Benhälsa och vitaminer Flashcards
Major functions of bones - mekanisk
Mechanical Functions of bones:
Protection
Shape
Movement
Synthetic Functions of Bones:
Synthesis of blood cells (Hematopoietic stem cells or
hemocytoblasts are the stem cells that give rise to all the other blood cells
through the process of haematopoiesis. Located in the red bone marrow)
Metabolic Functions of Bones:
Mineral Storage
Fat storage
Role in acid-base balance (Bone buffers the blood against
excessive pH changes by absorbing or releasing alkaline salts)
Composition of bones-total
• 65-67% - minerals (mostly calcium and phosphorus)
• 33-35% - organic substances ((~90% type I collagen,
~5% noncollagenous proteins (NCPs), ~2% lipids by weight)
Composition of component in bone - minerals
- Hydroxyapatite (Ca10(PO4)6(OH)2)
- HA as has a Ca:P ratio of 5:3 (1.67)
Ca = 39% carbonate = 9,8% organiskt = 33%
Composition of organic component in bone
Collagen: 90% of organic component • primarily type I collagen • provides flexible strength Cytokine and growth factors • small amounts present in matrix • aid in bone cell differentiation, activation, growth, and turnover Matrix proteins • includes noncollagenous proteins • osteocalcin, osteonectin, osteopontin • promote mineralization and bone formation Proteoglycans • responsible for compressive strength • inhibit mineralization
Bone development and activity
bone growth
bone modeling
bone remodeling
bone growth
The size of bones increases. The first period of rapid bone growth is from birth to age 2, but growth continues in spurts throughout childhood and into adolescence.
bone modeling
Although our bones stop growing in length at 18 - 21 years, bones can increase in thickness if they are stressed by excessive or repetitive exercise such as weight training or by being overweight.
bone remodeling
Bone remodeling involves the removal of mineralized bone by osteoclasts followed by the formation of bone matrix through the osteoblasts that subsequently become mineralized.
Varför sker resorption?
The process of resorption exists for two reasons: 1. liberate calcium and other ions 2. clear out damaged pieces of the skeleton and promote the deposition of newer, better material.
Varför finns ben remodeling?
Bone Remodelling Maintains a Balance Between Breakdown and Repair!
How much calcium should we consume?
800mg/dag för vuxen
Adequate calcium intake is critical to achieving optimal peak bone mass and modifies the rate of bone loss during aging!
Calcium absorption - hur går det till
Transcellular, active mechanism that transports calcium when dietary calcium intake is normal/low and a paracellular, passive pathway that functions under high calcium intake
Varför är intagen av ca viktigt för benen?
När är det speciellt viktigt?
• An adequate calcium intake at all stages of
life (coupled with an active lifestyle) helps
to ensure that bones are as strong as
possible.
• It is particularly important during childhood,
adolescence and early adulthood when
bones are developing.
Varför är det inte bara bra med ca intake?
Calcium or dairy products do not have a clinically relevant
impact on bone health in youth.
Only less than 1/3 of all studies showed a benifit of
calcium or dairy products on bone health
What happened if we don’t consume enough calcium?
• There are no short-term symptoms associated with too little
calcium
• Long-term effect – osteoporosis
• Hypocalcemia – low levels of calcium in blood – is not due
to low dietary calcium, but to some kidney diseases,
vitamin D deficiency, low production of thyroid hormones
What happened if we consume too much calcium?
• No significant toxicity symptoms in healthy individuals
• Hypercalcemia – high levels of calcium in blood –
overproduction of thyroid hormones, cancer
Vad gör Phosphorus i benen?
• One of the primary roles of phosphorus is to provide
structure to our bones and teeth.
• About 85% of the phosphorus found in our bodies is
stored in our bones
• The remaning phosphorus is evenly distributed in all
tissues in form of phosphate
Hur mycket phosfor får vi i oss?
In human adults, under steady state conditions, a regular Western diet provides between 1000 and 1,600 mg/day (approx. 20 mg/kg/day) of phosphorus
How much phosphorus should we consume?
600mg/d
• In Sweden, intake of phosphorus is approximately 1200 - 1400 mg per day
• The bioavailability of phosphorus differs among food sources. Some forms of
dietary phosphorus are less bioavailable, especially the phosphorus in the
phytic acid found in the outer layer of cereal grains
Hur funkar inorganisk phosfate?
• Inorganic phosphate salts such as additives used in food processing are
readily hydrolysed in the gastrointestinal tract and absorbed
What happened if we don’t consume enough phosphorus?
• Never recorded amoung healthy
• Can occur in premature infants, in people who abuse
alcohol, in elderly with poor diets
What happened if we consume too much phosphorus?
- Muscle spasms and convultion
* In people who take too many vitamin D supplements
Magnesium
vad gör detta i benen?
One of the primary roles of magnesium is to provide
structure to our bones and teeth.
• About 50-60% of the magnesium found in our bodies is
stored in our bones
• Magnesium forms a surface constituent of the
hydroxyapatite (calcium phosphate) mineral component
• Magnesium regulates formation of hydroxyapatite
Magnesium absorption
Bulk Mg2+ is
absorbed paracellular
by the late part of the
small intestine.
∼30–50% is absorbed in the intestine • However, if Mg2+ intake is low, early reports suggest that up to 80% of dietary Mg2+ can be absorbed
How much magnesium should we consume?
280/350 mg/dag
What happened if we don’t consume enough magnesium?
• Hypomagnesemia (anorexia, vomiting, lethargy, weakness,
personality change)
• This condition can occur in elderly, people with chronic
diarrhea and chronic alcohol abusers
What happened if we consume too much magnesium?
• Excessive magnesium intake (0.5–5 g/d) gives diarrhea,
but otherwise no negative symptoms are observed when
kidney function is normal
Vitamin D - vad är detta, varför viktig för ben?
• Fat-soluble vitamin
• Vitamin D has an important role together with calcium in
mineral metabolism and bone growth and maintenance
Process of converting sunlight into vitamin D
The conversion of vitamin D to its active form occurs in the kidneys, but it can also occur in the skin, prostate, brain, pancreas, adipose tissue, skeletal muscle, heart, colon, monocyte/macrophages and in neoplastic tissues
Factors that inhibit synthesis of vitamin D:
Season (winter month) Age – older age Use of sunscreen Clothing or dark skin pigmentation Glass and plastics Obesity (negative impact on metabolism and storage of vitamin D)
What happened if we don’t consume enough Vit D?
• Loss of bone mass (if not enought Vit D, calcium
absorption decreases to 10-15%)
• Inadequate mineralization of the skeleton (rickets in
children, and osteomalacia in adults)
What happened if we consume too much Vit D?
• Cannot be too much from sun, because our skin limit Vit
D production
• Cannot be too much from food, because the levels of
vitamin D naturally found in food is low
• Only from supplementation. Might cause hypercalcemia
– high levels of calcium in blood
Osteoporosis - vad är dettta
• literally means “porous bones”
• bones lose an excessive amount of their protein
and mineral content, particularly calcium
• Bone become fragile and break easily
Osteoporosis: “a skeletal disorder characterized
by compromised bone strength predisposing a
person to an increased risk of fracture.
Osteoporosis vs osteomalacia
Osteoporosis
• decreased bone mass
with a normal ratio of
mineral to matrix.
Osteomalacia • ratio of mineral to matrix is decreased (ie there is too much matrix relative to the amount of bone)
Factors affecting bone mass
Non- or hardly modifiable • Gender • Age • Genetics • Ethnicity
Modifiable
• Hormonal status
(especially sex and
calciotropic hormone
status)
• Lifestyle factors
- Physical activity
- Alcohol consumption
- Smoking
• Nutrition
The integrity of the skeleton requires :
a dynamic balance between bone
formation and bone resorption.
If a dysfunction occurs in these two
processes, pathologies can develop.
Function of vitamin K
K1 – used mainly for blood clothing
K2 – important in non-coagulation actions -
as in metabolism and bone mineralization,
in cell growth, metabolism of blood vessel
walls cells.
osteocalcin
is a calciumbinding
protein synthesized by osteoblasts or bone-building
cells
Vitamin K and vitamin D
It also works synergistically with vitamin D to regulate
the production of osteoclasts, cells that remove old bone so
that new bone can be deposited in its place.
Var finns vitamin K
Leafy green vegetables, vegetable oils, and vegetable oil
based fat spreads are the main sources of phylloquinone
Menaquinones are found in liver, meat, egg yolk, and
dairy products
What happened if we don’t consume enough Vit K?
• Reduced ability to form blood clots, leading to excessive
bleeding
• No enought scientific evidence that vitamin K deficiency
leads to osteoporosis
What happened if we consume too much Vit K?
• Today no side effects associated with overconsumption
of vitamin K
• In past, a synthetic form of vitamin K was shown to
cause liver damage – this form is not available anymore
Vitamin A - vad är detta?
tamin A refers to any compound possessing the biological
activity of retinol. The term ‘retinoids’ includes both the
naturally occurring forms of vitamin A as well as the many
synthetic analogues of retinol
Intake of vitamin A in the Nordic
countries
• The mean intake of vitamin A in the Nordic countries
varies from 960 to 1,240 RE/10 MJ.
• The main sources of retinol are liver and liver products,
edible fat, milk, and dairy products including retinolfortified
margarine, spreads, and milk.
• The main sources of vitamin A-active carotenoids are
vegetables and some fruits
What happened if we don’t consume enough Vit A?
- Night blindness
- Irreversible blindness
- Weakened immunity
- Increased risk of illness and infections
- Reproductive system disorders
What happened if we consume too much Vit A?
• Highly toxic already at dose 3-4 times RDA
• During pregnancy – serious birth defects and
spontaneous abortions
• Lost of appetite, blurred vision
• Hair loss, Diarrhea
• Liver damage
Microbial impact on bone health
Production of short-chain
fatty acids in the lower gut
Modulation of the immune
system
Tea, coffee and bone health
Recent research has suggested that BMD is positively
associated with tea consumption, which may optimize bone
health by:
• maintaining higher BMD
• reducing the risk of fracture
