water, Electrolytes, Minerals, Trace Elements Flashcards
What are some consequences of dehydration?
- headache
- fatigue
- dry mouth & eyes
- dark-coloured urine
More serious…. - nausea
- confusion
- disorientation
- death (10-20% loss)
What are some examples of electrolytes?
1) Sodium
2) Potassium
3) Chloride
What is hyponatremia?
- water intoxication
- excessive intake of water during prolonged exercise (low blood sodium)
- water moves out of blood into tissue –> swelling & damage to organs
- early symptoms are similar to dehydration
How are Canadians doing with respect to their intake of sodium and potassium from food?
1) too much sodium
2) not enough potassium
ns potassium intake may or may not be adequate
What effect does processing have on sodium and potassium contents of food?
1) Less processed: same amount of potassium, less sodium
2) More processed: potassium amounts do not change much, sodium levels skyrocket
What is a cation?
an ion with fewer electrons than protons (i.e. positively-charged)
- potassium = the major cation in the cell
- sodium = major cation outside of the cell
What maintains the balance between potassium and sodium in and around the cell?
Na-K-ATPase pump (sodium-potassium-ATPase pump)
What is the difference between interstitial & intracellular fluid?
- interstitial fluid = extracellular fluid (outside of the cell)
- intracellular fluid = cystol (inside the cell)
What is one of the main functions of electrolytes?
Regulation of blood pressure
- release of aldosterone from adrenal glands increases sodium reabsorption by the kidneys –> water follows the sodium, helping to maintain blood volume & blood pressure
What is hypertension?
Chronically (persistently) high blood pressure
- due to salt sensitivity –> slow sodium secretion + sodium causes constriction of blood vessels –> high blood pressure persists
What is the big contention surrounding sodium intake?
years of warnings to cut sodium consumption to reduce heart attack & stroke, but there is little evidence supporting that such reductions would actually be beneficial
- emerging evidence that sodium levels that are too low can be harmful
Is there a U-shaped curve for sodium?
Yes RDA = 1500mg UL = 2300mg AI = 500mg *however, there is no evidence for an additional benefit to lowering from 2300mg to 1500mg
What is the health claim on labels associated with potassium & sodium?
“A healthy diet high in potassium and low in sodium reduces the risk of high blood pressure, which is a risk factor for stroke and heart disease”
Diets high in potassium can counterbalance the effects of ____.
sodium
Which has the most potassium: banana, baked potato, or orange juice?
Baked potato has the most, followed by banana, then orange juice.
What are the complications of pregnancy related to electrolytes?
1) Gestational hypertension
2) Pre-eclampsia (high blood pressure, fluid retention, rapid weight gain)
3) Eclampsia (seizures, death)
What is the DASH eating plan?
A diet plan for reducing blood pressure
- similar to Canada’s Food Guide
- high in foods that contain potassium, calcium & magnesium
What is the health impact of combining the DASH plan with reductions in sodium?
DASH plan + low sodium –> reduced blood pressure more than low sodium or DASH on its own
- decrease in sodium lowered blood pressure more in control diet than in DASH diet group (maybe b/c blood pressure was already lower in DASH diet?)
What are minerals?
Inorganic elements needed by the body in small amounts
What are the 7 major minerals?
1) Sodium (Na)
2) Magnesium (Mg)
3) Potassium (K)
4) Calcium (Ca)
5) Phosphorous (P)
6) Sulfur (S)
7) Chlorine (Cl)
What are the trace minerals?
1) Lithium (Li)
2) Rubidium (Rb)
3) Vanadium (V)
4) Chromium (Cr)
5) Manganese (Mn)
6) Iron (Fe)
7) Molybdenum (Mo)
8) Nickel (Ni)
9) Copper (Cu)
10) Zinc (Zn)
11) Cadmium (Cd)
12) Boron (B)
13) Aluminum (Al)
14) Silicon (Si)
15) Germanium (Ge)
16) Arsenic (As)
17) Selenium (Se)
18) Bromine (Br)
19) Tin (Sn)
20) Lead (Pb)
21) Iodine (I)
22) Fluorine (F)
How are minerals consumed in the Canadian diet?
1) Natural sources
2) Fortified foods (i.e. iron, calcium, iodine)
3) Natural health products (ex. supplements; calcium for older women)
What are phytates, oxalates, and tannins?
- compounds that decrease absorption of minerals by binding them
1) Phytate –> grains (calcium, zinc, iron, magnesium)
2) Oxalate –> spinach & other veggies (calcium, iron)
3) Tannins –> tea & coffee (calcium, iron)
How does the absorption (bioavailability) of iron & calcium compare with that of sodium?
- sodium has 100% absorption
- iron & calcium have low absorption/bioavailability
How are Canadians doing with respect to their intake of calcium from food & supplements?
- high prevalence of inadequate intake across the board
How are Canadians doing with respect to intake of magnesium & phosphorous in food?
- high prevalence of inadequate intake of magnesium
- low prevalence of inadequate intake of phosphorous
What are minerals as cofactors?
- many minerals serve as cofactors (make the enzyme active)
- ex. selenium is a cofactor for an antioxidant enzyme system
- mineral cofactor combines w. incomplete enzyme to form active enzyme
What is the main purpose of calcium?
Bone structure & health
- calcium levels in the blood must be maintained in a very narrow range
What happens when calcium blood levels are low? What may this lead to over time?
calcium is taken from bone
- may lead to osteoporosis over a lifetime
How is calcium absorbed?
1) Vitamin D promotes synthesis of calcium transport proteins
2) Calcium is carried across the enterocyte
3) Calcium pump (that req’s energy) moves into the blood
How does calcium absorption differ across age groups?
Infants –> 60% absorption
Adults –> 25-30%
Adults w. vitamin D deficiency –> as low as 10%
During pregnancy –> absorption increases (so RDA for calcium in pregnancy is unchanged)
RDA of calcium takes into account the _____.
low absorption rate
- body needs 300mg/day to meet needs, so RDA = 1,000mg
How is bioavailability of calcium affected?
- decreased by tannins, fibre, phytates, oxalates
Vegetables low in oxalate are good sources of ____.
CALCIUM
- ex. kale, collard greens, chinese cabbage
How are Canadians doing with respect to their intake of calcium from food & supplements?
- high prevalence of inadequate intake across the board
How are Canadians doing with respect to intake of magnesium & phosphorous in food?
- high prevalence of inadequate intake of magnesium
- low prevalence of inadequate intake of phosphorous
What is the main purpose of calcium?
Bone structure & health
- calcium levels in the blood must be maintained in a very narrow range
What happens when calcium blood levels are low? What may this lead to over time?
calcium is taken from bone
- may lead to osteoporosis over a lifetime
How is calcium absorbed?
1) Vitamin D promotes synthesis of calcium transport proteins
2) Calcium is carried across the enterocyte
3) Calcium pump (that req’s energy) moves into the blood
How does calcium absorption differ across age groups?
Infants –> 60% absorption
Adults –> 25-30%
Adults w. vitamin D deficiency –> as low as 10%
During pregnancy –> absorption increases (so RDA for calcium in pregnancy is unchanged)
RDA of calcium takes into account the _____.
low absorption rate
- body needs 300mg/day to meet needs, so RDA = 1,000mg
How is bioavailability of calcium affected?
- decreased by tannins, fibre, phytates, oxalates
Which 2 glands are primarily involved in regulation of blood calcium levels?
1) Thyroid gland (when blood calcium = high) –> calcitonin (inhibits calcium release)
2) Parathyroid glands (when blood calcium = low) –> parathyroid hormone (activates vitamin D)
What processes are involved in increasing blood calcium when it is too low?
Parathyroid glands release parathyroid hormone…
i) activates vitamin D –> increases intestinal calcium absorption
ii) + vitamin D –> calcium reabsorbed by kidney
iii) + vitamin D –> stimulates release from bone
What are the non-bone related functions of calcium?
1) Muscle contraction
2) Neurotransmitter release
3) Blood clotting
4) Blood pressure regulation
What is the association between calcium & colon cancer in observational studies?
Inverse association
- hypothesized that calcium binds w. toxins in the colon making them insoluble & biologically inactive
What is the difference between trabecular bone and cortical bone?
- trabecular bone = spongy (inside cortical bone)
- cortical bone = compact (hard)
What is the mineral component of bone made of?
- mainly hydroxyapatite (calcium & phosphorous) –> inorganic matrix
- also, Ca5(PO4)3OH and collagen (protein; organic matrix)
What are the two main processes of bone remodelling?
Osteoclast –> bone resorption
Osteoblast –> bone formation
What is osteoporosis?
- loss of both protein (organic matrix) and inorganic matrix (mineral/hydroxyapatite) components from the bone
What does a T-score measure?
Bone mineral density as a measure of standard deviations from normal
What happens to the spine when weakened by osteoporosis?
- the front edge of the vertebrae collapses more than the back edge, so the spine ends bends forward (trabecular bone is crushed)
- leads to decline in height
What are the factors that affect the risk of osteoporosis?
Acronym: GARFBESAD
1) Gender (2x more likely in women)
2) Age (bone loss w. age)
3) Race (lower risk in blacks)
4) Family history
5) Body size (thin & light individuals have an increased risk b/c they have less bone mass)
6) Exercise (weight-baring exercise increases bone density)
7) Smoking (tobacco use weakens bones)
8) Alcohol abuse (long-term alcohol use interferes w. body’s ability to absorb calcium)
9) Diet (diet lacking in calcium & vit D –> increased risk, esp. during bone formation years)
What is accretion?
uptake & accumulation of calcium from the diet
Both men & women lose bone slowly after the age of ___.
35
During which stage in life does bone mass increase rapidly?
puberty
When is bone loss accelerated for just women?
for about 5 years after menopause
Estrogen stimulates ____ activity.
osteoblast
How does age-related bone loss occur?
- when osteoclast activity exceeds osteoblast activity
How can osteoporosis have an impact on your overall health?
More likely to fracture bones –> 3-4x more likely to die from this (directly or indirectly)
- immobility –> pneumonia –> death in 20% of hip fractures
- loss of muscle mass
- added stress
How can exercise help prevent osteoporosis?
- stress on bone stimulates mineralization
When does decline in milk consumption typically begin in Canada?
in adolescence and continues into adulthood
What is the relationship between calcium supplements and myocardial infarction?
Associated w. increased risk of myocardial infarction
- warrants a reassessment of the role of calcium supplements in management of osteoporosis
How common is a phosphorous deficiency?
very rare
What role does magnesium play in the body?
1) part of the inorganic matrix of bone
2) needed for vitamin D function
What is iron an essential component of?
the heme group
- sits inside the hemoglobin & myoglobin (proteins)
What is iron mainly used for in the body?
The binding of oxygen
- lungs –> oxygen binds to Hb in the blood –> delivers oxygen to tissue –> aerobic metabolism
What is the typical absorption rate of iron?
very poor (~5-15%)
What types of sources can iron come from?
1) Heme iron –> animal sources (myoglobin in meat); best absorbed
2) Non-heme iron –> plant sources (leafy green veggies, legumes, whole & enriched grains); more poorly absorbed than heme iron
3) Iron cookware –> acidic foods increase leaching (increase iron consumption w/out increasing calories)
How is iron absorbed?
- converted to ferric form (Fe+++) by copper-containing protein, then to ferrous form (Fe++), which is absorbable
- MFP (meat fish poultry) protein enhances absorption
What is in iron supplements?
ascorbic acid
What are ferritin & hemosiderin?
- storage proteins
- store iron if there is excess in the diet
What does transferrin do?
- binds iron in the blood
- transports iron to liver, bone, & other body cells
What is iron loss mostly due to?
blood loss
What does the body do with iron to avoid oxidative stress?
- iron is always bound to a protein
What is a transferrin receptor?
- on the cell membrane
- binds transferrin & brings it into the cell
What is free iron?
- iron not bound to a protein?
- Fenton reaction
[slide 58, ch. 12]
What is anemia?
- iron deficiency
- oxygen-carrying capacity of the blood is decreased b/c there is insufficient iron to make hemoglobin
- fatigue
What is catalase?
- an enzyme that converts hydrogen peroxide to water
Which two minerals compete for absorption?
1) calcium
2) iron
* therefore, a diet of high calcium intake interferes w. iron absorption
What are the iron requirements of an infant?
- born w. 6 month iron stores in liver
- exclusively breastfed babies should be supplemented w. iron b/w 4-6 months (breast milk doesn’t contain a lot of iron)
- after 6 months, iron-containing foods should be fed (ex. cereals, meats)
What are the two types of iron toxicity?
1) Acute - a single high dosage
2) Hemochromatosis (Iron overload) - iron accumulation –> tissue damage
- treated w. frequent blood donation
What does zinc deficiency look like?
- stunted growth & sexual development
- compromised immune system –> increased infections
- diets high in phytates & low in animal products (ex. unleavened breads are high in phytates)
What do high intakes of zinc stimulate?
the synthesis of metallothionein-protein (a protein that binds metals)
What role does zinc play in gene expression?
- Zinc “fingers” (binds DNA-binding protein receptor to DNA?)
[slide 69, ch. 12.3]
What functions does zinc aid in?
1) Gene expression
2) Component of many enzymes –> ex. superoxide dismutase prevents oxidative stress
3) Immune system –> zinc lozenges show modest improvements of cold symptoms
What is the relationship between zinc & copper?
1) High intake of zinc –> increased synthesis of metallothionein –> binds copper –> reduced copper absorption
2) Copper is req’d for the absorption of zinc
3) Copper is a co-factor with zinc in the enzyme superoxide dismutase
What is manganese?
component of superoxide dismutase
What is Keshan disease?
- a risk of selenium deficiency
- muscular discomfort, weakness
What are some of the symptoms of selenium toxicity?
- hair brittleness & loss
- nail brittleness & loss
Where is iodine found in the diet?
1) Seafood & plants grown near the sea
2) Iodized salt
Which hormone is iodine a component of?
Thyroid hormone
What do thyroid hormones do?
Regulate energy metabolism
- circulate in the blood bound to plasma proteins
- increases mRNA generation by binding to a regulatory region of a target gene –> increase in amount of protein synthesized by this cell
What are 2 instances of iodine deficiency?
1) Hypothyroidism –> reduced metabolic rate, fatigue, weight gain
2) Cretinism –> deficiency during pregnancy leaves infant w. developmental delay, deafness, growth failure
3) Goitre –> enlargement of thyroid gland
What is an important difference between table salt (used in the home) and the salt used in processed foods?
processed foods do not use iodized salt
What is the status of iodine in the Canadian diet? How is iodine status determined?
- adequate intake
- determined by measuring iodine excretion in urine
What function does chromium play in the body?
- enhances insulin function by activating a peptide that binds to the insulin receptor
(better glucose uptake)
What does fluoride do?
Reduces tooth decay
- strengthens bones (fluoroapatite)
