Hi Gabes,
My take on this is that yes, if you take vitamin D, then you should also take magnesium (for the reasons cited in the quote). But arguably the largest consumption (by far) of magnesium goes to the task of getting calcium out of the blood and into the cells (in the bones and other tissues), or disposing of excess amounts. This is true because the more vitamin D we take, the more calcium we will absorb (whether we need the additional amount of calcium or not). And because it's magnesium's job to get the calcium out of the blood (including the excess amounts that are unneeded at the moment), this is a critical process, so it will be given priority which means that the magnesium will be used without regard to holding back reserves. It's critical because if the level of calcium in the blood is allowed to stray too far above (or below) the so-called "normal" range, the risk of an adverse cardiovascular event (such as heart attack or stroke) can increase dramatically.
So the more vitamin D we take, the harder magnesium has to work, and the faster it will be depleted (mostly because of the effects of vitamin D on calcium absorption), as magnesium goes about the critical job of trying to maintain a "normal" blood level of calcium, in addition to the hundreds of other chemical processes for which magnesium is required in various body systems.
I haven't seen any research on this, but I have a hunch that if a study were done, it would show that virtually everyone who takes a calcium supplement has a magnesium deficiency. And the sad truth is, almost everyone would be better off without any calcium supplements. Chris Kresser apparently agrees with me on this point:
I’ve made the argument before that some supplements may be necessary even within the context of a nutrient-dense, whole-foods diet. Some nutrients are challenging to get through food alone, especially if you’re not digesting food optimally or you’re struggling with a disease that increases your need for particular nutrients. I routinely recommend supplements to many of my patients, and have seen the benefits of proper supplementation in my own life as well.
That said, there are several supplements that are commonly recommended by conventional doctors and healthcare practitioners that are unnecessary at best, and potentially harmful at worst. Perhaps the best example of this is calcium.
Calcium has become extremely popular to supplement with, especially amongst older women, in the hope that it will prevent osteoporosis. We’ve all seen the products on the market aimed at the “worried-well”, such as Viactiv and Caltrate, suggesting that supplementing with calcium can help maintain bone health and prevent osteoporosis, a serious condition affecting at least 10% of American women. (1) Yet the evidence that calcium supplementation strengthens the bones and teeth was never strong to begin with, and has grown weaker with new research published in the past few years. A 2012 analysis of NHANES data found that consuming a high intake of calcium beyond the recommended dietary allowance, typically from supplementation, provided no benefit for hip or lumbar vertebral bone mineral density in older adults. (2) And a 2007 study published in the American Journal of Clinical Nutrition found that calcium supplements don’t reduce fracture rates in older women, and may even increase the rate of hip fractures. (3)
Beyond being ineffective for bone health, calcium supplements are associated with some pretty serious health risks. Studies on the relationship between calcium and cardiovascular disease (CVD) suggest that dietary intake of calcium protects against heart disease, but supplemental calcium may increase the risk. A large study of 24,000 men and women aged 35–64 years published in the British Medical Journal (BMJ) in 2012 found that those who used calcium supplements had a 139% greater risk of heart attack during the 11-year study period, while intake of calcium from food did not increase the risk. (4) A meta-analysis of studies involving more than 12,000 participants also published in BMJ found that calcium supplementation increases the risk of heart attack by 31%, stroke by 20% and death from all causes by 9%. (5)
An analysis involving 12,000 men published in JAMA Internal Medicine found that intakes of over 1,000 mg of supplemental calcium per day (from multivitamins or individual supplements) were associated with a 20% increase in the risk of death from CVD. (6) Researchers suspect that the large burst of calcium in the blood that occurs after supplementation may facilitate the calcification of arteries, whereas calcium obtained from food is absorbed at slower rates and in smaller quantities than from supplements. (7) It is also suspected that extra calcium intake above one’s requirements is not absorbed by bones, but rather excreted in the urine, increasing the risk of calcium kidney stones, or circulated in the blood, where it might attach to atherosclerotic plaques in arteries or heart valves. (8)
https://chriskresser.com/calcium-supple ... ink-twice/
And yes it has long been true that "Some doctors are prescribing 50,000 IU of Vitamin D in the synthetic D2 form instead of the previous standard of 400iu per day." However, Dr. Dean failed to mention that the prescribed dose is typically 50,000 IU per week (not per day as some people might incorrectly assume). And D2 has been shown by published research to be far inferior to D3 for resolving vitamin D deficiencies.
That said, her point is right on target — taking vitamin D can definitely lead to a magnesium deficiency if magnesium is not also supplemented. And this can be critically relevant if a calcium supplement is taken, and/or one's diet contains a lot of calcium.
Thanks for the link.
Tex