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Vitamin D Reduced Dementia Risk by 40 Percent

re: correlation is not causation
re: Vitamin D and magnesium and Vitamin K2
re: dementia

I am a big fan of sunlight and the idea that Vitamin D has a major role to play. However, correlation is not causation.

Note the false and misleading title, which claims causality (“Reduced”). Which is not what has been shown. Virtually all news articles on any subject are dishonest in that claims of causality are made in the title, but are not substantiated in the actual article. Beware, no matter the source or subject! I would be OK with “Vitamin D Intake Associated with 40% Lower Risk of Dementia“—which is actually what has been shown.

Vitamin D Reduced Dementia Risk by 40 Percent


Vitamin D deficiency is associated with several health conditions and data show it can raise your risk of dementia, including Alzheimer’s disease.

  • A study in a cohort of 12,388 persons showed that vitamin D exposure over 10 years could lower the risk of dementia by 40 percent; women in the study experienced a greater benefit than men.
  • There are 50 million people worldwide with dementia and experts estimate that number will nearly triple by 2050; vitamin D deficiency is also a widespread problem with a worldwide prevalence of up to 1 billion people.
  • Vitamin D has a neuroprotective effect, can reduce the percentage of people who move from prediabetes to diabetes and can help prevent and/or treat certain cancers, gastrointestinal diseases, uterine fibroids, lupus, obesity, and neurodegenerative diseases such as multiple sclerosis.
  • There is a synergistic effect with magnesium, vitamin K2, and calcium and an imbalance may raise the risk of heart attack and stroke; the only way to determine how much sun exposure or supplementation you need is to test your vitamin D level.

Vitamin D is a fat-soluble vitamin, also referred to as calciferol. It can be found naturally in some foods and is produced endogenously when your skin is exposed to ultraviolet rays from the sun. Vitamin D supplementation in the United States is available as vitamin D2 (ergocalciferol) and vitamin D3 (cholecalciferol).[2]

The data demonstrating the efficacy of vitamin D in your health continue to mount and, as Campbell notes in his presentation, “This is cheap, it’s natural, it doesn’t cost anything and we’re not paying thousands of dollars per year to a pharmaceutical company.”[4]


WIND: causal or not, raising Vitamin D levels to be well in-range is surely a smart move, because we know how involved D is on numerous physiological processes.

Approaching 60, my body does not work like it did in my youth—I know from blood tests that even in summer sun my body does poorly at generating D from sunlight. What about you? Get a blood test and find out.

Always take magnesium and Vitamin K2 with Vitamin D to balance out the calcium in the D.

Controlling for what is easy to measure is weak-sauce science

...The researchers measured baseline exposure to vitamin D and compared dementia-free survival between the groups of individuals who were exposed to vitamin D and those who were not. Vitamin D exposure was measured as taking vitamin D3, vitamin D2, or vitamin D3 plus calcium. The results showed that across all these groups, exposure to vitamin D was associated with a significantly longer time period without dementia and a lower incidence rate overall.

The researchers controlled for other covariates such as gender, cognitive status, and apolipoprotein E (APOE) ε4. As Campbell explains,[6] the APOE gene is known to increase the risk of dementia in those who carry it. Approximately 25 percent of the population carries one APOE gene and 3 percent carries two. Individuals who have two genes will have a much higher risk than those who carry one.

...Campbell notes that this was a large effect and while it does not prove correlation or causation, it suggests the results are more likely to be causal. The researchers plotted out the data published in Figure A, which showed benefit to those exposed to vitamin D began roughly at the end of the first year and continued to confer greater benefit the longer the participants were followed.


I am inclined to believe that the Vitamin D supplementation is causal.

However, this is very weak “science”: the researchers controlled for what they could easily measure, which is a pathetic standard. But it’s the norm, which is why most science today is total garbage. Which is not saying the finding are incorrect, only that the “results” stray quite from scientific credibility.

“vitamin D exposure over 10 years” is an incredibly vague standard. What in heck does it even mean and how did they verify it?

The researchers did not study Vitamin D blood levels (no data!), did not study why their subjects took Vitamin D. Those with dementia seem a lot less likely to be motivated to think of supplementation (let alone do so), to exercise, to take an outdoor walk everyday, etc. And what about income levels and overall nutrition? Controlling for “cognitive status” might address some of that a little, but it is far from persuasive. A huge range of factors are involved, none of which were studied.

In other words, the researchers failed to control for major factors eg the actual lifestyle behaviors of the subjects, their income, nutrition, living conditions, etc.

As much as I am a fan of the idea of Vitamin D being a good idea, this looks like a horse-shit study swiss-cheesed with methodological holes and huge gaps of insight by missing data. I see no basis for asserting causality here.

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