Another in my alphabetic tour.
I get the sense that the risk of dairy/calcium in PCa is fairly well-known among men with PCa. In essence, that translates to avoidance of dairy & high-dose calcium supplements.
First, I should state my belief that treating a loss of bone density by simply topping up with high-dose calcium makes no sense, since it doesn't address the problem.
In 2013, the U.S. Preventive Services Task Force came out against calcium as being effective against avoiding fractures in men & women.
Also in 2013, the large NIH / AARP Diet and Health Study reported that [1]:
"... high intake of supplemental calcium is associated with an excess risk of CVD death in men ..."
(Men with PCa are noted for already having increased CVD risk.)
There are many factors involved in bone health, & calcium is not a quick fix - but that's a separate topic.
Many older men have probably used a multimineral containing calcium - even men without osteopenia or osteoporosis.
As I mentioned elsewhere - before dairy farms & calcium pills, men had sufficient bone health to go out hunting & gathering. The diet somehow provided enough. Note that small levels of calcium do get used-up in the body. However, under normal circumstances, bone remodeling associated with maintaining circulating calcium homeostasis does not result in significant loss of calcium. The healthy body conserves calcium. It's not natural for significant amounts of calcium to leach from bones into the urine.
Humans are the only mammals where milk (from a different species) is considered essential to the bone health of infants weaned from human milk. In some parts of the world, there is no dairy tradition, & the children do just fine. But U.S. children enter adulthood with the idea that it is difficult to obtain adequate calcium. "Got milk?" (Blame the advertising agency Goodby Silverstein & Partners for that one.)
Meanwhile, the dairy industry finds more outlets for its products. In 1970, a person in America ate, on average, eight pounds of cheese in a year. Now it’s 23. Twenty-three pounds of cheese a year! [2] That was in 2010 & the trend is upward. When you add in ice cream & yogurt, that's a lot of calcium, even without factoring in milk.
There is only so much salt, sugar & fat one can add to a restaurant meal, but one can never add too much cheese. LOL
[End of rant.]
In 2001, Giovannucci [3] reported that:
"Dairy product intake increased risk of metastatic prostate cancer {by 40%} for top vs. bottom quintile comparison, but no association remained after controlling for calcium ..."
Again with Giovannucci [4], 2001:
"At baseline, men who consumed >600 mg Ca/d from skim milk had lower plasma 1,25(OH)(2)D(3) concentrations than did those consuming < or =150 mg Ca/d"
Interest in vitamin D was just warming up 15 years ago, but Edward G. had made the connection: calcium lowered hormonal vitamin D. From this point on, researchers included calcium in PCa-dairy studies.
In 2002, Giovannucci sat in on another study [5]:
"Our results support the hypothesis that very high calcium intake, above the recommended intake for men, may modestly increase risk of prostate cancer."
In a 2005 U,S, study [6]:
" Low-fat milk was associated with increased risk (RR = 1.5 ... third compared with first tertile ...)"
"Dairy consumption may increase prostate cancer risk through a calcium-related pathway."
Interestingly, whole fat milk was not associate with PCa.
In 2007, we get the scary Giovannucci study [7]:
"Higher calcium intake was not appreciably associated with total or nonadvanced prostate cancer but was associated with a higher risk of advanced and fatal prostate cancer [for fatal prostate cancer, compared with men whose long-term calcium intake was 500-749 mg/d (excluding supplement use of <5 years); those with intakes of 1,500-1,999 mg/d had a RR, 1.87 ..; and those with > or = 2,000 mg/d had a RR, 2.43 ...]. "
"Dietary calcium and supplementary calcium were independently associated with an increased risk. For high-grade prostate cancer (Gleason > or = 7), an association was observed for high versus low calcium intake (RR, 1.89 ...), but a nonsignificant, inverse association was observed for organ-confined, low-grade prostate cancer (RR, 0.79 ...)."
"In a sample of this cohort, higher calcium intake was associated with lower circulating 1,25(OH)2 vitamin D levels. Our findings suggest that calcium intakes exceeding 1,500 mg/d may be associated with a decrease in differentiation in prostate cancer and ultimately with a higher risk of advanced and fatal prostate cancer but not with well-differentiated, organ-confined cancers."
A 2007 U.S. study [8] differed from the above:
"In this large prospective study in a prostate cancer screening trial, greater dietary intake of calcium and dairy products, particularly low-fat types, may be modestly associated with increased risks for nonaggressive prostate cancer, but was unrelated to aggressive disease. Furthermore, we found no relationship between calcium intake and circulating vitamin D."
In 2009, in another U.S. study [9], Giovannucci was forced to state that:
"Our findings, in a sample including a large proportion of black participants, do not confirm previous findings showing an inverse association between calcium intake and 1,25(OH)2D levels. As such, they suggest that future work should explore other mechanisms by which dairy foods and calcium might increase prostate cancer risk."
Giovannucci in 2012 [10]: "Men with the highest versus lowest intake of whole milk were at an increased risk of progression (HR = 2.15 ...)" whereas: "Men in the highest versus lowest quintile of low-fat dairy intake were at a decreased risk of progression (HR = 0.62 ...)"
In 2015, Giovannucci introduces a confounding factor: phosphorus [11]. Dairy products contain phosphorus, although it is found in meat & fish in significant amounts too. Phosphorus/phosphates have been associated with PCa progression risk. One should avoid deli meats & soft drinks with phosphates. As with excess calcium, excess phosphorus will inhibit the conversion of vitamin D to its hormonal form. (Excess phosphorus causes the hormone FGF-23 to be secreted. Not only does it inhibit the production of 1,25(OH)2D, but it accelerates its degradation. None of this is mentioned in the paper, though.)
"Calcium intakes >2000 mg/d were associated with greater risk of total prostate cancer and lethal and high-grade cancers. These associations were attenuated ... when phosphorus intake was adjusted for."
"Phosphorus intake was associated with greater risk of total, lethal, and high-grade cancers, independent of calcium and intakes of red meat, white meat, dairy, and fish."
"Calcium intake was associated with an increased risk of advanced-stage and high-grade disease 12–16 y after exposure, whereas high phosphorus was associated with increased risk of advanced-stage and high-grade disease 0–8 y after exposure."
"Given the high correlation between calcium and phosphorus intake, because dairy is the major contributor of both minerals in this population, it is difficult to truly separate their effects."
After 15 years I would have expected more clarity. Anyway, dairy has other issues (that I will get to), & the NIH/AARP study is a strong warning against supplemental calcium.
-Patrick
[1] archinte.jamanetwork.com/ar...
[2] theatlantic.com/health/arch...
[3] ncbi.nlm.nih.gov/pubmed/115...
[4] ajcn.nutrition.org/content/...
[5] cebp.aacrjournals.org/conte...
[6] ajcn.nutrition.org/content/...
[7] cebp.aacrjournals.org/conte...
[8] cebp.aacrjournals.org/conte...
[9] ncbi.nlm.nih.gov/pmc/articl...
[10] cebp.aacrjournals.org/conte...
[11] ajcn.nutrition.org/content/...
