Magnesium For Bone Health

Overview

Did you know that calcium isn’t the only mineral that is vital for healthy bones?

Magnesium is also essential in maintaining strong bones. It promotes bone health, prevents bone diseases like osteoporosis and osteopenia, and reduces fracture risk.

This article will further elaborate on the importance of magnesium for bone health, how it prevents bone diseases, the best way to consume it, and its potential side effects. 

How does magnesium affect bone health?

The benefits of magnesium for bone health are attributed to the nutrient’s role in modulating the structure and functions of bone. Magnesium is responsible for:

Bone formation

• 60% of the body’s magnesium is present in the bones, and 30% is constantly exchanged with the blood to maintain normal serum magnesium levels
• Magnesium maintains the structure and sturdiness of bones by modulating bone mineralization and aiding in the growth of bone-forming cells^1,2,3
• High dietary magnesium intakes are associated with increased bone mineral density and reduced fracture risk in people assigned male at birth (AMAB), people assigned female at birth (AFAB) (mainly postmenopausal), and the elderly (especially prone to osteoporosis)^4,5

Calcium regulation

• Elevated calcium levels weaken bones and worsen inflammation, which then triggers the progression of osteoporosis and contributes to an increased risk of bone fractures
• Magnesium is a calcium antagonist, thus reducing calcium levels and exerting anti-inflammatory effects^1,5
• A study revealed that a 40 -50% reduction in risk of osteoporotic fractures with high intakes of dietary calcium only occurred when the calcium/magnesium intake ratio was more than 1.7, thus emphasizing the importance of a balance between the two minerals⁶

PTH (Parathyroid hormone) modulation

• PTH is secreted by the parathyroid gland when serum calcium levels are low. High levels of PTH breakdown calcium, resulting bone loss, reduced bone strength, and increased susceptibility to fractures
• Magnesium also stimulates and inhibits the release of PTH at low and extremely-low levels respectively. Magnesium can even decrease PTH despite low levels of calcium. It is also required to stimulate the sensitivity of PTH target organs to hormonal action¹ 

Vitamin D activation

• Vitamin D maintains healthy bones by modulating two key minerals Calcium and Phosphate. The active form of Vitamin D stimulates intestinal absorption of Magnesium and Phosphate, which, in turn, aid in the formation of bones
• Magnesium helps in converting Vitamin D to its active form, since the enzymes needed for the process depend on the mineral. Magnesium levels also affect the receptors Vitamin D has bind to exert its action
• Studies have shown that only magnesium supplementation reduces the resistance to Vitamin D treatment and mortality related to Vitamin D deficiency^1,2

Strengthening of skeletal muscles 

• Age and loss of skeletal muscle mass are risk factors of osteoporosis. Magnesium helps strengthen skeletal muscles, which in turn, prevents falls and fractures^5,7
• A study revealed that high magnesium intake increased skeletal muscle mass and bone density in middle and older-aged people AMAB and people AFAB (mainly post-menopausal people AFAB)⁷

Effects of magnesium deficiency on bone health

• Magnesium deficiency increases fracture risk in people with osteoporosis (mainly post-menopausal people AFAB) due to the formation of brittle bones and loss of bone strength²
• It results in inflammation and oxidative stress that causes the breakdown of bone and subsequent bone loss³
• Magnesium deficiency, in turn, causes calcium deficiency, which then affects the activity of Vitamin D, thus causing vitamin resistance¹
• Magnesium deficiency directly decreases Vitamin D levels or indirectly decreases it by hindering the action of PTH at target organs, which causes a decrease in serum Vitamin D levels
• Deficiency also increases PTH levels, thus resulting in bone loss due to the breakdown of calcium²

How much magnesium should I take for bone health?

Studies have shown that elderly and young people consuming less than the recommended daily magnesium dose have lower bone density and are more prone to fractures. Conversely, studies have revealed that people, mainly people AFAB, taking the recommended daily dose had a reduced fracture risk and increased bone density.³

According to the NHS, the recommended daily dietary magnesium intake is:

• 300 mg for people AMAB (19 to 64 years)
• 270 mg for people AFAB aged (19 to 64 years) (NHS Magnesium)

Some studies showed an increase in bone density with magnesium intakes that exceeded  the recommended dose.^1,3

Possible reasons for consuming slightly high doses of magnesium are age-related differences in magnesium intake (the elderly require slightly more magnesium for bone health) and different dietary standards used.^1,3,4 

Another one could be compensation for interactions that affect its absorption. In healthy individuals, about 30-70% of dietary magnesium is absorbed by the intestines.² 

However, food, other nutrients, and certain drugs can affect its levels in the body. Phytates, oxalates, calcium intake over 10 mg/kg/day, phosphorus, zinc, aluminium, alcoholic beverages, and coffee interfere with and reduce the intestinal absorption of magnesium. While drugs like diuretics, insulin, and digitalis alter the balance of magnesium in the body.^1,3

But regardless of the reason, it’s best to follow the dietary standard and not go overboard since a long-term intake of high doses of magnesium can have adverse effects on the body.^1,8

Which magnesium is best for bone health?

Many studies have used various types of magnesium supplements in addition to dietary magnesium to prove that magnesium supplementation promotes bone health and alleviates osteoporosis.^1,3,4,5,6,7

Research has shown that magnesium citrate, aspartate, chloride, and lactate (organic salts) are better absorbed by the body than magnesium oxide and magnesium sulphate (inorganic salts).¹

A study suggested that daily supplementation of 200 mg magnesium citrate or lactate is safe, effective, and adequate to achieve normal serum magnesium levels in 20-40 weeks.¹ However, another revealed that 300 mg of magnesium oxide per day increased hip bone mineral content.³ 

Research has also revealed the beneficial effects of the combined use of magnesium supplements, calcium supplements, and vitamins. One study using magnesium citrate and oxide along with calcium carbonate and Vitamin D3 reported an increase in bone density in adolescents AFAB. Another study using magnesium and potassium together saw a decrease in hip fracture risk in people AMAB and AFAB.³

It’s also important to note that the beneficial effects of magnesium supplements are more profound on the elderly and alcoholics than on athletes and active adults.¹

Besides dietary supplements, natural sources of magnesium also help raise low magnesium levels in the body. The type of foods that reduce the risk of osteoporosis can be found here.

Side effects and other concerns

There are no side effects of higher dietary magnesium intake since the body stabilises serum magnesium levels by reducing its intestinal absorption and increasing its renal excretion. 

However, this only applies to healthy individuals without renal impairments since the kidneys are responsible for expelling the excess magnesium out of the body.¹

Unlike dietary magnesium, high intakes of magnesium supplements and drugs (more than 400 mg/day) cause:

• Diarrhoea
• Nausea
• Abdominal cramps¹

Prolonged use of these medications, especially magnesium-containing antacids and laxatives, causes a rare, but serious condition called hypermagnesemia. 

Its hallmark is elevated serum magnesium levels, and it can be fatal if not treated quickly. It mainly occurs in elderly patients with kidney problems, especially in cases of renal failure. 

The normal serum magnesium levels are 1.7 – 2.4 mg/dL, but even values under 4 mg/dL are generally well tolerated. However, magnesium levels crossing 7 mg/dL cause hypermagnesemia symptoms to manifest.⁸

There are three stages of hypermagnesemia:

Mild hypermagnesemia (less than 7 mg/dl) 

• Asymptomatic 

Or

• Nausea

Dizziness

• Confusion
• Weakness

Moderate hypermagnesemia (7-12 mg/dl) 

• Headaches
• Constipation
• Bladder paralysis (lack of bladder control)
• Increased confusion and weakness
• Impaired reflexes
• Bradycardia (slow heart rate)
• Blurred vision

Severe hypermagnesemia (more than 12 mg/dl) 

• Muscle paralysis and weakness
• Respiratory paralysis (weakness of respiratory muscles)
• Hypotension (low blood pressure)
• Bradycardia
• Lethargy⁸

Serum magnesium levels above 15 mg/dl can result in coma and cardiorespiratory arrest. But toxic hypermagnesemia only occurs at oral magnesium doses exceeding 2500 mg.¹

Summary

Magnesium is an essential nutrient vital for many bodily functions. It maintains bone health by modulating bone formation, regulating calcium and parathyroid hormone levels, activating Vitamin D, and strengthening skeletal muscles.

Magnesium deficiency is implicated in osteoporosis, reduced bone mineral density, bone loss, and fractures. Thus, higher magnesium intake can prevent and alleviate these conditions, especially in elderly and postmenopausal people assigned female at birth (AFAB), since they are at higher risk.

However, instead of consuming magnesium alone, it’s better to incorporate calcium and Vitamin D as well for a more profound and holistic approach to improving bone health. 

It’s also important to stick to the recommended intake and not go overboard since high doses of magnesium have side effects that worsen with underlying kidney problems.