Magnesium And Hypertension
- So far we’ve explored what causes differences in blood pressure, the importance of diet, the impact of exercise and the cost of stress.Let’s now explore how magnesium can impact blood pressure.According to some studies, magnesium intake of 500 mg/d to 1000 mg/d may reduce blood pressure (BP) as much as 5.6/2.8 mm Hg.Again, when taken in combination with other diet and lifestyle interventions, you should see a marked improvement if you suffer from hypertension.
What Is Magnesium
Magnesium is classed as an essential micro-nutrient.
Micro-nutrients differ from macro-nutrients in that they are needed in smaller quantities but perform essential roles for normal growth and maintenance of health.
There are approximately 18 different minerals classed as micro-nutrients.
Magnesium is able to directly relax the vascular smooth muscle cells and also works with other minerals such as sodium, potassium and calcium to regulate blood pressure.
This makes it unique in its ability to directly and indirectly impact blood pressure.
On a cellular level, hypertension is the result of high sodium compared to low potassium levels.
This is directly attributed to a high sodium / low potassium / low magnesium diet.
Natural Sources of Magnesium
Magnesium is widely distributed throughout plant and animal based foods.
Most green vegetables, legumes, peas, beans and nuts contain high amounts of magnesium.
Unrefined cereals may also contribute to magnesium intake however, refined and processed foods contribute little.
The highest content of food sources of magnesium (in mg per 100g) are:
- Kelp 760 mg per 100 g
- Wheat bran 490 mg per 100 g
- Wheat germ 336 mg per 100 g
- Almonds 270 mg per 100 g
- Cashews 267 mg per 100 g
The body is uniquely capable of regulating magnesium intake from the diet.
One study showed that a diet that was high in magnesium only absorbed 25%, however on a low magnesium diet, there was an absorption rate of 75%.
(Schwartz et al 1984). If you are going to look at magnesium supplementation, please note that it is best absorbed in small quantities throughout the day.
For this reason, powdered forms of magnesium are preferred.
Magnesium is absorbed in the lower small intestine and the colon via passive transport – this means the body does not expend any energy to uptake the mineral.
Like sodium, the kidneys help to regulate magnesium concentrations by excreting it in response to high plasma levels.
The presence of lactose and carbohydrates appears to increase magnesium absorption whilst alcohol and caffeine may cause an increase in urinary excretion.
Remember what we said about a chronically stressed lifestyle that was fueled by caffeine and sugar?
It also prevents magnesium absorption – one of the key minerals needed to regulate rest and relaxation.
Excess magnesium may result in symptoms of diarrhea (more than 600mg), drowsiness, lethargy and weakness.
In the elderly, hypermagnesemia may occur due to the large amounts of antacids and laxatives that may be used.
Forms of Magnesium
If you’re going to look at magnesium supplementation, it is crucial to understand that not all magnesiums are created equal.
- Magnesium Amino Acid Chelate
The best chelated amino acid form of magnesium is aspartate or arginate. The body will therefore absorb the magnesium as if it were a protein structure.
- Magnesium Oxide
Also referred to as “Magnesia”, magnesium oxide is most often used to treat constipation and acid reflux. Not easily absorbed, it has poor levels of bioavailability (only 4%).
- Magnesium Citrate
One of the more popular forms of supplementation, magnesium citrate is derived from the magnesium salt of citric acid, this form of magnesium has lower concentration, but a high level of bioavailability (90%). Magnesium citrate is commonly used as to induce a bowel movement, but has also been studied for kidney stone prevention.
- Magnesium Orotate
One of the most effective form of magnesium supplements. Extensive research by Dr. Hans A. Nieper, M.D. demonstrated that orotates can penetrate cell membranes. This resulted in the magnesium being delivered to the cellular organelles making it particularly effective for those with heart conditions.
- Magnesium Chloride
Often used for industrial use, it is still used as a form of supplementation as it has higher levels of bioavailability when compared to magnesium oxide. Used to manufacture paper, some types of cements and fireproofing agents.
- Magnesium Lactate
This type of magnesium shows moderate concentrations, but higher levels of bioavailability as compared to magnesium oxide. Magnesium lactate is a mineral supplement that is most commonly used for treating digestive issues. Magnesium lactate should be avoided by those with kidney disease or kidney-related problems.
- Magnesium Sulfate
An inorganic form of magnesium commonly referred to as Epsom Salt and is particularly effective for topical application such as soaking in hot baths to relieve muscle cramps.
- Magnesium Carbonate
This form of magnesium has 30% bioavailability rates. Magnesium carbonate has a strong laxative-effect when taken in high amounts. It is also commonly known as chalk, and is used as a drying agent by pitchers, gymnasts, rock climbers and weight lifters.
- Magnesium Glycinate, Malate & Taurates
The best form of magnesium supplement available is magnesium biglycinate as it is easily absorbed and does not appear to cause irritation to the gastrointestinal tract.
Magnesium and Drug Interactions
Nothing, but nothing causes health practitioners more stress than not having the full story.
If you are on medications or supplements, it is CRUCIAL that you are honest and up front about it as sometimes, there are side effects.
Given that magnesium has the ability to lower blood pressure, try to have it away from your normal blood pressure medications.
Some medications that may interfere with magnesium include:
- Antacids – antacids reduce the laxative effects of magnesium
- Antibiotics – some antibiotics known as aminoglycosides affect the muscles, in particular taking
- Anti-coagulants – magnesium may slow blood clotting and can exacerbate medications, leading to increased bruising.
- Bisphosphates – magnesium can decrease how much bishosphate the body absorbs – take 2 hours away before magnesium
- Calcium Channel Blockers – these drugs stop calcium from entering cells, magnesium works in a similar way, taking both may cause blood pressure to go too low
- Digoxin and Gabapentin – digoxin helps the heart beat more strongly, magnesium may decrease how much digoxin is absorbed
- Quinolone or tetracycline antibiotics may decrease effectiveness. If in doubt take 2 hours before magnesium or 6 hours after
- Sulfonylureas – some magnesium salts might increase how much sulfonylurea the body absorbs, increasing risk of low blood sugar in some patients
- https://www.nrv.gov.au/glossary#AI accessed on 23rd May 2016
- Liska, D, et al 2004. Clinical Nutrition, a functional approach. 2nd ed. The Institute for Functional Medicine
- Dunne, L.J 2002 Nutritional Almanac. 5th Ed. McGraw Hill