Overview of Minerals & Calcium

MINERAL OVERVIEW

what are the major elements (5)

oxygen, carbon, hydrogen, nitrogen, sulfur

what are the main categories for minerals? (5)

major/macro, trace, possibly essential, probable contaminants, toxic

2 MAIN categories?

major and trace minerals 

what are the essential major/macro minerals?

 calcium, phosphorus, potassium, sodium, chloride, magnesium.

Essential Minerals require intake of at least

> 100 mg/day

what are the Essential Trace Minerals (9)

Fe, Zn, selenium, manganese, Cu, iodine, molybdenum, cobalt (as B12), chromium

essential trace minerals are needed in how much?

required intake < 100 mg/day

Possibly Essential Trace Minerals (7)

boron, fluoride, nickel, silicon, tin, vanadium, arsenic

Probable Contaminants (6)

aluminum, antimony, bismuth, bromine, lithium, silver

Toxic Elements (3)

cadmium, lead, mercury

minerals can come from (3- not food)

from soils, water, and air

minerals are incorporated into __________, then _____________, and are widely distributed in ________________________________________________

incorporated into plants, then animals, and are widely distributed in whole grains, fruits and vegetables, meat and seafood

individuals on low-calorie diets may rely more on what to meet requirements?

on processing and fortification to meet requirements

Absorption of minerals occurs through what organ

intestine

absorption of minerals is mediated by 

mediated by carrier proteins

absorption of minerals is enhanced or inhibited by

composition of diet

absorption of minerals is also affected by

individual and dietary factors

individual factors are _____________ (ex/intrinsic)

intrinsic

dietary factors are _____________ (ex/intrinsic)

extrinsic  

Individual Factors are (extrinsic/intrinsic?)

Intrinsic factors which influence mineral bioavailability

Individual Factors examples: (10)

-Nutritional status

-General Health

-Growth

-Pregnancy

-Lactation

-Age

-Physical activity

-Diseases

-Genetic factors

-Inborn errors of metabolism

Dietary Factors are (extrinsic/intrinsic?)

Extrinsic factors that affect bioavailability

extrinsic factors refer to those

we do not control (the chemical process, interactions, comp)

Dietary Factors examples (6)

-presence in foods

-chemical composition

-other minerals

-other nutrients

-other non-nutrients

-processing

CALCIUM

Calcium is the....

5th most abundant element in the human body

What percentage of calcium is found in hard tissue such as bone and teeth?

99%

What percentage of calcium is distributed intra- and extracellularly?

1%

What is the reserve site for calcium in the body?

Bone

What percentage of body weight does calcium represent in the body?

1-2%

primary sources of Ca (food)

Dairy products

calcium also found in 

fish with bones (sardines), fruits and vegetables, nuts, seeds, and legumes

Fortified sources of calcium include

grain products and juices

Some vegetables are good or bad sources?

poor sources

what do some vegetables have that makes them a bad source of Ca?

oxalic acid (inhibit)

Meat and non-fortified grains are good or bad sources?

poor sources

Supplements forms include (6)

carbonate, citrate, lactate, gluconate, acetate, monophosphate

what forms of calcium are predominant in supplements (2)

citrate and gluconate are predominant

Ca ingested as

insoluble salts

If solubilized, calcium can

can bind to other compounds

Average absorption in adults

~25-30%

Paracellular diffusion occurs at what %

~5-20%

Paracellular diffusion of calcium occurs where? 

throughout the intestine, but mostly in jejunum and illeum

what does paracellular mean?

between the cells; so does not go from the lumen—> intestinal cell—> blood, but goes between them to get to the blood

what influences rate of paracellular diffusion of calcium

dietary factor influence rate

How much of calcium is absorbed through active transport? and where?

~80-95% (duodenum and jejunum)

for active transport, Ca binding relies on

a calcium binding protein

Calcium active transport is regulated by ___________, stimulated by _________ & ___________

regulated by calcitriol

stimulated by calcitriol & low-calcium diets

for active transport of calcium, what receptor/transporters does it use to enter enterocyte?

transient receptor potential vallinoid (TRPV6) or calcium transporter 1

transient receptor potential vallinoid (TRPV6) is what type fo receptor?

cellular receptor 

in the enterocyte cytosol, what protein is needed to carry calcium?

vit D dependent calbindin

how is calcium released from the intestinal cell (lumen) into the plasma?

utilizing the vitamin D dependent calcium ATPase pump

where in the cell is Vit D dependent calcium ATPase pump found?

basolateral membrane 

___ and ___ decline during aging resulting in ______ need and recommendation

TRPV6 & calbindin

higher calcium

step 1 of Ca absorption: Ca2+ crosses the ____ of the enterocyte through ___________

Brush border membrane

Ca channel TRPV6

step 2 of Ca absorption: Ca2+ binds to _____, which carries the Ca across the ______

Calbindin D; cytosol

step 3 of Ca absorption: _____ or a ______ pump Ca across the basolateral membrane for entrance into the ____

Ca2+-ATPase (PMCA1b) or a Na+/Ca2+ exchanger (NCX1)

blood

step 4 of Ca absorption: Some Ca2+ is _______, typically w/ ___ Ca2+ concentrations in the _____

absorbed between cells (paracellular diffusion)

high

lumen

in the blood, what are the 3 forms of calcium that can be found?

• Free calcium

• Protein bound

• Nonprotein complexed calcium

what can inhibit calcium absorption?

• Phytic acid

• Oxalic acid

• Divalent cations

• Unabsorbed FA

what is another mechanism of transport calcium can have?

vesicular transport 

what do we mean by vesicular Transport

Endocytosis of Ca & vesicles formation.

what is used for vesicular transport of Ca?

vit D dependent rapid response steroid binding protein (MARRS)

what do rapid response steroid binding protein (MARRS) do?

facilitates calcium transport from the basolateral membrane

In the large intestine what can occur

bacteria may release bound calcium from fermentable fibers for colonic absorption

so absorption can also occur in the

colon (but amount is unknown)

what nutrients/substances enhance Ca absorption (3)

vit D (through Calbindin and MARRS)

Sugar & sugar alcohols

Protein

nutrients/substances inhibiting Ca absorption (5)

oxalic acid

Phytic acid

fiber

Excessive divalent cations (Zn & Mg)

unabsorbed FA

Nutrients enhancing urinary Ca excretion (3)

Na

Protein (mainly animal protein)

Caffeine

Nutrients in which absorption may be inhibited by excessive Ca (3)

Phosphorus

Fe

FAs

from intake of 600-800mg of dietary Ca, about __% is absorbed into plasma

30%

from intake of 600-800mg of dietary Ca, about __% is absorbed into fecal (unabsorbed)

70%

biggest route of excretion of calcium is

fecal

how much of calcium is excreted through urine 

about 200mg (small amount)

so calcium absorption and retention is 

LOW 

From plasma Ca (calcium absorbed), what can occur to it? (4 options)

- non-diffusible: protein bound

- Diffusible: ionized (free)

- Complex

- Urinary Ca

Ca Transport occurs through which 3 methods? (how can calcium be found in the plasma)

• binding to proteins (albumin, prealbumin)

• complexed w/ sulfate

• free form 

Regulation of calcium concentrations is based on ______________

extracellular calcium concentration regulation

extracellular calcium concentration regulation uses what? (3)

PTH, Calcitriol, Calcitonin

intracellular calcium concentration regulation refers to

calmodulin

Serum Total Calcium (what is the ideal amount)

8.5-10.5 mg/dL, 10 mg/dL (ideal)

what are the primary regulatory hormones for calcium?

PTH and calcitonin

ionized calcium is critical for 

the control of neuromuscular excitability

also in blood clotting factor activation  

Decreased Calcium levels may cause .... (3)

irritability, seizures, and cardiac problems

calcium in blood

• % as Ca2+ (pre-calcium)

• % as complexed Ca

• % as protein bound

• 47.5% as Ca2+

• 6.5% as complexed Ca

• 46% as protein bound

Low blood Ca levels signals what to do what?

Parathyroid Gland to release PTH into blood

once PTH is released into the blood, what does it do (2)

it binds to bone cell receptors & triggers resorption of bone to release Ca into blood

it goes to kidney to trigger synthesis of 1-hydroxylase for calcitriol synthesis 

mobilization of calcium in bone means what?

bone moving out of the bone and into the blood (when calcium levels are low) 

PTH and calcitriol promote

the reabsorption of calcium from the kidneys into the blood

calcitriol made in the kidneys then can do what?

goes to intestines to trigger absorption of calcium across brush border in the SI through calbindin

Ca enters blood from what 3 things

• release from bone

• release from kidneys

• absorption from intestinal cells

Hypercalcemia causes what (to regulate levels)-4

•Decreased Ca mobilization from bone

•Increased Calcitonin release to shuttle Ca to skeletal tissue for storage

•Increased renal excretion & decreased reabsorption

•Slows intestinal Ca absorption

when we have hypercalcemia, what is decreases? (bone)

calcium mobilization from bone

when we have hypercalcemia, what occurs in skeletal tissue

Increased calcitonin release to shuttle calcium to skeletal tissue for storage

when we have hypercalcemia, what occurs in the kidneys?

Increased renal excretion and decreased reabsorption

when we have hypercalcemia, what occurs in the intestines?

slowed intestinal absorption of calcium

Intracellular Calcium is ______% compared to extracellular

0.01%

intracellular calcium regulation involves

Cell activation via depolarization, neurotransmitter, and hormones that results in Ca movement into the cell

Channels used in intracellular Ca regulation

voltage gates, ligand gates, and stretch activated