“Well there’s the rub, isn’t it? What is “sufficient””

I already asked that question:

“Apparently if dietary calcium is insufficient, homeostatic mechanisms keep the blood calcium level normal by removing calcium from bone. So how do you determine if someone is calcium deficent?”

I don’t think we are going to get an answer apart from some silent head scratching.

“I think it is important to view the results in absolute terms too.”

The authors seemed to have tried to. In the paper, it says:

“The number needed to treat (NNT) with calcium for five years to cause one incident event was 69 for myocardial infarction, 100 for stroke, 61 for any of myocardial infarction, stroke, or sudden death, and 77 for death.

And

“Incorporating the results from the current analysis of studies contributing patient-level data, treatment of 1,000 people with calcium for 5 years would cause an additional 14 MIs, 10 strokes, 13 deaths, and prevent 26 fractures.

“I would not conclude any effect on stroke with a p value of 0.11 in a study like this.”

So, if the hazard ratio remained 1.20 and P=0.04, what would you conclude?

In this study, is it that there is a real 20% increased risk of stroke and the study is not powered to detect a statistically signficant difference between groups, or, as you imply, there is no risk or one can’t draw conclusions (wasn’t sure which you favored).

If you are getting sufficient calcium and vitamin D from your diet, taking additional supplements is likely of no benefit.

Well there’s the rub, isn’t it? What is “sufficient”, and how do we know how much a person is actually consuming and successfully absorbing? How do the various nutrients interact with one another and other things in the food and what form of them is ideal (if indeed it’s only one that’s ideal)? I’m not asking this as a criticism, but more as a general observation. In most cases, we really don’t know the answers to these questions beyond the really obvious. Yet the whole philosophy behind supplementation (especially in the healthy) rests on an unreasonable expectation of precision on our answers to those questions.

I suspect a incorrect logical leap has been made which is common when basing clinical decision on epidemiological evidence alone – “low calcium levels = take more calcium” (similar to “high cholesterol = eat less cholesterol” or “fat person = low-fat diet”), but the body’s physiology often turns out to be more complicated than that.

Also, the results say little about calcium + vitamin D supplements (although Steve appears to be implying the opposite). In fact calcium + vitamin D trials because were excluded from the meta-analysis because”vitamin D deficiency has been associated with increased risk of cardiovascular disease and vitamin D supplementation with decreased mortality”.

High levels of parathyroid hormone (PTH) promotes osteoclasts which strip calcium from bones. Vitamin D increases calcium absorption in the gut and promotes osteoblasts which put calcium on bones. Vitamin D [25(OH)D] levels are inversely correlated to reduced PTH, i.e. vitamin D goes up and PTH goes down. PTH levels off when 25(OH)D levels reach 40ng/ml.

The International Osteoporosis Foundation recommends older adults need 800-2000 IU/day of vitamin D3 supplementation. They do not recommend calcium supplementation.

“Endocrinologist Peter Ebeling, who is medical director of Osteoporosis Australia, said the patients in the analysis had total calcium intakes of up to 2400 milligrams a day – far higher than the recommended intake of 1000 to 1300 milligrams.”

But here is the analysis from the actual study”

“When the cohort was divided by fifths of dietary calcium intake rounded to the nearest 100 mg/day, the respective hazard ratios (95% confidence intervals) for the effect of calcium treatment on myocardial infarction were 1.18 (0.70 to 2.00) for <500 mg/day, 0.68 (0.39 to 1.18) for 500-699 mg/day, 2.28 (1.26 to 4.15) for 700-899 mg/day, 1.81 (0.97 to 3.41) for 900-1099 mg/day, and 1.41 (0.81 to 2.48) for ≥1100 mg/day;”

Although the confidence intervals are fairly wide and extend into the insignificant range, the effect is greater at normal dose ranges.

Thoughts are usually implanted by something/someone else, so yes marketer’s are evil, in a sense, but they do no worse than any of us; when we give advice, counsel, or order.

If everyone had a proper diet for their circumstance (read size, locale, dietary restrictions), and had enough exercise, supplements would not be necessary. The issue is that most of us do not, and we know that innately. So we placate our shortcomings with things we think will help; whether that be “natural” supplements, illicit drugs, or anything else that gives us our edge.

Science has only come so far, and we certainly won’t be finding the fountain of youth any time soon. So we take the next best thing, which is what we perceive to be a step in reducing what ails us. Most of the time it is wasteful, as in we didn’t “need” it to begin with, but sometimes it is something beneficial. Such as the man who never goes outside taking a vitamin D supplement. Or the elderly lady with osteoporosis taking calcium. We don’t know exactly how it helps, but the idea that it is helping is often good enough. Long live the placebo, and also the real.

For night shifters, my understanding is that the cause of the increase in health problems is not clear. There are often references to disruptions in circadian rhythms, but night shifters may have other bad habits related to the shift… there are often sleep problems combined with an increased consumption of convenient junk foods. Fish oil supplements have demonstrated some benefits for secondary prevention of cardiovascular disease (or high triglycerides) , but I’m not sure that the evidence is there for primary prevention with shift work. If you like fish, eat it. I think if you have to work overnights, focusing on getting enough good sleep and trying to eat healthy overnight are probably the things to focus on.