6. Vitamin D requirements of older adults

nmol/L for optimal bone mineral density

90-100

why is the endpoint of PTH not useful

massive range due to the massive factors affecting of PTH • diet: low protein and Ca intake will increase • exercise can reduced PTH • diurnal variations • insufficient intake can lead to insufficiency

are older adults at greater risk of vitamin D deficiency

- Common perception is that older adults are more at risk. - 80 is more optimal - Using 80 - most of the population is not having an adequate level - it's not just older people - Evidence in NZ does not support this is an older adult problem. It is across the board

are sitting rooms and sunblock helpful? WHat can we do instead

- If you can get people to adhere you will see reduction in falls and increase in status but it is challenging to get people to meet the recommendations. Age care facilities could change so there is more even pavement, have more attractive areas, - sitting in sunrooms is useless as UV rays that produce vitD don't pass through glass and the sunblock blocks the UV rays that prevent producing vitD in the skin

severe vitamin D deficiency

- Severe - < 12.5nmol/L o Results in osteomalacia, bone and muscle pains, weakness (rare in NZ/Aust)

Main predictors of vitamin D levels

- Sun exposure - Activity level

Response to simulated sunlight comparing ages

younger population big increase in serum vitD and less with older when exposed to sunlight

too much vit D?

links to increase in falls and increase in fractures by those taking supplements. contrary to what is hypothesised. however the study that found this had given a huge singluar dose of 500,000 which is huge. the only other study with these finding gave 300,000 annually. but ebenfits have been seen in the lower daily dose so it is likley that the adverse effects ar edose related. are high supplements safe to use?

supplement and sun exposure adherence

low adherence so can be difficult to determine the effects because of low adherence it was not an effective intervention. Reasons were not getting outside and getting sun exposure due to poor health, poor physical mobility preventing them from getting outside.

How to measure optimal serum 25(OH)D - the usual definition

optial for what> maximal suppression of PTH (leads to bone resorption and you lose Ca from bones - so people typically look at how much serum VitD will lead to max suppression of the hormone)

Factors potentially contirbuting to impaired vitamin D status in older age

Reduced sun exposure - less mobile, feel cold more, cover up, less physically able and therefore less likely to go out low intake (more important where sun exposure is low Impaired hydroxyation by kidney - 25(OH)D --> 1,25(OH)2D3 Reduced capacity of skin to synthesize pre-vitamin D3 - less 7-dehydrocholestrol in skin. this precursor leads to VitD. less of this in older adutls and a reduced capacity of older skin to produce pre-vitamin D3

vitamin D supplements and fracture risk

dose reponse relationship

risk of frailty in relationship to serum 25OH D levels

higher frailty at low and high serum levels - U shape curve

Alternative endpoints to find optimal serum vitD

o Bone mineral density o Lower extremity function o Falls o Dental health o Colorectal cancer prevention

optimal vitD for lower extremity function (leg)

90-100nmol/L

The ACC led programme

- ACC-led vitamin D supplementation (national falls prevention) programme - Initiated in 2007 o All new Zealand rest home residents eligible for prescribed vitamin D supplements: Loading dose: 2x 50,000 IU (1.25mg) cholecalciferol first month Maintenance dose: 50,000 IU per month for life No initial assessment of monitoring of vitamin D status o Monitoring of the effectiveness of the programme?

Vitamin D and muscle function

- Benefits for muscles (given sarcopenia is an issue and leads to frailty). - 1,25(OH)2D binds to a vit D specific nuclear receptor in muscle tissue - Leads to protein synthesis o Muscle cell growth and improved muscle strength o Direct benefit from vit D

barriers to greater sun exposure

- Fear of skin cancer o Many have already had experience with skin cancer. o High SPF will block out burns and also prevent vitamin production in the skin o Could take a supplement, just have shorter exposure and encourage them earlier in the day so they don't get burnt and then cover up. - Excursion mainly under cover - Fear of falling, colds - Lack of sheltered areas - Limited mobility

Frequency of outdoor activity and vitamin D

- Higher 25OHvitD in serum in those who are outdoors more frequently - Levels in over 60 in outdoors daily, no different from the lower levels who get - Less 7D, when older adults are outside daily they haven't he potential to end up with similar VitD levels as younger adults

T/F

- If you're older and get out every day you can have the same serum VitD levels as a younger person. Older people still have the capacity to benefit from sun exposure

should we use vitamin D supplments?

- Increase in falls and fractures (safety issues) where one large annual or monthly dosage is given. The best clinical benefits are seen around the daily RDI supplement use but will people adhere to taking a daily tablet? Most will not. - adherence low

Mild Vit D deficiency

- Mild - 25 to 50 nmol/L o Increases PTH (parathyroid hormone) secretion and bone turnover When PTH is elevated, promotes bone resorption so you lose Ca from the bone

Moderate vitD deficiency

- Moderate - 12.5 to 25 nmol/L o Associated with reduced bone density, high bone turnover, increased risk of hip fracture

Dietary recommendation for VitD in NZ and AUS 51-7-yr olds >70yr olds

51-7-yr olds - 400IU (10ug)/d >70yr olds - 600IU (15ug)/d

Vitamin D requirments based on the assumption of minimal exposure to maintain 25(OH)D in 97.5% sample: >25nmol/L --> >50nmol/L --> >80nmol/L -->

8.6ug/d 25ug/d 39ug/d

higher levels of serum vitD will lead to:

higher bone mineral density lower fracures lower colon cancer risk less timetaken to walk 8 feet (indicator of leg strength) - Attachment loss decreasing (periodontal health) - less vit D less attachment and tooth loss is more likely (attachment of the periodontal ligament to bone so people may be more likely to lose teeth) - Desirable level in this particular level is between 90 and 100nmol/L but beneifts seen at 70nmool/L - Conclusions of asssociationgs with 25(OH)D - Begins at 65nmol/l but best at 90-100nmol/L

Ireland study that looking at dietary intake - vitamin D status - how much vitD do they need to be consuming

increased with dietary intake but dpending on the amount of sun the summer beofre they needed to be consuming suggested that beween 8.6 an 11ug per day to avoid moderate deficiency. in nz from food we get about 2-3ug per day about 39 for optimal health which is way more than a typical diet so supplements are recommended

Institute of medicine vitD recommenedation To achieve serum 25(OH)D of 50 nmol/L <70 and >70

o <70 y = 600 IU (15ug) per day o > 70 y = 800 IU (20ug) per day

WHy si the serum level of vitD lower in the older adults compared to younger across different activity levels

o Might be because younger expose more skin, stay out longer when the go out or they might need more sun exposer to get the same vitamin D?

vitamin D deficiency can effect:

o Muscle weakness/atrophy o Poor physical performance o Postural sway o Impaired psychomotor function ^ falls, fractures, sarcopenia, frailty

what type of doses are/are not effective to vitamin D status (effect on strength and balance)

o Supplemental vitamin D with daily doses of 800-1000 IU (18-15mg per day) consistently demonstrated beneficial effects on strength and balance High single/weekly/monthly doses were not as consistent in demonstrating beneficial effects compared to the daily dose which is the most beneficial Keep at a consistently high level is important rather that large top ups

vitamin D and brain health

o Those with 25(OH)D <50nmol/l or 50-75nmol/L were more likely to have a decline in mini-mental state examination scores during 4.4 yr follow-up vs those > 75 nmol/L

possible mechanisms of vit D and brain helath

o Vitamin D = neuroprotective agent, potent antioxidant and has anti-inflammaotry activity (Alzheimer's disease is assoc with inflammatory processes including oxidative damage) o Vitamin D appears to play a role in vascular health in the rain (rats: increase stroke severity in vit D deficient group) o Vitamin D deficiency has been associated with increased risk of: autism, MS, Parkingsons's disease