Magnesium: Health Benefits, Facts, Research
Reviewed by Debra Rose Wilson, PhD, MSN, RN,
IBCLC, AHN-BC, CHT
Magnesium plays an
important role in over 300 enzymatic reactions within the body including the
metabolism of food, synthesis of fatty acids and proteins, and the transmission
of nerve impulses.
Magnesium is one of the seven essential
macrominerals; these are minerals that need to be consumed in relatively large
amounts – at least 100 milligrams per day.
The human body contains approximately 25 grams of
magnesium. Over 50 percent of that magnesium is stored in the skeletal system,
and the rest is found in muscle, soft tissues, and bodily fluids.
Magnesium deficiency, especially prevalent in
older populations, is linked to insulin resistance, metabolic
syndrome, coronary heart
disease, and osteoporosis.
This MNT Knowledge Center
feature is part of a collection of articles on the health benefits of key vitamins and minerals. It provides an in-depth
look at recommended intake of magnesium, its effects on health, foods high in
magnesium, and any potential health risks of consuming too much magnesium.
Contents of this
article:
Fast facts on magnesium
Here are some key points about magnesium. More
detail and supporting information is in the main article.
·
Magnesium is vital for
the proper functioning of hundreds of enzymes
·
Consuming adequate
magnesium might help reduce premenstrual symptoms
·
For adult males, the
recommended daily allowance of magnesium is 400-420 milligrams
·
Sunflower seeds,
almonds, and shrimp are some of the foods high in magnesium
Possible health
benefits of magnesium
Magnesium supplements are available from
stores, but it is best to obtain it through food.
The following health benefits have been
associated with magnesium.
1) Bone health
Magnesium is important for bone formation; it
helps with the assimilation of calcium into bone and plays a role in
activating vitamin D in
the kidneys (vitamin
D is also essential for healthy bones).
Optimal magnesium intake is associated with
greater bone density and improved bone crystal formation, as well as a lower risk of osteoporosis in
postmenopausal women.
2) Diabetes
Magnesium plays an important role
in carbohydrate and glucose metabolism, so it is no wonder magnesium
status has an effect on diabetes.
Several studies have confirmed the
inverse relationship between magnesium intake and the risk of diabetes. For
every 100 milligrams per day increase in magnesium intake (up to a point), the
risk of developing type 2 diabetes decreases by approximately 15
percent.
Most magnesium intake in these studies was
from dietary sources, not supplements. Clinical studies have shown improvement
in insulin sensitivity with a magnesium supplement intake of
between 300 and 365 milligrams per
day.
Researchers were also able to show that low
magnesium levels resulted in impaired insulinsecretion
and lower insulin sensitivity.
3) Heart health
Magnesium is necessary to maintain the health
of muscles, including the heart, and for the transmission of electrical signals
in the body. Adequate magnesium intake has been associated with a lower risk of atherosclerosis (fatty
buildup on the walls of arteries) and hypertension (high blood pressure).
More recently, several studies have found that
a high intake of calcium without
sufficient magnesium could increase the risk of arterial calcification and
cardiovascular disease, as well as kidney stones.
In the Framingham Heart Study, people with the
highest intake of magnesium were found to have a 58 percent lower chance of having
coronary artery calcification and a 34 percent lower chance of abdominal artery
calcification.
Rapid post-heart attack administration of
magnesium reduces the risk of mortality, and magnesium is sometimes used as
part of the treatment for congestive heart failure in order to lessen
the risk of arrhythmia (abnormal heart rhythm).
Improvement in lipid profiles has been seen
with an intake of 365 milligrams of magnesium per day.
4) Premenstrual
syndrome
Research suggests that people experiencing
premenstrual syndrome may be able to alleviate symptoms such as
bloating, insomnia,
leg swelling, weight gain, and breast tenderness by ensuring adequate intake of
magnesium. Magnesium combined with vitamin B6 appears to be more effective.
5) Relieving
anxiety
Reductions in magnesium, or alterations in the
way that it is processed have been found to increase levels of anxiety.
This appears to be through activity in the hypothalamic-pituitary-adrenal (HPA)
axis – a set of three glands that controls our reaction to stress.
Research has shown that a low-magnesium
diet alters the types of bacteria present in
the gut and alters anxiety-based behavior.
Recommended
magnesium intake
The Recommended Daily Allowance (RDA) for
magnesium depends on age and gender. The National Institutes of Health recommend
that children 1-3 years of age get 80 milligrams of magnesium a day, rising to
130 milligrams for children aged 4-8, and 240 milligrams for children aged
9-13.
After the age of 14, RDAs diverge for men and
women, with men typically requiring more magnesium than women due to a larger
average body mass. At the age of 14-18, the RDA for males is 410 milligrams,
and 360 milligrams for females.
Adult females are advised to get 310-320
milligrams per day. An RDA of 350-400 milligrams is advised during pregnancy,
and 310-360 milligrams when breastfeeding.
The RDA of magnesium for adult males is
400-420 milligrams.
The “bioavailability” of a nutrient
refers to the degree to which it is absorbed and retained in the body for use.
Magnesium has a medium level bioavailability; it is predominantly absorbed by
the small intestine, with the efficiency of absorption depending on the amount
of magnesium in the diet, the health of the gastrointestinal tract, the overall
magnesium status of a person, and their diet as a whole. Unabsorbed magnesium
is excreted in the feces.
Magnesium supplements are available, but it is
best to obtain any vitamin or mineral through food as this increases the
likelihood of ingesting optimal levels of other required and beneficial
nutrients.
Many vitamins, minerals, and phytonutrients
work synergistically, in other words, their benefits for health, when taken
together, are greater than simply the sum of their individual benefits. As
such, it is recommended to focus on meeting daily requirements for magnesium
from foods before resorting to supplements as a backup.
Foods high in
magnesium
Magnesium is found in a wide variety of foods,
such as green leafy vegetables, nuts, seeds, brown rice, meat, and dairy.
The best sources of
magnesium are nuts and seeds, dark green vegetables, whole grains, and legumes.
Magnesium is also added to some breakfast cereals and other fortified foods.
·
Sunflower seeds, dry
roasted, 1/4 cup: 128 milligrams
·
Almonds, dry-roasted,
1/4 cup: 105 milligrams
·
Sesame seeds, roasted
whole, 1 ounce: 101 milligrams
·
Spinach, boiled, 1
cup: 78 milligrams
·
Cashews, dry-roasted,
1 ounce: 74 milligrams
·
Shredded wheat cereal,
two large biscuits: 61 milligrams
·
Soymilk, plain, 1 cup:
61 milligrams
·
Black beans, cooked,
1/2 cup: 60 milligrams
·
Oatmeal, cooked, 1
cup: 58 milligrams
·
Broccoli, cooked, 1
cup: 51 milligrams
·
Edamame, shelled, cooked, 1/2 cup: 50
milligrams
·
Peanut butter, smooth,
2 tablespoons: 49 milligrams
·
Shrimp, raw, 4 ounces:
48 milligrams
·
Black-eyed peas,
cooked, 1/2 cup: 46 milligrams
·
Brown rice, cooked,
1/2 cup: 42 milligrams
·
Kidney beans, canned,
1/2 cup: 35 milligrams
·
Cow’s milk, whole, 1
cup: 33 milligrams
·
Banana,
one medium: 33 milligrams
·
Bread, whole-wheat,
one slice: 23 milligrams
Magnesium is lost during the refinement
process of wheat, so it is best to opt for cereals and bread products made with
whole grains. Most common fruits, meat, and fish, are low in magnesium.
Possible health
risks of consuming magnesium
Large doses of magnesium can cause a loss
of central nervous system control. People with renal (kidney)
insufficiency should not take magnesium supplements unless advised to do so by
their physician.
No cases of magnesium toxicity from food
intake have ever been reported, and such an occurrence seems highly unlikely to
arise in any normal diet. However, if you are considering taking a supplement,
there are certain drug interactions that people should be aware of.
Individuals taking any of the following medications should
discuss magnesium supplements with their doctor before taking them:
·
Dabrafenib
·
Digoxin
·
Eltrombopag
·
Elvitegravir
·
Gefitinib
·
Ketoconazole
·
Ledipasvir
·
Levomethadyl
·
Licorice
·
Mycophenolate Mofetil
·
Mycophenolic Acid
·
Pazopanib
·
Phenytoin
·
Quinine
·
Raltegravir
·
Rilpivirine
·
Vismodegib
It is the total diet or overall eating pattern
that is most important in disease prevention and achieving good health. It is
better to eat a diet with a variety than to concentrate on individual nutrients
as the key to good health.
