Major Minerals & Bone Health Flashcards
What are minerals?
- inorganic elements needed for structure and regulation of body processes
- in periodic table
- Na, Mg, K, Ca, P, S, Cl
- not sensitive to light, heat, oxygen, or acid
- most often are cofactors for reactions
What does organic usually mean?
Carbon based
How are minerals classified?
- major minerals: amount needed >100 mg/day (make up >0.01% body weight) - trace elements required in amounts <100 mg/day (exist as <0.01% of body weight)
Where are minerals found in the diet?
- grain products and meat and alternatives have a wide range of minerals
- dairy good source of calcium, zinc, potassium
- fruits and veg also good source of iron, calcium, potassium, magnesium
What factors affect the bioavailability of minerals?
- life stage may affect absorption (eg. calcium)
- absorption of minerals of the same charge depends on the amount of each in a meal – eg. high Ca2+ meal may inhibit absorption of Fe2+
- too many of one may inhibit another
- dietary components enhance or inhibit absorption (eg. phytates, tannins and oxalates bind minerals preventing absorption)
What chemicals inhibit absorption of minerals?
- phytates (bind minerals in grains)
- tannins (in tea and wine)
- oxalates
Why do pregnant women not need to intake more calcium?
- they absorb more from diet
How do minerals act as cofactors?
- complete the enzyme and make it active and able to bind to its substrate
What minerals provide structural support?
Calcium, phosphorus, magnesium
What minerals have a high prevalence of inadequate intake?
Calcium, magnesium, potassium
What food is calcium found in?
- canned fish w bones
- dairy products
- leafy greens
- nuts
The most abundant mineral in our body is…
Calcium
Calcium can be absorbed both…
Passively and actively; passive more so w high intakes, otherwise need transport protein
As the percent of calcium ingested increased…
Absorption decreases
How is calcium important for bone health?
- more calcium favours bone formation, prevents resorption
- very important in youth
What cells enact bone remodelling?
- osteoblasts cause bone formation
- osteoclasts cause bone degradation
Bone is constantly…
Remodelling, favouring formation early in life, degradation later in lafe
What recent dietary shift has contribute to inadequate calcium intake in youth?
- replacement of milk with soda
- more sugar, less nutrients
- greater dairy intake in adolescence linked with lower incidence of T2DM in middle-aged women
What nutrient is shown to increase calcium absorption and thus improve bone health?
- Inulin
- prebiotic carb that organisms feed on
- soluble fiber derived from chicory root
- increases bone density
- found in fruits and vegetables
What are the types of bone?
- trabecular (spongy) bone is found in the pelvis, wrists, vertebrae, and knobby ends of long bones
- cortical (compact) bone is sturdy, and makes up the dense outer layers of bone; about 80% of the skeleton consists of cortical bone
Which type of bone is more susceptible to osteoporosis and why?
- trabecular bone
- has a greater surface area and experiences greater turnover
- therefore there is a greater risk of loss in areas such as hips
What factors affect osteoporosis risk?
- advanced age
- genetics (light skin, smaller frame)
- gender (women)
- hormone levels
- lifestyle
Leading cause of fractures in those over 60?
Osteoporosis
What trends are seen in bone mass throughout the lifespan?
- increases through childhood, peaking at age 35
- start losing bone mass steadily after age 35
- in women, bone loss accelerated for about 5 years after menopause
What is the function of phosphorus?
- about 85% in bones and teeth
- also involved in regulatory processes
- needed for phospholipids in cell membrane
- RNA and DNA synthesis
- part of phosphate buffer system that maintains intracellular pH
- forms ATP and creatine phosphate for energy
- signal transduction; added or removed from enzymes to activate/deactivate them
Phosphorus is most often found as part of…
A phosphate group
Which is available in more foods, phosphorus or calcium?
Phosphorus
How is vitamin D involved in phosphorus utilization?
- vitamin D involved in active transport
- however, can be absorbed without the aid of vitamin D
What foods is phosphorus found in?
- most foods
- higher levels in meat, nuts, seeds, dairy, grain products
What is the function of magnesium?
- provides structure, important in maintenance of bones - about half of body Mg is in bones, remainder is inside cells
- cofactor for > 300 enzymes; it is involved in energy metabolism and the Na+:K+ pump
- vital for dividing cells, DNA and RNA synthesis require it, as do all stages of protein translation
- stabilizes the high energy compounds
- helps to synthesize proteins, nucleic acids, and fats
What foods is magnesium found in?
- spinach, sunflower sees, almonds, beans
- other non-processed foods
What is the function of sulphur?
- obtained in dietary protein and in food preservatives (antioxidants)
- part of methionine and cysteine; cysteine is also a component of glutathione (which is an endogenous antioxidant)
- with adequate protein intake, no deficiency of sulphur occurs
- no recommended intake (thiamin & biotin contain S too)
With the known role of calcium in kidney stones, should it be limited?
- no; reduced calcium intake is not recommended based on research that shows this encourages greater oxalate absorption
- would actually worsen kidney stones to limit it
What other dietary changes reduce kidney stone incidences?
- increased fruit and veg intake
- increased water intake (easy to do)
- DASH diet
- plant proteins
What may aggravate kidney stones?
- grapefruit and apple juices, cola, and tea (other than beneficial green tea) because of the oxalate content
