As many will know, radio-labeled glucose PET scans aren't very useful for PCa imaging, & there has been great interest in radio-labeled choline PET/CT. From a paper this month [1]:
"To date, several positron emission tomography/computed tomography (PET/CT) radiotracers including fluorine-18 fluorodeoxyglucose (18F-FDG), carbon-11 labeled choline (11C-choline), 18-F fluorocholine (18F-FCH) and carbon-11 acetate (11C-acetate) have already been assessed in the application of prostate cancer (PCa) diagnosis to some extent, the diagnostic efficiency of these radiotracers still remain controversial."
"A total of 56 studies containing 3,586 patients were included in this meta-analysis."
"When different radiotracers of PET/CT were compared, 18F-FCH-PET/CT was ranked as the most favorable ..."
Perhaps not perfect, but PCa cells do like to take up 18-F fluorocholine. Why do those cells want choline?
Choline is an honorary B vitamin. Thorne's "Basic B Complex" has 80 mg choline citrate. Other brands commonly use 25, 50 & 100 mg. A separate supplement might have 250 mg.
"The {adequate intake} for adult men is 550 mg/day." [2]
A large egg has 147 mg.
8 oz cod has 190 mg.
1 lb broccoli = 182 mg
8 oz chicken has 150 mg
(Eat any 3 of those 4 & you would still come up short.)
"Most common signs of choline deficiencies are fatty liver and hemorrhagic kidney necrosis."
"Mean choline intakes for older children, men, women, and pregnant women are far below the adequate intake level established by the {Institute of Medicine}." [3]
Men who consume a significant amount of alcohol daily are more likely to be deficient.
In other words, chances are that it is a struggle for many to attain the adequate intake in the absence of eggs. Eggs are singled out only because it's easier to squeeze in an extra egg than an extra 8 oz chicken, say.
[4] (2012 - U.S.) Health Professionals Follow-Up Study.
Erin Richman is probably responsible for many men with PCa giving up eggs.
"we observed 695 lethal prostate cancers"
"Men in the highest quintile of choline intake had a 70% increased risk of lethal prostate cancer"
Here is how the 695 deaths break down by choline quintile: 105, 123, 140, 155 & 172.
This doesn't look good. Inadequate intake is common, yet we have a linear mortality risk association. Looks like lower choline is always safer. LOL
Here are the median quintile choline intakes (mg/day): 305, 351, 385, 425 & 509.
These are all below the 550 mg adequacy level. To reduce choline intake in these circumstances is to risk fatty liver disease.
This is one of those situations where one needs to restate the findings. There is reduced PCa mortality risk as choline falls below optimal levels. Deficiency is protective. Under such circumstances one can hardly blame the humble egg.
"Biologic mechanisms linking higher choline intake to an increased risk of lethal prostate cancer are unknown."
...
One theory involves one-carbon metabolism. Choline is a methyl donor.
My own experience goes back 8? years, to when I injected B12 & saw significant PSA increases each month, for 4 months, after 6 straight months of no increase. Belatedly, I looked for studies & found that B12 deficiency might be protective.
At the center of one-carbon metabolism is the SAM (SAMe) cycle. SAM is the universal methyl donor in the body. PCa cells like to be hypermethylated. The DNA promoter regions for tumor suppressor genes are methylated (silenced) in PCa - never in normal cells.
Once SAM has dropped off its methyl to a cell, we are left with homocysteine. This can be recycled back through methionone to SAM if there is a dietary methyl donor. Typically, this would be folate (vitamin B9, from leafy greens). Other B vitamins are essential cofactors in homocysteine recycling - including vitamin B12. Many older men have impaired uptake of B12.
Choline is also a methyl donor.
Here's where it gets complicated. Folic acid fortification of grains became mandatory in 1996, & this was fully in place by 1998. Folic acid is a synthetic standin for folate.
"The U.S. program adds 140 µg of folic acid per 100 g of enriched cereal grain product and has been estimated to provide 100–200 µg of folic acid per day to women of childbearing age ..." Not to mention prepubescent girls, postmenopausal women - & males of all ages!
So, for U.S. men who eat bread or rice, methyl sufficiency has been the norm for 18 years.
"The Health Professionals Follow-Up Study is a prospective cohort study initiated in 1986" - twelve years before folic acid fortification.
Choline, as a methyl donor, would have become less significant after 1998.
Although choline can lower homocysteine, increase SAM levels, & add to PCa hypermethylation, PCa cells accumulate choline. If not for the methyl content, then what?
-Patrick
[1] ncbi.nlm.nih.gov/pubmed/273...
[2] en.wikipedia.org/wiki/Choline
[3] ncbi.nlm.nih.gov/pubmed/199...
Are eggs bad for PCa, round 2
