Magnesium RDA and Its Impact on Aging

By: Michael Lam, MD, MPH

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Magnesium RDA How Much is Enough?

Magnesium RDA impacts your bonesThe National Research Council recommended minimum daily consumption for Magnesium RDA is 150 – 250 mg for children under 10 years of age, and 300 – 400 mg for adults. Current statistics show that only 25% of surveyed populations meet or exceed the Magnesium RDA. Almost 40% consume less than 70% of the RDA. It is fair to say that the majority of the North American population has a sub-optimal intake of magnesium.

Magnesium RDA is about 2 mg per pound body weight. The American diet typically provides 1.2 – 1.5 mg per pound of body weight. Many magnesium experts believe that an intake range of 2.7 – 4.5 mg per pound (about 400 – 700 mg a day) is optimal. Some on the forefront of Magnesium RDA research are recommending up to 1000 mg per day for healthy people, using the clinical symptom of diarrhea as a target marker. Once the marker is achieved, magnesium intake can be reduced. Asians, for example, are already taking 3 – 4.5 mg of magnesium per pound of body weight

Common Symptoms

  1. Musculo-Skeletal Symptoms: osteoporosis, chronic fatigue and weakness, muscle spasms, tics, tremors, and restlessness.
  2. Cardiovascular Symptoms: atherosclerosis, cardiac arrhythmias, sudden death, and vasospasms.
  3. Female Issues: PMS (Premenstrual Syndrome) and eclampsia.
  4. Psychiatric Symptoms: irritability, depression, and bipolar disorders.
  5. Neurological Symptoms: migraine headaches, excessive noise and pain sensitivity.
  6. Endocrine Symptoms: insulin resistance.

Clinical Uses of Magnesium

A. Prevention and Management of Primary Postmenopausal Osteoporosis (PPMO)

The use of calcium supplementation for the management of Primary Postmenopausal Osteoporosis (PPMO) has increased significantly since 1987, the year when the National Institute of Health increased their recommended daily intake of calcium to 1,500 mg for prevention of PPMO. This recommendation was made in spite of the different conclusions made by some clinical studies presented in the same proceedings. Results of some of these controlled studies presented showed no significant effect of calcium intake on mineral density on trabecular bone and only a slight effect on cortical bone. Since PPMO is predominately due to demineralization of trabecular bone, there is no justification for calcium mega-dosing in post-menopausal women. In fact, soft tissue calcification can be a serious risk factor during calcium mega-dosing under certain conditions. Certain investigators, notably Dr. Guy Abraham, postulated that a total dietary program emphasizing magnesium instead of calcium for the management of PPMO would be more effective for preventing bone loss. His concerns about low magnesium for osteoporosis are similar to his concerns for women with premenstrual tension syndrome.

Diet and magnesium RDATo test Dr. Abraham’s hypothesis, 19 postmenopausal women on hormonal replacement were given a supplement consisting of 500 mg calcium (50% of RDA) and 600 mg of magnesium (200% of RDA). Serial bone density studies were conducted every 3 months. Subjects receiving the treatment showed an 11% increase in mean bone density versus 0.7% in the untreated group. Results also showed that in postmenopausal women on hormonal replacement therapy, the magnesium emphasized program resulted in a calcaneous bone density 16 times greater than that of dietary advice alone. At the start of the study, 15 subjects were below the fracture threshold. After a year of treatment with magnesium supplementation, only 7 of them were below the fracture threshold.

Researchers such as Dr. Abraham further postulate that PPMO is predominately a skeletal manifestation of chronic magnesium deficiency, facilitated by estrogen withdrawal during the postmenopausal period. He suggested raising magnesium RDA to 1000 mg/day and lowering the RDA for calcium to 500 mg/day. His proposed daily intake for calcium would be more in line with the World health Organization’s “practical allowance” of 400 – 500 mg daily for adults. Such a reversal of the magnesium/calcium ratio would most probably lower the incidence and prevalence of many other degenerative diseases as well.

B. Prevention of Cardiovascular Diseases (CVD)

Cardiovascular diseases have been often linked to magnesium depletion. One of the most alarming trends in the past half-century is the sharp increase in sudden deaths from ischemic heart diseases, particularly in middle-aged men who suddenly develop myocardial infarction, cardiac arrhythmia, or cardiac arrest. It has been postulated that magnesium deficiency may be a common etiologic factor.

Magnesium is found in high amounts in nuts like almonds and peanuts. Research has found than nut lovers (those who eat nuts 5 times a week) have half the chance of developing a heart attack compared to those who eat nuts only once a week.

Epidemiological studies provide compelling evidence. The lower death rates from coronary heart diseases (CHD) in Japan, China, India, and Italy versus those in Europe and America point to differences in cholesterol and saturated fat consumption as being the primary causative factor.

Not to be forgotten, and perhaps even more critical, is the role of dietary salt in contributing to these differences in death rate. In countries with lower CHD death rates, most of the magnesium comes from table salt that is derived from seawater through an evaporative process. This type of table salt contains calcium, potassium, and large amounts of magnesium, in addition to the sodium. Table salt used by North Americans comes primarily from salt mines. As a result of being washed with hydrochloric acid and recrystallization, this purified salt contains almost pure sodium chloride. The Japanese consume 10 grams of ocean salt a day. This provides approximately 1500 mg of magnesium. This is almost four times the magnesium recommended in the RDA and five times more than the average American gets. People from the countries using sea salt suffer a higher incidence of hypertension and stroke (probably due to the higher sodium intake) but lower rate of CHD (probably due to their higher magnesium intake). With increasing use of pure sodium chloride in these countries over the past 20 years, it is interesting to note that the incidence of CHD has increased accordingly.

Cardiac arrhythmias and magnesium RDAA variety of cardiac arrhythmias have been associated with magnesium dis-equilibrium, including ventricular tachycardias, fibrillations, and ectopic beats. Coronary spasm is also a major pathogenic feature of hypo-magnesemia. For patients with variant angina, 24-hour magnesium retention after intravenous magnesium loading was 60%, while it was only 36% in control subjects. Substantial evidence has associated magnesium deficiency with sudden cardiac death, a condition that claims 300,000 lives every year.

Deficiency in magnesium, aside from having a negative impact on the energy production pathway required by mitochondria to generate ATP, also reduces the threshold antioxidant capacity of the cardiovascular system and its resistance to free-radical damage. Vitamin E has been found to have strong protective properties against magnesium deficiency-induced myocardial lesions and cardiomyopathy. Magnesium acts as an antioxidant against free radical damage of the mitochondria. It has been called nature’s “calcium channel blocker” because of its ability to prevent coronary artery spasm, arrhythmias, and to reduce blood pressure.

C. Pre-menstrual Syndrome, Diabetes, Depression, and Chronic Fatigue

Women affected by premenstrual syndrome have been found to have reduced magnesium levels. Since magnesium is a cofactor in hundreds of enzymatic reactions, many of which govern cell membrane function, it is easy to see how magnesium can play a fundamental role in multiple organ systems, although there is no conclusive proof that links low magnesium levels directly to PMS.

Magnesium plays the role of a second messenger for insulin action.Insulin itself has been shown to be an important regulatory factor for intracellular magnesium accumulation. Dietary magnesium supplements have been shown to improve both insulin response and insulin action in non-insulin dependent diabetics.

Getting the Magnesium RDA also helps regulate nerve cell function. Its presence in adequate amounts in the synaptic gap between nerve cells controls the rate of neuron firing. Nerves fire easily when magnesium levels are too low. The effect of this rapid firing is increased sensitivity to stimulation of all kinds. Noise will sound excessively loud, emotional reactions will be exaggerated, and the brain may be too stimulated to sleep. Magnesium deficiency may cause excessive muscle tension (such as spasms, tics, and restlessness) because magnesium is needed at the neuro-muscular junction to allow muscles to relax. Chronic fatigue is another common clinical entity associated with deficiency of magnesium.

A deficiency of magnesium can present common psychiatric symptoms including depression, anxiety, restlessness, and irritability. Depressed patients have been found to have lower levels of magnesium. Oral supplementation of magnesium has been tried as an adjunct treatment in psychiatric patients and been found to be successful in rapidly cycling bipolar affective-disorders.

Magnesium RDA Discussion

Magnesium is perhaps the most under-appreciated mineral in our lives. Over 75% of Americans are deficient, even by the low standards set by the RDA. Physicians and anti-aging researchers alike are now recognizing the growing clinical importance of magnesium.

Magnesium RDA supplementation is recommended for healthy patients as well as for those with osteoporosis, cardiovascular disease, depression, diabetes, chronic fatigue syndrome, premenstrual syndrome, and hypertension.

Blood tests are not a good measure of Magnesium RDA levelsMagnesium deficiency, at the intra-cellular level, is difficult to measure. Blood tests using traditional laboratory methods do not give a good indication of magnesium level from an optimum health and disease prevention perspective. One’s blood test can be “normal” while the intracellular level is “deficient”.

The decision to give magnesium supplementation should therefore rely on evaluation on predisposing factors and symptoms. 100 – 200 mg supplemental magnesium with each meal (three times a day) seems a reasonable and safe recommendation for people with normal kidney function and for those not regularly taking magnesium containing laxatives or antacids. This level of supplementation, coupled with the average dietary magnesium intake, would bring the total daily consumption in line with the 400 – 700 mg a day advocated by many researchers and nutritionally oriented clinicians for optimum health.

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Saito K, et al: Effects of oral magnesium on blood pressure and red cell sodium transport in patients receiving long-term thiazide diuretics for hypertension. Am J Hypertens 1:715-45, 1988.

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© Copyright 2015 Michael Lam, M.D. All Rights Reserved.

Magnesium RDA
5 - "Dear Dr Lam,"
Dear Dr Lam,

L. and I deeply appreciate your presence in our lives. Even though we have not met you (and hope someday we can), we feel a deep sense of connect with you and blessed that life orchestrated our coming in contact with you. It is rare to see such extreme levels of capability, intelligence coexist with such a strong sense of commitment and duty, in the same person, the way they exist in you. Of all the doctors I have ever met in my entire life (and I have met a lot!!), I have felt most touched by your concern and commitment to my well being.

I thank you from the bottom of my heart for being who you are and for bringing hope and wellness back into my life. I feel like you have gifted me a new life by bringing me out of the lowest point in my life where I was on the verge of losing all hope of ever having a normal life. I can never thank you enough for what you have done and for what you continue to do for me.

Thank you so much again Dr Lam. We shall always remain deeply grateful to you. The world needs many more of you!

With love and gratitude,


  • Robert says:

    Hi Dr. Lam. I know this is a bit off-topic, but I was wondering something about Mg. If it can bind calcium, is regular magnesium supplementation an effective strategy to help prevent kidney stones? Thanks!

    • Dr.Lam says:

      It does not because many other pathways are involved and not so simple. When you have too much magnesium, you get diarrhea also.

      Dr Lam

  • Isabella says:

    Is it true that magnesium can also help with constipation?

    • Dr. Lam says:

      Magnesium is an excellent laxative, if you take enough. For most people that can range from 500-2000 mg. It is also nature’s muscle relaxant and excellent sleep aid. It is perhaps one of the most under appreciated nutrient. All of us need more because the soil that provide magnesium for plants have been reused often and not replenished enough.

      Dr Lam