Magnesium may or may not help prevent muscle cramps. Here’s why.
Magnesium may or may not help prevent muscle cramps. Here’s why.
References:
Magnesium for muscle cramps | Cochrane
Hello and welcome to the Nutrition Diva podcast, a show where we take a closer look at nutrition research, trends, and claims, so that you can feel more confident about your food and nutrition choices. I’m your host, Monica Reinagel, and today I want to talk about the role of magnesium in preventing muscle cramps.
On the one hand, a Cochrane review of the literature found that magnesium supplements were no better than placebos in reducing cramp frequency or severity. The Cochrane Review process is highly regarded in the scientific community for its rigor and reliability. On the other hand, a lot of people (including my very own Mom) are convinced that taking a magnesium supplement helps to ward-off nighttime muscle cramps.
But I think a closer look at both the problem of muscle cramps and the evidence on magnesium can help us reconcile these seemingly contradictory positions–and help you decide whether or not to try it.
First, not all muscle cramps are the same. Exercise-associated muscle cramps (EAMC), as the name implies, are frequently experienced by runners and other professional and recreational athletes. But muscle cramps are also more common in older individuals, a phenomenon known as idiopathic cramping. Let’s tackle these one at a time, starting with EAMC.
Traditionally, EAMC were thought to be caused by electrolyte imbalance and dehydration. However, recent research has cast some doubt about this. Acute electrolyte status does not reliably predict who will or will not get cramps. Despite proper hydration and electrolyte supplementation, many athletes still experience muscle cramps, suggesting that there are other factors at play.
Other research suggests that EAMCs are more likely caused by muscular fatigue and changes in nervous system excitability, rather than by simple electrolyte depletion. This "altered neuromuscular control" hypothesis suggests that when muscles get fatigued, it creates an imbalance in the nerve impulses that control the muscles–too much contracting, not enough relaxing–and this can result in cramps.
Now it is true that dehydration and electrolyte depletion can cause muscles to fatigue more readily, and fatigued muscles are more likely to cramp. So, there is an indirect connection. But muscle cramps tend to be more related to the intensity and duration of exercise than to the levels of electrolytes or hydration
Here’s the bottom line for athletes: Maintaining good hydration and electrolyte balance is still going to benefit overall health and performance. And if you exercise a lot, your requirement for magnesium and other electrolyte minerals may be a bit higher due to perspiration losses
But the specific role of electrolytes in preventing EAMCs might be less significant than previously thought. Instead, avoiding over-training and allowing adequate recovery might be more effective strategies for preventing muscle cramps.
As I mentioned earlier, muscle cramps can also occur in people who are not athletes, especially as we get older. Here, the cause is more likely to be underuse, not overuse of muscles.
A more sedentary lifestyle can cause muscles to atrophy, which makes them easier to fatigue and more susceptible to cramps. Without regular stretching and movement, muscles and tendons can also become tight and shortened. This decreased flexibility can increase the likelihood of muscle cramps, as tight muscles are more prone to spasms when suddenly contracted.
Inactivity can also lead to a decline in neuromuscular function, which can result in an imbalance in the signals to the muscles, causing involuntary muscle contractions or cramps. Interestingly, this is similar to the mechanism that can lead to cramps in athletes who are overtraining. Only in this case, the problem is not too much exercise but too little. And the solution is not more recovery time, but more active time. (Mom, are you listening?)
Older folks are also more likely to have low dietary magnesium intake or to be taking medications that affect magnesium levels. And some research indicates that people with lower baseline magnesium levels might experience more frequent or severe muscle cramps. This may help to explain why magnesium supplements seem to help some, but not others.
If an individual is not particularly low in magnesium, or the muscle cramps are primarily due to over- or under-use of the muscles, taking extra magnesium may not be as likely to help. But, to the extent that low magnesium levels–whether that’s due to low dietary intake or excessive perspiration loss–are contributing to the problem, getting more magnesium could help.
In fact, six out of ten Americans don't get the recommended amount of magnesium each day. And adults over the age of 50 are even more likely to fall short. Fortunately, magnesium is not that hard to come by. It's found in a wide variety of whole foods, including fruits, vegetables, nuts, seeds, and whole grains. Low magnesium intake is really a marker for diets that are high in processed foods.
Green vegetables are great sources of dietary magnesium because this mineral is part of the chlorophyll molecule that gives plants their green color. If you are eating the recommended five servings of vegetables a day, that's a third of your requirement right there. Vegetables that are particularly high in magnesium include broccoli, Swiss chard, and green beans.
Magnesium is also naturally present in whole grains. but it's one of the nutrients that gets stripped away when grains are refined. A cup of brown rice, for example, supplies a quarter of your daily requirement. A cup of white rice provides only about 2% of your daily needs. Bran cereals are also particularly good sources of magnesium.
Nuts and seeds are rich in magnesium, as well. Brazil nuts and sunflower seeds are particularly good sources. But, on average, you can count on getting about 20% of your daily magnesium requirement from a one-ounce serving of any nut or seed.
Legumes, such as lentils, soybeans, lima beans, and all kinds of dried beans, are all good magnesium sources, providing about 20% of your daily needs per serving.
The foods that are rich in magnesium are high in lots of other nutrients, as well. Including more of these foods in your diet will improve your overall nutrition, not just your magnesium status. So rather than just pop a nutritional supplement, increasing our consumption of whole foods is by far the best way to increase magnesium intake, and may help to ward off the dreaded muscle cramps.
Finally, if you are plagued by muscle cramps and a supplement seems to help, well, who cares what the Cochrane Review thinks? Magnesium supplements are relatively safe and inexpensive. However, like any supplement, you should be aware of potential side effects and interactions.
Some forms of magnesium, including magnesium oxide and magnesium citrate, can have a laxative effect. (This is often seen as a feature, not a bug.) Magnesium can interact with certain medications so definitely check in with your pharmacist regarding any regular medications that you take. People with impaired kidney function should be especially cautious.
That's all for this episode. I hope you got some useful takeaways from it. If you have a question you'd like me to answer, you can email me at nutrition@quickanddirtytips.com. I’d be happy to add it to my queue for future episodes.
Nutrition Diva is a Quick and Dirty Tips podcast and is supported by a fantastic team, which includes Brannan Goetschius, Nathan Semes, Davina Tomlin, Holly Hutchings, Morgan Christianson, and Kamryn Lacy.