You show up for your blood work like any of your other appointments with your oncologist, but this time your doctor says “your magnesium is low.” If your like most people you stop and wonder what this means and ask how you can fix it. You can’t help but wonder if it was something you may have done or not done.

Magnesium is lost when someone has had vomiting or diarrhea, which can be common with some cancer treatments like the chemo Cisplatin, radiation to certain locations like to the stomach or small or large intestines, and even surgery to certain areas like the stomach or bowel. A magnesium deficiency can also result from inadequate food intake, chronic alcoholism, drinking too much caffeine consistently, and other conditions like IBS, Crohn’s disease, Celiac’s disease, diabetes, and stomach viruses.

Why is magnesium important?

Magnesium is an essential mineral and electrolyte that your body needs in order to function properly. It helps to regulate your blood sugar, produce energy, is vital for contracting and relaxing your muscles, and is responsible for chemical reactions in your body. Magnesium also helps to maintain the proper levels of other minerals like calcium, potassium, and zinc. Perhaps its most noteworthy job is helping your heart, muscles, and kidneys work properly, and helps to build teeth and bones.

How much magnesium do you need per day?

If your magnesium is low, doctors will sometimes prescribe a magnesium supplement and recommend eating more magnesium-rich foods depending on your results. The doses of the supplements may be different depending on your labs, but generally speaking healthy female adults need to get about 310-320 milligrams (mg) of magnesium and male adults need about 400-420 mg a day from foods. When magnesium losses are increased, eating foods that are good sources of magnesium can help keep the levels of magnesium in your blood in a healthy range, but this may not increase as fast as taking a supplement. If you are at risk for having low levels longer-term, then focusing on magnesium-rich foods may be key.

Foods high in magnesium

There are many good natural food sources of magnesium, with the best sources being legumes, nuts, whole grains and certain vegetables. You can include them more often if you have been advised to eat more magnesium-rich foods by your health care team. These foods have up to 80 mg of magnesium per serving. For more on specific amounts you can check out the USDA Nutrient Database here.


Artichokes, avocados, beet greens, okra, baked potatoes with the skin, spinach, Swiss chard, sweet potato, pumpkin, squash, tomato sauce

Whole grains

Whole grain cereals, whole grain breads, wheat germ, rice, oatmeal, whole wheat pasta


Peanut butter, all nuts and seeds, quinoa


Soy milk, yogurt, eggnog, milk


All beans and legumes, tofu, edamame


Dark and milk chocolate, prune juice

Tips for Taking Potassium Supplements

If your doctor prescribes magnesium supplements, you should take them as directed. Magnesium in dietary supplements and meds should not be consumed in amounts above the upper limit, unless recommended by a healthcare provider.

Take-home message

You can always ask your doctor or medical care team if you are at risk for low levels of magnesium with your current cancer treatment regimen so that you can better prepare. The good news is that most people need to be eating more whole grains, beans, and veggies anyway since most of us aren’t getting enough magnesium in our diets. This also helps you meet your fiber intake each day. Magnesium content that is present in foods naturally doesn’t need to be limited unless otherwise specified by your doctor. Try incorporating more of these foods into your diet to get a magnesium boost.

This post originally appeared on Survivors’ Table. It is republished with permission.