What diet causes magnesium deficiency?

October 29, 2025 •

4 min read

According to dietary surveys, nearly half of the U.S. population does not meet the recommended daily intake for magnesium, making it a surprisingly common issue. This widespread insufficiency is often directly tied to the specific dietary choices and habits that contribute to a magnesium deficiency.

Quick Summary

Nutritional patterns rich in processed foods and refined sugars significantly increase the risk of low magnesium levels. Excessive alcohol and caffeine consumption also deplete this vital mineral, as do high-protein diets and certain compounds like phytates and oxalates found in some foods. Certain restrictive diets, if not carefully managed, can also lead to deficiency.

Key Points

Processed and Refined Foods: Diets high in processed foods and refined grains are a primary cause of deficiency, as these foods have been stripped of most of their natural magnesium content.
High Sugar Intake: Consuming too much refined sugar and high-fructose corn syrup depletes magnesium reserves because the body uses it to metabolize sugar and increases its urinary excretion.
Alcohol and Caffeine: Excessive alcohol acts as a diuretic, increasing magnesium loss, while caffeine has a similar but milder effect.
Phytates and Oxalates: Compounds found in healthy plant foods like whole grains, nuts, and spinach can bind to magnesium and reduce its absorption, though benefits of these foods typically outweigh this effect.
Unbalanced Restrictive Diets: Poorly managed diets, such as a restrictive keto or vegan diet, can lead to deficiency if not adequately planned with nutrient-dense alternatives.

The American Diet and Refined Foods

One of the most significant culprits behind magnesium deficiency is the modern Western diet, which is typically low in magnesium-rich whole foods and high in processed items. Magnesium is primarily found in the germ and bran of grains, which are stripped away during the refining process to produce white flour and white rice. As a result, many staple foods become severely depleted of their natural magnesium content. For example, processing can remove 80-97% of the magnesium from grains.

How Refined Sugar Drains Magnesium

Refined sugar is another major dietary factor. Your body requires magnesium to metabolize sugar, so consuming a high-sugar diet forces the body to use its existing magnesium reserves, thereby depleting them. Additionally, high blood sugar levels cause the kidneys to excrete magnesium more rapidly, creating a vicious cycle of depletion. This is particularly relevant for individuals with type 2 diabetes, who have increased urinary excretion of magnesium.

The Impact of Beverages: Alcohol and Caffeine

Your choice of drinks can also play a major role in your magnesium levels. Chronic alcohol consumption is a well-established risk factor for magnesium deficiency. Alcohol acts as a diuretic, increasing the excretion of magnesium through the urine. It also impairs the intestinal absorption of magnesium and is often consumed at the expense of more nutrient-dense food choices.

Caffeine, found in coffee, tea, and energy drinks, is a mild diuretic that can also lead to increased urinary magnesium loss, though the effect is less pronounced in habitual drinkers. For individuals with a pre-existing deficiency or other risk factors, this regular depletion can be a contributing factor.

High Protein Intake

While protein is an essential macronutrient, excessively high-protein diets can increase the excretion of magnesium through the urine. This is especially relevant for those consuming large quantities of animal proteins or protein shakes without balancing their intake with magnesium-rich sources.

Compounds that Inhibit Magnesium Absorption

Certain naturally occurring compounds in some healthy foods can modestly interfere with magnesium absorption. It is important to note that these foods are still highly nutritious, and the overall effect on magnesium is often less concerning than the impact of processed foods.

Phytates (Phytic Acid)

Phytates are found in whole grains, nuts, and legumes. They can bind to minerals like magnesium in the digestive tract, forming an insoluble compound that reduces absorption. Soaking, sprouting, or fermenting these foods can help to neutralize phytic acid and increase mineral bioavailability.

Oxalates (Oxalic Acid)

Oxalates are present in foods like spinach, beets, and nuts. Similar to phytates, they can bind with magnesium, hindering absorption. While spinach is high in oxalates, it is also high in magnesium, and cooking can reduce the oxalate content.

Comparison of Diets and Their Magnesium Impact


Dietary Factor	Impact on Magnesium Levels	Why It Happens
High Processed Foods	Negative	Refining strips magnesium from grains and removes nutrient-dense ingredients.
High Refined Sugar	Negative	Requires magnesium for metabolism and increases urinary excretion.
Excessive Alcohol	Negative	Acts as a diuretic and impairs absorption in the intestines.
Moderate-High Caffeine	Moderately Negative	Mild diuretic effect increases urinary loss, though body may adapt.
Well-Planned Vegan	Positive	Rich in magnesium-dense whole foods like seeds, legumes, and leafy greens.
Unbalanced Keto	Negative	Electrolyte flushing during initial adaptation can deplete magnesium.
Plant-Based Foods with Phytates/Oxalates	Slightly Negative	Can inhibit absorption, but soaking/cooking helps and benefits often outweigh this effect.

The Role of Restrictive and Unbalanced Diets

Restrictive diets, including some versions of the ketogenic (keto) diet and poorly planned vegan diets, can lead to magnesium deficiency if not managed properly. When starting a keto diet, the body flushes electrolytes, including magnesium, during the initial adaptation phase, a phenomenon that contributes to the 'keto flu'. While a well-planned vegan diet can be rich in magnesium sources like seeds and legumes, a poor one may lack sufficient intake due to a limited variety of food.

Other Dietary Antagonists

High Calcium Intake: Consuming very high amounts of calcium, particularly from supplements, can compete with magnesium for absorption. The key is balance, not elimination. Dairy products, for instance, have a high calcium-to-magnesium ratio.
High Zinc Intake: Extremely high doses of zinc supplements can interfere with magnesium absorption.
Phosphoric Acid: Found in carbonated soft drinks, this additive can increase magnesium excretion.
Trans Fats: High intake of unhealthy trans fats, found in fried and processed foods, can reduce magnesium absorption.

Conclusion: Making Smarter Dietary Choices

A significant portion of the population is at risk for magnesium deficiency, and dietary choices are at the heart of this issue. An overreliance on processed foods, refined sugars, and excessive intake of alcohol or caffeine all contribute to lower magnesium levels, either by providing fewer magnesium-rich nutrients or by actively increasing its loss from the body. While some healthy foods contain compounds that inhibit absorption, these are minor factors compared to the widespread issues caused by a poor diet.

To prevent and address a magnesium deficiency, the focus should be on prioritizing a balanced diet rich in whole foods. Integrating plenty of green leafy vegetables, nuts, seeds, legumes, and whole grains is a powerful strategy. For those with restrictive diets or specific health concerns, consulting a healthcare provider or a registered dietitian is crucial. For further details on magnesium's health role, refer to the NIH Health Professional Fact Sheet on Magnesium. By making informed and deliberate choices about what you eat and drink, you can actively work to maintain or restore your body's magnesium balance.

Frequently Asked Questions

The most significant dietary cause is a diet heavy in processed and refined foods. The refining process strips away the magnesium-rich parts of grains, and these nutrient-poor foods replace sources of whole foods in the diet.

Yes, high sugar intake causes magnesium depletion. The body needs magnesium to metabolize sugar, and high blood sugar levels can lead to increased magnesium excretion by the kidneys.

Excessive consumption of alcohol is a known cause of deficiency due to its diuretic effects, which increase urinary magnesium loss. Caffeine is also a mild diuretic that can contribute to depletion, especially in those with already low levels.

Foods containing phytates, such as whole grains and legumes, and oxalates, like spinach and beet greens, can modestly inhibit absorption. However, these foods are also rich in magnesium, and cooking or soaking can reduce these compounds.

On a ketogenic diet, the body initially flushes electrolytes, including magnesium, as it adapts to a low-carb state. This requires careful planning to replenish magnesium through appropriate food sources or supplements.

Yes. While supplements can help, a diet high in processed foods, sugar, and alcohol will still cause ongoing magnesium depletion and may hinder the supplement's effectiveness. Optimizing your diet is a key part of maintaining healthy levels.

Yes, older adults are at a higher risk. This is due to factors such as reduced absorption in the gut with age, increased excretion by the kidneys, and potentially eating less nutrient-dense food.