The challenge of achieving vitamin D adequacy for residents living in long-term care

In this issue, Robbins and co-workers report a study of vitamin D supplement use in long-term care (LTC) homes in the USA(1) that is an important reminder of the need to consider how those living in sun-deprived situations can meet their need for vitamin D, especially those with higher dietary recommendations than the rest of the population due to their age and/or medical conditions. These investigators used a natural experiment to determine the type and content of supplements that successfully met the vitamin D needs of LTC residents. However, as will be described, allowing residents in LTC to choose the type of vitamin D supplements can have a hit-or-miss outcome. Robbins et al. show the evidence for this with only 43 % of residents consuming 20 μg/d which was calculated as necessary to maintain adequacy, while 9% of residents risked consuming greater than the Upper Level of 100 μg/d which is more than the intake needed to maintain adequacy. LTC facilities are essential components of elder care in Western countries. LTC homes (also called nursing homes, skilled nursing facilities and care homes) are residential care facilities for those who can no longer independently manage activities of daily living and include health and social care provision. A spectrum of LTC homes exists, including private and public funded as well as for-profit and not-for-profit status(2). Care is predominantly supported by care aides (also called continuing care assistants, nursing assistants and personal support workers) who are ‘unregulated’, i.e. do not have professional status or certified credentials. Residents have access to medical care via physician, nurse and allied provider services (e.g. dietitian, physical and occupational therapist and speechlanguage pathologist) who are regulated or trained certified providers. A standard of care is typically legislated federally or by state/province, for example, in the USA by the Centers for Medicare & Medicaid Services(3). Assessment of nutritional status and needs as well as provision of an appropriate and acceptable diet that satisfies dietary requirements is often required, inclusive of those residents requiring a therapeutic diet or texture modification. Nevertheless, the LTC facilities’ financial status can lead to limitations that reduce or prevent residents from achieving optimal dietary intake and nutrition care. Combined with the increased level of acuity of resident healthcare needs and comorbid conditions, malnutrition is a common issue among elderly residents in LTC homes(4). Widespread public health awareness of vitamin D deficiency in the USA was not recognised as a particularly serious problem for older adults until the 1997 Dietary Reference Intake report from the Institute of Medicine(5). The 1997 recommendations for adults 50 to 70 years of age were doubled from a previous 1985 Recommended Dietary Allowance (RDA) of only 5 μg/d(6) to 10 μg/d and tripled to 15 μg/d for adults over 70 years. The reason for the change in 1997 was due to compelling evidence that the vitamin D status of older adults was much lower than expected. Researchers found very low circulating levels of 25-hydroxyvitamin D (25(OH)D), the main indicator of vitamin D status(5), in homebound and institutionalised older adults even when they consumed vitamin D at levels of 10 μg/d, a level which was twice the 1985 RDA(7). In 2011, the National Academy of Sciences Engineering and Medicine (NAM, formerly, IOM) set RDAs at an even higher levels, with all ages between 1 and 70 years having an RDA of 15 μg/d and those over 70 years having an RDA of 20 μg/d(8). It has been recognised that older adults have increased needs due to metabolic inefficiencies in vitamin D metabolism and skin synthetic capacity(8). In agreement with this notion, many other government bodies around the world have also made recommendations for vitamin D since 2011, and most range between 15 and 20 μg/d for adults> 75 years of age(9). The target 25(OH)D level for the recommendations also vary, most following what the NAM 2011 report determined to represent sufficiency which is 25(OH)D concentrations of 50 nmol/l(8). However, a higher 25(OH)D level set at 75 nmol/l is used by the Endocrine Society(10) based on evidence of greater need in older adults who are at greater risk for chronic diseases; other organisations havemade similar recommendations(11) and put forth the argument that in situations where the person is not healthy (usingmedications compromising vitamin Dmetabolism or suppressing immune response, or having serious comorbidities), a higher intake is justified. Table 1 shows the recommended levels of vitamin D intake for older men and women in various countries and those recommended by different professional societies impacting the health of the older adults. Public Health Nutrition: 25(1), 90–93 doi:10.1017/S136898002100238X