Study: Decreased bioavailability of vitamin D in obesity

Obese people need higher amounts of vitamin D, because much of the D consumed is deposited in fat tissue, where it can’t fight Covid. We need optimum vitamin D blood levels, which many now believe is 60-80ng/ml, much higher than what most people have.

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Decreased bioavailability of vitamin D in obesity


PMID: 10966885DOI: 10.1093/ajcn/72.3.690

Erratum in

Am J Clin Nutr. 2003 May;77(5):1342


Background: Obesity is associated with vitamin D insufficiency and secondary hyperparathyroidism.

Objective: This study assessed whether obesity alters the cutaneous production of vitamin D(3) (cholecalciferol) or the intestinal absorption of vitamin D(2) (ergocalciferol).

Design: Healthy, white, obese [body mass index (BMI; in kg/m(2)) > or = 30] and matched lean control subjects (BMI </= 25) received either whole-body ultraviolet radiation or a pharmacologic dose of vitamin D(2) orally.

Results: Obese subjects had significantly lower basal 25-hydroxyvitamin D concentrations [blood levels – ed.] and higher parathyroid hormone concentrations than did age-matched control subjects. Evaluation of blood vitamin D(3) concentrations 24 h after whole-body irradiation showed that the incremental increase in vitamin D(3) was 57% lower in obese than in nonobese subjects. The content of the vitamin D(3) precursor 7-dehydrocholesterol in the skin of obese and nonobese subjects did not differ significantly between groups nor did its conversion to previtamin D(3) after irradiation in vitro. The obese and nonobese subjects received an oral dose of 50000 IU (1.25 mg) vitamin D(2). BMI was inversely correlated with serum vitamin D(3) concentrations after irradiation (r = -0.55, P: = 0.003) and with peak serum vitamin D(2) concentrations after vitamin D(2) intake (r = -0.56, P: = 0.007).

Conclusions: Obesity-associated vitamin D insufficiency is likely due to the decreased bioavailability of vitamin D(3) from cutaneous and dietary sources because of its deposition in body fat compartments.


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