New German study of British data below [1].
I was born on the SW coast of England at latitude 50 degrees. (Edinburgh, Scotland is at 56 degrees.) St. John's in Newfoundland, Canada, is at latitude 47.6 degrees, so one might expect the average Brit to have a much poorer vitamin D status than the average American, in the absence of supplementation.
"We {assessed} the associations of vitamin D deficiency, insufficiency, and vitamin D supplementation use with mortality from any cancer and 18 specific cancers in 411,436 United Kingdom Biobank participants, aged 40–69 years."
"The majority of the study population had either vitamin D deficiency (21.1%) or insufficiency (34.4%).
Too bad they don't give their definition of sufficiency. Did they use the British definition, which is quite low?
"The UK Scientific Advisory Committee for Nutrition has set the lowest level for defining sufficiency (10 ng/ml or 25 nmol/L) of any national advisory body or scientific society and consequently recommends supplementation with 10 micrograms (400 IU) per day." [2]
Back to the new paper:
"Furthermore, 4.1% and 20.3% of the participants regularly took vitamin D or multivitamin supplements, respectively."
Generally, the vitamin D amount in a multivitamin is low.
"During a median follow-up of 12.7 years, vitamin D deficiency was associated with significantly increased mortality from total cancer and four specific cancers: stomach (hazard ratio ... 1.42 ...), colorectal (1.27 ...), lung (1.24 ...), and prostate (1.36 ...)."
"Compared to non-users, vitamin D use was associated with lower lung cancer (0.75 ...) and total cancer mortality."
No mention of PCa, specifically, for the benefit of supplementation. And no mention of the typical supplement dose.
One problem with vitamin D supplementation for PCa, is that most men (imo) are unaware that PCa cells down-regulate the enzyme needed to convert inactive 25-D to the hormonal 1,25-D. {The 25-D 'reservoir' might be ample, but PCa cell resistance to 1,25-D is an early event and difficult to counter.} Further, I doubt that many are aware that PCa cells upregulate the enzyme that clears 1,25-D. If conversion does occur, the active form will be quickly metabolized.
The strategy for making circulating 1,25-D (from kidney production) more available to PCa cells is:
i) avoid excess calcium intake. The kidneys will not convert 25-D to 1,25-D if they are ditching calcium.
ii) fructose (I use it in coffee) will result in sustained levels of circulating 1,25-D. Be careful when using fruit for this purpose. Sugar profiles vary considerably. Note that table sugar (sucrose) will divide into fructose (good for PCa) & glucose (not good). (In spite of its name, fructose - i.e. fruit sugar - is not the sole sugar in fruit and amounts vary. Some fruits also contain free glucose & some contain sucrose. The USDA database is a useful guide. [3])
iii) Avoid excess phosphorus & phosphates. Some soft drinks & deli meats have phosphates. Also, large portions of fresh meat will provide a significant amount of phosphorus. Kidneys will be working on elimination & will not be converting 25-D to 1,25-D.
-Patrick
[1] sciencedirect.com/science/a...
Not quite full text.
[2] ncbi.nlm.nih.gov/pmc/articl....
[3] fdc.nal.usda.gov/fdc-app.ht...
Search on "fruit" to narrow the list. Click on a particular fruit to see the sugar breakdown.
Glutamine blockade to starve tumors, Using bacteria in the microbiome to attack cancer, 2 articles on finding dormant cancer cells in bone