Obezler takviye D vitamini alsalar bile bir faydası olmuyor.
A low vitamin D reading is usually treated as a minor lab finding. In people carrying abdominal fat, it marked the highest death rate in the study.
Researchers followed 5,520 adults aged 50 and over for six years and sorted them into six groups using two measurements that most people already have: a waist circumference and a blood vitamin D level. Vitamin D was split at the conventional thresholds, sufficient above 50 nmol/L, low between 30 and 50, and deficient below 30. The question was not whether either problem matters on its own, which has been asked many times. It was what happens when someone has both.
There are reasons to expect the two to interact. Vitamin D is fat-soluble, so a larger fat mass dilutes the same amount across a bigger volume and produces a lower reading. Genetic analysis in 42,024 adults shows the arrow runs that way and not the reverse: higher body mass lowers vitamin D, while vitamin D does not raise body mass. Abdominal fat is also the metabolically active kind, driving inflammation and insulin resistance, and vitamin D receptors sit on the immune cells involved in both. Two problems that plausibly compound each other rather than simply adding.
That is roughly what the numbers showed. Against people with a normal waist and normal vitamin D, those with abdominal obesity and normal vitamin D ran 1.47 times the risk of dying. Those with abdominal obesity and low vitamin D, 1.50. Those with abdominal obesity and deficient vitamin D, 2.23 times the risk, the highest of all six groups. Within that group, moving from a normal vitamin D level to deficiency took the risk from 1.47 to 2.23, while in lean people the equivalent step added nothing further.
This is observational, and nobody was assigned to anything. The pattern in the lean half of the study ran backwards, with merely low vitamin D looking slightly worse than outright deficiency, which is not how a cause behaves and is a reminder that some of this signal is noise. Low vitamin D also travels with being unwell, since people who are frail, housebound or inflamed have less sun exposure and lower readings, so part of what looks like risk from deficiency is illness that was already present. And because fat dilutes vitamin D, a low reading in a heavier person partly reflects body size rather than intake or sunlight, which means the same number does not mean the same thing in two different people.
The obvious next question has already been asked, and the answer is uncomfortable. Fifty-two randomised trials covering 75,454 people found vitamin D supplementation did not change deaths from any cause, and the trials agreed with each other almost perfectly. A trial giving 21,315 older adults high-dose vitamin D monthly for five years found the same. Death from cancer specifically did fall in the pooled trials, by about 16 percent, so the picture is not uniformly null. Against that, a genetic analysis of 307,601 people found risk of death climbing steeply as vitamin D fell below 50 nmol/L, with 25 percent higher odds at 25 nmol/L than at 50.
So the evidence points in two directions at once. Being genuinely deficient looks harmful. Handing supplements to populations that are mostly not deficient has not saved lives. Nobody has run the trial that this study argues for, which is supplementing people who have both abdominal obesity and true deficiency and seeing whether anything changes.
Until someone does, the practical value here is identification rather than treatment. If you carry weight around the middle and your vitamin D is below 30, you sit in the group this study flagged, and that is worth knowing and worth discussing with a doctor. What it does not tell you is that swallowing a capsule moves you out of it. The measurement is doing something useful. The pill has not yet been shown to.
da Silva Milliati et al., Diabetes Obes Metab 2026;28(8):6607-6617 · PMID 42092233
Zhang et al., BMJ 2019;366:l4673 · PMID 31405892
Neale et al., Lancet Diabetes Endocrinol 2022;10(2):120-128 · PMID 35026158
