The Importance of the Magnesium and Calcium Relationship: A Key Ratio for Health
The magnesium and calcium relationship is an important underlying concept of The Paleo Diet and Dr. Loren Cordain’s thirty years of nutrition research. In fact, the calcium-to-magnesium ratio is a key reason that dairy products are not Paleo foods. Unfortunately, 1970s-era government-backed daily nutrition guidelines that were intended to address osteoporosis got the nutrition science wrong and missed a key point; the ratio of magnesium and calcium matters far more than total calcium for bone health. Most people get too much calcium and not enough magnesium. Worse yet, too much calcium (or not enough magnesium) can cause many chronic health problems including heart disease, cancer risk, insulin resistance, and inflammation.
We need calcium. No one is going to dispute that fact. Calcium is the most abundant mineral in our bodies, critical to bone health and muscle function. (1,2) Without adequate calcium we could not survive. So, it is no wonder that for several decades, the need for calcium (either through diet or supplementation) has been promoted for good health—from milk moustache advertisements touting strong bones to osteoporotic women being told to supplement by their doctors.
The result of this increased awareness is that daily calcium intake nearly doubled in women from 1977 to 2011. Much of that increase was due to supplementation. (3)
So, what impact did this awareness have on health? The increased calcium consumption, particularly from milk, has been associated with a higher risk of heart disease, cancer, insulin resistance, inflammation, and all-cause mortality. (4–11) And while many are increasing their calcium intake to strengthen their bones, evidence that higher calcium consumption prevents bone degeneration or factures is limited and sometimes contradictory. (7,12)
Does this evidence suggest that calcium is actually bad for us? Of course not. Calcium is essential for life. But as with all things in nutrition, it’s not a simple matter of “more is better.” This is best summarized by a 2018 concept paper in the highly respected journal Nutrients:
[This] goes beyond the classical approach of evaluating each micro or macro nutrient by itself; which may be a relic of the past when deficiency type studies dominated… Micronutrient ratios may confer more comprehensive information than the concentration of a single nutrient… This suggests that the underlying issue is a disruption in the ratios of micronutrients in the Western diet. (13)
Which brings us to the calcium-to-magnesium ratio. What may be more important than the absolute quantity of calcium in the diet, or magnesium for that matter, is a healthy ratio of the two.
Most People Get More Than Enough Calcium And Not Enough Magnesium
The same 2018 paper showed, using NHANES data, that men over the age of 50 consumed 1,589 mg/d of calcium compared to the recommendation of 1,000 mg/d, while women over 50 consumed 1,177 mg/d compared to the 1,200 mg/d recommended.
In short, looking purely at their calcium intake, the subjects were getting enough. Yet, in the general population, osteoporosis has been on the rise. So, there is more to this issue than the absolute quantity of calcium.
Which brings us to the magnesium and calcium relationship. What may be more important than the absolute quantity of calcium in the diet, or magnesium for that matter, is a healthy ratio of the two. In the same period from 1977 to 2011, the ratio in women increased from approximately 2.6-to-1 up to 3.7-to-1. This is illustrated in Figure 1 below:
Extensive research on the subject has shown that a ratio of approximately 2-to-1 calcium-to-magnesium ratio is considered healthy, while ratios above 2.6-to-1 and below 2-to-1 can lead to heart disease and other conditions. (3,14) Several recent studies showed decreased mortality rates when magnesium intake was increased by 200 mg/d or more in subjects with a 3-to-1 or higher ratio. (15–17)
The importance of a healthy magnesium and calcium relationship may explain the contradictory results seen in research studies that only looked at calcium concentrations. High, low, and recommended calcium consumption has been inconsistently shown to contribute to heart disease. The results may have more to do with the calcium-to-magnesium ratio, as explained in the 2016 review by Rosanoff et al.:
Dietary intake studies of either magnesium or calcium alone may be unwittingly confounded by the unmeasured calcium or magnesium… it appears that too much or too little of either calcium or magnesium might not be beneficial and there may be an optimal range of human calcium and magnesium intake. (3)
In the United States, the average calcium-to-magnesium ratio is above 3-to-1 and frequently higher in women. In Japan, the ratio is below 1.7-to-1. Both levels are considered unhealthy. (3)
Why More Calcium—Without More Magnesium—Is Dangerous for Health
In an effort to stop rising osteoporosis rates in North America, as previously mentioned, calcium RDAs were increased in women to 1,200 mg/d. Other recommendations have even taken it higher to 1,300 mg/d. Calcium is the only RDA where the recommendation is higher for women than for men. See the National Institutes of Health U.S. RDA tables.
There are several problems with this strategy. First, there are risks associated with increasing calcium intake in isolation. Two recent studies in BMJ demonstrated this risk. The first, a 2010 meta-analysis of 26 studies, clearly showed that calcium supplementation increases the risk of both heart attacks and sudden death. (8)
The second, a 2013 cohort study of over 61,000 women, found that high calcium intake increased the death rates from all-cause mortality in women. (6) However, conversely, a 2011 randomized controlled trial found that calcium supplementation in women over 70 did not find an increased risk of vascular disease. (18)
The second problem with increasing calcium in isolation is that it is nearly impossible to achieve these RDAs for calcium on a natural diet without either consuming dairy or supplementing. (5)
Dr. Cordain has written extensively about milk and how it contributes to a host of health issues including heart disease, acne, cancer, and insulin resistance. (4) In short, dairy has a calcium-to-magnesium ratio of around 12-to-1, which is the highest of any food we eat. So, drinking milk regularly may help you meet the RDAs for calcium, but it is only going to push this critical ratio into more unhealthy ranges.
In fact, a 1993 study by Dr. Artaud-Wild et. al, found that milk and its components (including calcium) had the highest relationship with cardiovascular death rates of any food examined. (19)
You may be following your doctor’s advice by consuming more milk and supplementing with calcium, but without proportionally increasing your magnesium consumption, the results could be devastating. And this is a concern because it appears that over 50 percent of Westerners get inadequate magnesium. (3)
The Optimal Calcium-to-Magnesium Ratio
Americans do not get sufficient magnesium. Furthermore, the typical Western diet has a calcium-to-magnesium ratio above 3-to-1. (3) The solution for most of us is to increase magnesium consumption.
That raises the question: How much more magnesium do we need? Unfortunately, that’s difficult to answer. Our bodies maintain a very tight magnesium concentration in our blood. If we do not eat enough, our bodies will sacrifice bone and intracellular stores in order to maintain plasma levels. As a result, people can be magnesium deficient while still having normal serum levels—a condition called “chronic latent magnesium deficit” or CLMD. (3)
Unfortunately, simply supplementing with magnesium is often not a solution. It’s important to get a ratio of calcium-to-magnesium around 2-to-1. Straying too high or too low from that ratio is unhealthy. But since most people don’t know how much calcium or magnesium they are getting in their diet and there isn’t a good blood test to determine our magnesium levels, it’s hard to know how much to supplement. Furthermore, according to Rosanoff et. al., adults who supplemented with magnesium overcompensated with calcium and made their calcium-to-magnesium ratio worse. (3)
Ultimately the best solution is through a natural diet. (26) Analyses of hunter-gatherer diets have shown that daily intake approximated the optimal ratio of 2-to-1. (14)
Since, for most North Americans, the issue is bringing down the ratio below 3-to-1, eating fruits, vegetables, and nuts (such as almonds), which are high in magnesium, can help you get adequate magnesium in your diet while also ensuring you obtain the calcium you need for an optimal ratio and good bone health.
Dr. Loren Cordain created the following two tables of fruits and vegetables showing their calcium-to-magnesium ratios as a guide.
Common Vegetables and Their Mg and Ca Content
TABLE 1: calcium and magnesium content and calcium-to-magnesium ratio of common vegetables sorted by ratio
|Sweet potato leaves||61.0||37.0||0.61|
|New Zealand Spinach||39.0||58.0||1.49|
|Butterhead (Bibb) lettuce||13.0||35.0||2.69|
|Lettuce, red leaf||12||33||2.75|
|Loose leaf (Green Leaf) lettuce||13.0||36.0||2.77|
|Rapini (Broccoli Raab)||22.0||108.0||4.91|
|Napa (Chinese) cabbage||13||77.0||5.92|
|Bok Choi (Chinese cabbage)||11||68.8||6.26|
|Nopales (cactus leaves)||22.0||164.0||7.46|
Common Fruits and Their Mg and Ca Content
TABLE 2: calcium and magnesium content and calcium-to-magnesium ratio of common fruits sorted by ratio
|Grapes (Red or Green)||7||10||1.43|
Remember that it’s not the ratio of any one particular food, but the overall ratio of your daily diet that’s important. That said, making sure you eat foods with a low ratio to balance foods with a high ratio will help keep you in a healthy range.
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Trevor Connor, M.S.
Dr. Loren Cordain’s final graduate student, Trevor Connor, M.S., brings more than a decade of nutrition and physiology expertise to spearhead the new Paleo Diet team.More About The Author