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Previous Mendelian randomization (MR) studies on 25-hydroxyvitamin D (25(OH)D) and cancer have typically adopted a handful of variants and found no relationship between 25(OH)D and cancer; however, issues of horizontal pleiotropy cannot be reliably addressed. Using a larger set of variants associated with 25(OH)D (74 SNPs, up from 6 previously), we perform a unified MR analysis to re-evaluate the relationship between 25(OH)D and ten cancers. Our findings are broadly consistent with previous MR studies indicating no relationship, apart from ovarian cancers (OR 0.89; 95% C.I: 0.82 to 0.96 per 1 SD change in 25(OH)D concentration) and basal cell carcinoma (OR 1.16; 95% C.I.: 1.04 to 1.28). However, after adjustment for pigmentation related variables in a multivariable MR framework, the BCC findings were attenuated. Here we report that lower 25(OH)D is unlikely to be a causal risk factor for most cancers, with our study providing more precise confidence intervals than previously possible., Studies of the genetic association between vitamin D and cancer risk have typically been underpowered. Here the authors analyse this using Mendelian Randomisation with more than 70 vitamin D variants obtained from the UK Biobank and large-scale data from various consortia, confirming null associations between vitamin D and most cancers.

The rate of incorporation of organic carbon by Daphnia p&x from various concentrations of ‘“C-labeled phytoplankton and artificial detritus was measured both in situ in West Blue Lake, Manitoba, and in the laboratory. Incorporation of artificial detritus was independent of dissolved oxygen concentration, down to a level of 2,.8 mg OS/liter, during a 4-hr experiment. Food concentration and tcmpcraturc were related, for each food type, to incorporation in multiple regression equations. Three estimates, ranging from 2.37 to 5.35 ,ug C individual-’ day”, were made of daily incorporation, assuming it was similar in natural and artificial detritus. Of these amounts, from 12 to 17% was estimated to be incorporated by Daphnia below 12 m, in the zone where particulate organic matter was predominantly detritus or moribund organisms. Variations in incorporation rate were caused primarily by temperature differences encountered during vertical migration rather than by food concentration. &cause vertical migration patterns varied, temperature regimes also varied, and so, conscqucntly, did incorporation rates. The estimated contribution of detrital carbon to total daily incorporation was much less than the phytoplankton contribution but was significant