Once foods in the United States were fortified with vitamin D, rickets appeared to have been conquered, and many considered major health problems from vitamin D deficiency resolved. But vitamin D deficiency is common. This review considers the role of vitamin D in skeletal and nonskeletal health and suggests strategies for the prevention and treatment of vitamin D deficiency.

Vitamin D Deficiency

admission. This proportion could already be greater in some parts of the country and may increase if referrals of cases of self-poisoning increase faster than the facilities for their assessment and management. The provision of social work and psychiatric expertise in casualty departments may be one means of preventing unnecessary medical admissions without risk to the patients. Dr Blake's and Dr Bramble's figures do not demonstrate, however, that any advantage would attach to medical teams taking over assessment from psychiatrists except that, by implication, assessments would be completed sooner by staff working on the ward full time. What the figures actually suggest is that if assessment of overdoses were left to house doctors there would be an increase in admissions to psychiatric units (by 19°U), outpatients (by 5O°'), and referrals to social services (by 140o). So for house doctors to assess overdoses would provide no economy for the psychiatric or social services. The study does not tell us what the consequences would have been for the six patients who the psychiatrists would have admitted but to whom the house doctors would have offered outpatient appointments. E J SALTER

Vitamin D deficiency.

In innate immune responses, activation of Toll-like receptors (TLRs) triggers direct antimicrobial activity against intracellular bacteria, which in murine, but not human, monocytes and macrophages is mediated principally by nitric oxide. We report here that TLR activation of human macrophages up-regulated expression of the vitamin D receptor and the vitamin D-1-hydroxylase genes, leading to induction of the antimicrobial peptide cathelicidin and killing of intracellular Mycobacterium tuberculosis. We also observed that sera from African-American individuals, known to have increased susceptibility to tuberculosis, had low 25-hydroxyvitamin D and were inefficient in supporting cathelicidin messenger RNA induction. These data support a link between TLRs and vitamin D-mediated innate immunity and suggest that differences in ability of human populations to produce vitamin D may contribute to susceptibility to microbial infection.

https://science.sciencemag.org/content/sci/311/5768/1770.full.pdf

Toll-Like Receptor Triggering of a Vitamin D-Mediated Human Antimicrobial Response

https://www.grc.com/health/pdf/Sunlight_and_Vitamin_D.pdf

Sunlight and vitamin D for bone health and prevention of autoimmune diseases, cancers, and cardiovascular disease

Vitamin D deficiency : a worldwide problem with health consequences

Objectives:The aim was to evaluate the association between serum vitamin D (25-hydroxyvitamin D) level and risk of prostate cancer. 
Methods:The nested case–control study was based on a 13-year follow-up of about 19,000 middle-aged men who attended the first screening visit within the Helsinki Heart Study and were free of clinically verified prostate cancer at baseline. Through record linkage with the files of the Finnish Cancer Registry, 149 prostate cancer cases were identified in the cohort. They were matched (1:4) to probability density sampled controls for age, time of sample retrieval, and residence. Serum levels of 25-hydroxyvitamin D (25-VD) at entry were measured for cases and controls. The relative risks of prostate cancer were derived using conditional logistic regression analysis. 
Results:Prostate cancer risk, analyzed by quartiles of the 25-VD levels, was inversely related to 25-VD. Men with 25-VD concentration below the median had an adjusted relative risk (OR) of 1.7 compared to men with 25-VD level above the median. The prostate cancer risk was highest among younger men (<52 years) at entry and low serum 25-VD (OR 3.1 nonadjusted and 3.5 adjusted). Among those younger men (<52 years), low 25-VD entailed a higher risk of non-localized cancers (OR 6.3). The mean age at diagnosis of the patients with 25-VD concentration above the median was 1.8 years higher than that of patients with vitamin D below the median (63.1 vs 61.3 years). 
Conclusions: We conclude that low levels of 25-VD associated with an increased risk for subsequent earlier exposure and more aggressive development of prostate cancer, especially before the andropause.

Prostate cancer risk and prediagnostic serum 25-hydroxyvitamin D levels (Finland).

Both high and low levels of blood vitamin D are associated with a higher prostate cancer risk : a longitudinal, nested case-control study in the Nordic countries.

https://onlinelibrary.wiley.com/doi/pdf/10.1002/ijc.11375

Both high and low levels of blood vitamin D are associated with a higher prostate cancer risk: a longitudinal, nested case-control study in the Nordic countries.

http://whale.to/v/Laaksi+07+Finland+vit+D+resp.pdf

An association of serum vitamin D concentrations < 40 nmol/L with acute respiratory tract infection in young Finnish men

Purpose of review Vitamin D is a seco-steroid hormone with multiple functions in the nervous system. We discuss clinical and experimental evidence of the role of vitamin D in normal and pathological brain functions, and analyze the relative importance of vitamin D-modulated brain mechanisms at different stages of life. We also outline perspectives for the use of vitamin D in clinical nutrition to prevent or treat various brain disorders. Recent findings Numerous brain dysfunctions are linked to vitamin D deficits and/or dysfunctions of its receptors. In both animals and humans, vitamin D serves as an important endogenous and/or exogenous regulator of neuroprotection, antiepileptic and anticalcification effects, neuro-immunomodulation, interplay with neurotransmitters and hormones, modulation of behaviors, brain ageing, and some other, less-explored, brain processes. Summary Vitamin D emerges as an important neurosteroid hormone in the brain, with a strong potential for age-specific applications in clinical nutrition.

Pentti Tuohimaa

Papers

Prostate cancer risk and prediagnostic serum 25-hydroxyvitamin D levels (Finland).

Both high and low levels of blood vitamin D are associated with a higher prostate cancer risk: a longitudinal, nested case-control study in the Nordic countries.

An association of serum vitamin D concentrations < 40 nmol/L with acute respiratory tract infection in young Finnish men

Neurosteroid hormone vitamin D and its utility in clinical nutrition.

The grooming analysis algorithm discriminates between different levels of anxiety in rats: potential utility for neurobehavioural stress research.