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"assuming that all heart disease is caused by vitamin D deficiency" - where is this assumption being made? I think the study is valuable in that it suggests bl

"assuming that all heart disease is caused by vitamin D deficiency" - where is this assumption being made? I think the study is valuable in that it suggests blindly giving everyone vitamin D is not strongly correlated with reduced cardiovascular events. I often see it stated that "nearly everyone" in developed countries is vitamin D deficient and so the majority of us should be supplementing. I think results like this make for a strong argument that it's more important to get your individual levels checked before you waste your money on supplements. One thing that's really important to note here is that the participants are all based in Australia. That's pretty significant considering the amount of sun Australians are exposed to. By some measures, Australia is the "sunniest" place in the world. And since exposure to sun causes your body to produce vitamin D, it's likely Australians have naturally higher levels than most other populations.

sgtnoodle 3y ago
There's at least two different lab tests for vitamin D, one that measures the level in its inactive form, and one that measures the level in its active form. The inactive level is what you'll get for a routine test. The other test takes a long time to process and is more expensive, and in my experience, health insurance really doesn't like having to pay for it. The active level is ultimately what's important because it's what's interacting with your bodily functions. The tricky bit is that the relationship between the two levels is fairly inconsistent from individual to individual, and variably determined by poorly understood mechanisms. A decent subset of the population has under-diagnosed inflammatory diseases, and for whatever reason inflammatory disease tends to increase the ratio of active to inactive vitamin D. Outside of rheumatology, this dynamic isn't really known about by most doctors. There's therefore a non-zero risk of vitamin D poisoning from supplementing based purely on low test results from a primary care provider. Regulating your inactive level to the "normal" range may unknowingly increase your active level to the point that it causes problems like hypercalcemia and eventual bone damage.

sgtnoodle 3y ago

There's at least two different lab tests for vitamin D, one that measures the level in its inactive form, and one that measures the level in its active form. The inactive level is what you'll get for a routine test. The other test takes a long time to process and is more expensive, and in my experience, health insurance really doesn't like having to pay for it. The active level is ultimately what's important because it's what's interacting with your bodily functions. The tricky bit is that the relationship between the two levels is fairly inconsistent from individual to individual, and variably determined by poorly understood mechanisms. A decent subset of the population has under-diagnosed inflammatory diseases, and for whatever reason inflammatory disease tends to increase the ratio of active to inactive vitamin D. Outside of rheumatology, this dynamic isn't really known about by most doctors. There's therefore a non-zero risk of vitamin D poisoning from supplementing based purely on low test results from a primary care provider. Regulating your inactive level to the "normal" range may unknowingly increase your active level to the point that it causes problems like hypercalcemia and eventual bone damage.