Objective: The objective of the present study was to examine knowledge on vitamin D and calcium in a cohort of older adults and to test the association between health knowledge, vitamin D status and dietary calcium intake.
Methods: The participants of this cross-sectional survey consisted of 426 individuals (≥65 years), living in residential homes. Participants were tested for their knowledge on vitamin D and calcium using a standardized questionnaire. Serum 25-hydroxyvitamin D3 (25(OH)D3) levels and dietary calcium intake were measured.
Results: The mean serum 25(OH)D3 level was 39.1 (±21.4) nmol/l and the mean daily dietary calcium intake was 826 (±242) mg/day. Of the participants, only 38 per cent indicated that they knew or had heard of vitamin D. Participants overestimated their daily calcium intake. Better knowledge on vitamin D and calcium was associated with both higher vitamin D levels (P < 0.0001) and a higher daily dietary calcium intake (P < 0.0001).
Conclusion: Given the poor knowledge on vitamin D and calcium and the observed associations, improving health knowledge could be a possible intervention to improve vitamin D status and calcium intake in older people. Further studies are needed to assess whether education will indeed lead to improvement of vitamin D levels and calcium intake in this age group.
Consensus development conference: diagnosis, prophylaxis, and treatment of osteoporosis. Am J Med1993; 94: 646–650.
2.
LookerACJohnstonCCWahnerHW. Prevalence of low femoral bone density in older U.S. women from NHANES III. J Bone Miner Res1995; 10: 796–802.
3.
HolickMF. Vitamin D deficiency. N Engl J Med2007; 357: 266–281.
4.
OudshoornCvan der CammenTJMcMurdoMEvan LeeuwenJPColinEM. Ageing and vitamin D deficiency: effects on calcium homeostasis and considerations for vitamin D supplementation. Br J Nutr2009; 101: 1597–1606.
5.
ScottTLGazmararianJAWilliamsMVBakerDW. Health literacy and preventive health care use among Medicare enrollees in a managed care organization. Med Care2002; 40: 395–404.
6.
VuLHvan der PolsJCWhitemanDCKimlinMGNealeRE. Knowledge and attitudes about Vitamin D and impact on sun protection practices among urban office workers in Brisbane, Australia. Cancer Epidemiol Biomarkers Prev2010; 19: 1784–1789.
7.
National Osteoporosis Society. Your bones and osteoporosis: what every man, woman and child should know. National Osteoporosis Society, 2009.
8.
JandaMYoulPBolzKNilandCKimlinM. Knowledge about health benefits of vitamin D in Queensland Australia. Prev Med2010; 50: 215–216.
9.
FolsteinMFFolsteinSEMcHughPR. “Mini-mental state”. A practical method for grading the cognitive state of patients for the clinician. J Psychiatr Res1975; 12: 189–198.
Bischoff-FerrariHAKielDPDawson-HughesB. Dietary calcium and serum 25-hydroxyvitamin D status in relation to BMD among U.S. adults. J Bone Miner Res2009; 24: 935–942.
12.
LipsP. Vitamin D deficiency and secondary hyperparathyroidism in the elderly: consequences for bone loss and fractures and therapeutic implications. Endocr Rev2001; 22, 477–501
13.
LipsP. Worldwide status of vitamin D nutrition. J Steroid Biochem Mol Biol2010; 121, 297–300.
14.
Bischoff-FerrariH. Vitamin D: what is an adequate vitamin D level and how much supplementation is necessary?Best Pract Res Clin Rheumatol2009; 23: 789–795.
15.
Health Council of the Netherlands. Towards an adequate intake of vitamin D. Publication no. 2008/15. The Hague: Health Council of the Netherlands, 2008.
16.
Insitute of Medicine. Dietary reference intakes for calcium and vitamin D. IOM Consens Statement. November2010.
17.
FrancisRMAndersonFHPatelSSahotaOvan StaaTP. Calcium and vitamin D in the prevention of osteoporotic fractures. QJM2006; 99: 355–363.
18.
FardellonePCotteFERouxCLespessaillesEMercierFGaudinAF. Calcium intake and the risk of osteoporosis and fractures in French women. Joint Bone Spine2010; 77: 154–158.
19.
KudlacekSSchneiderBPeterlikM. Assessment of vitamin D and calcium status in healthy adult Austrians. Eur J Clin Invest2003; 33: 323–331.
20.
KoekWNvan MeursJBvan der EerdenBC. The T-13910C polymorphism in the lactase phlorizin hydrolase gene is associated with differences in serum calcium levels and calcium intake. J Bone Miner Res2010; 25: 1980–1987.
21.
EatonL. A theme issue for medics and an increasingly health informed public. Br Med J2002; 325: 984.
22.
EngelsYvan AssemaPDorantELechnerL. Factors associated with the intention to use vitamin D supplements: quantitative study among a sample of elderly people in a medium-sized town in the Netherlands. J Nutr Educ2001; 33: 134–142.
23.
BohatyKRocoleHWehlingKWaltmanN. Testing the effectiveness of an educational intervention to increase dietary intake of calcium and vitamin D in young adult women. J Am Acad Nurse Pract2008; 20: 93–99.
24.
KungAWLeeKK. Knowledge of vitamin D and perceptions and attitudes toward sunlight among Chinese middle-aged and elderly women: a population survey in Hong Kong. BMC Publ Health2006; 6: 226.
25.
NielsenDRygJNielsenWKnoldBNissenNBrixenK. Patient education in groups increases knowledge of osteoporosis and adherence to treatment: a two-year randomized controlled trial. Patient Educ Couns2010; 81: 155–160.
