Vitamin D supplementation in African Americans: dose-response

Abstract

Nut consumption decreases risk of some diseasesDear Sir:We read with interest the recent meta-analysis of nut consumption and risk of cardiovascular disease and type 2 diabetes (1). The authors reported that high consumption of nuts decreased the risk of coronary artery disease and hypertension but not stroke or type 2 diabetes. A meta-analysis in this field is very important because the results have been inconsistent, and the authors clarified this association. However, 2 of the studies (2, 3) might not be suitable to be included in their meta-analysis because both reported the association between intake of nuts plus fruit and risk of coronary artery disease. However, after exclusion of those 2 studies, the pooled RR and 95% CI of a 1-serving/d increase did not substantially change the findings (RR: 0.76; 95% CI: 0.66, 0.88).Neither of the authors declared a conflict of interest. Min Zhao Department of Nutrition and Food Reply to M Zhao and W LiuDear Sir:We thank Zhao and Liu for their comments. We agree that our published meta-analysis (1) included 2 potentially ineligible studies that used nuts and fruit in combination as the exposure variable. However, as stated by Zhao and Liu, the inclusion of both studies did not affect our results and the association was even stronger after exclusion of those 2 studies.Neither of the authors declared a conflict of interest. Donghao Zhou

Fortification of yogurts with vitamin D and calcium enhances the inhibition of serum parathyroid hormone and bone resorption markers: A double blind randomized controlled trial in women over 60 living in a community dwelling home

“…Controversy on the outcome of vitamin D on bone health, fragility fractures and falls can be explained, at least in part, by differences between: supplemental doses; duration of supplementation; ethnic/racial target populations; baseline vitamin D status ( 21 – 30 ). Furthermore, interpretation in terms of inadequacy/adequacy of serum 25OHD baseline levels and-or intervention-induced changes in response to supplemental vitamin D can differ when related to the concept of the “Estimated Average Requirement (EAR) or to the “Recommended Dietary Allowance (RDA)”, as well as to the method of assessment ( 31 , 32 ). The notion of inadequacy/ adequacy of the vitamin D status is still much more difficult to delineate when putative extraskeletal effects are considered.…”

Vitamin D Requirements for the Future—Lessons Learned and Charting a Path Forward

“…For example, at a median intake equal to the AR, 50% of a population group will have intakes that may be inadequate for the chosen criterion of nutritional status [ 5 ]. Some of the panellists in the IOM DRI committee have suggested that given the inherent variability, the appropriate approach to achieve a low prevalence of vitamin D inadequacy within a population group—as verified by statistical modelling—is to shift the intake distribution so that most of the population (97.5%) have vitamin D intakes above the EAR of 10 μg/day (not above the RDA) [ 21 ].…”

Ethnic disparities in the dietary requirement for vitamin D during pregnancy: considerations for nutrition policy and research

“…Moving beyond the comparative studies, results from a large, four-arm (placebo and 25, 50 and 100 µg/d) randomised trial in African American adults reported a vitamin D intake of 41 µg/d was needed to reach the RDA-associated 25(OH)D threshold of 50 nmol/l (74) , but this study has been criticised in terms of its design and interpretation. Firstly, Brannon et al (2) have disputed the need for such high doses of vitamin D, stating the aim should not be to achieve a population intake equivalent to the RDA, as to do so would result in a shift in the population distribution of 25(OH)D to values that exceed the upper limit where the risk of hypercalcaemia increases sharply. Brannon et al claim that dose-response trials should focus on the estimations of the EAR, for which dietary requirements refer to the needs of the population rather than the individual (2) .…”

“…Firstly, Brannon et al (2) have disputed the need for such high doses of vitamin D, stating the aim should not be to achieve a population intake equivalent to the RDA, as to do so would result in a shift in the population distribution of 25(OH)D to values that exceed the upper limit where the risk of hypercalcaemia increases sharply. Brannon et al claim that dose-response trials should focus on the estimations of the EAR, for which dietary requirements refer to the needs of the population rather than the individual (2) . However, unlike many nutrients, estimation of both an EAR and RDA is possible through dose-response trials with vitamin D, as 25(OH)D is a valid biomarker of exposure and conditions of minimal UVB availability are achieved at high latitude in winter.…”

“…In response to the comments provided by Brannon et al (2) , the authors published supplementary data corresponding to an intake level of 30 µg/d to reach the EAR-associated threshold of 40 nmol/l in 97•5 % of the study population (75) . The major drawback of this study (2) is that the dose-response modelling used in the DRV estimation does not consider background dietary vitamin D intakes as the authors felt this was negligible at <5 µg/d. Hence, the intake values reported in this study (75) can only be interpreted as the supplementation dose needed to achieve specific 25(OH)D thresholds, in addition to that obtained from diet.…”