Blood Pressure - Calcium and Magnesium

Calcium and magnesium are minerals that are essential for health. Calcium is needed for strong bones and teeth and for muscle function, nerve function, and more.

Therefore, getting sufficient calcium either from foods or food supplements is essential. We require at least 800 milligrams of calcium daily and some health professionals think that we need more.

Women, especially, need as much as 1,500 milligrams daily. Calcium is called a macro-mineral because our bodies require a lot. The minimum daily dosage of 800 milligrams of calcium would weigh about 1.5 grams as calcium carbonate or calcium citrate and would be a large pill.

In contrast, other minerals, except magnesium, are required in amounts so small they would barely cover the dot in the letter i. Dietary surveys indicate that less than 40 percent of us get the 800 milligrams daily from our diet, let alone 1,500 milligrams.

Milk and other dairy products are the major source of calcium. About three glasses of milk daily is equivalent to 800 milligrams of calcium and 1,500 milligrams equals about five glasses.

The sodium content of cheese makes it unacceptable on this plan, so the only alternative is deep green vegetables, such as spinach and broccoli. But 800 milligrams of calcium requires about eight stalks of broccoli or about 25 ounces of spinach, both unlikely amounts to be eaten.

Most dietary surveys indicate that Americans don’t consume nearly enough milk or deep green vegetables to obtain 800 milligrams, let alone the 1,500 milligrams recommended by the government consensus panel.

Since calcium is so essential to good health, calcium supplements make good sense. In many cases, they are the only recourse. Just as the ratio of potassium and sodium is important to each living cell, so is the ratio of calcium outside the cell to calcium inside the cell.

Calcium is required by the cell membrane to maintain its integrity. If the ratio of calcium outside the cell to calcium inside the cell drops, because we either don’t get enough calcium or we excrete too much, the cell membrane loses its integrity.

It becomes “leaky” and allows sodium and more calcium to enter and potassium to leak out. Recent research indicates that excess sodium seems to cause more calcium excretion. When calcium levels inside the muscle cell become too high, the cell tightens up.

Tighter peripheral muscles that line the arterioles means the arterioles and capillaries are more constricted, which increases peripheral resistance to blood flow and blood pressure. The heart has to pump harder to force the blood through the capillaries.

Inadequate calcium can cause the blood pressure to rise. This effect of calcium is indirect, because it’s not primary to high blood pressure, but each seemingly minor effect can add up to a major problem.

Water flows smoothly through a garden hose until you either fold it over to stop the flow completely, fold it a little to slow down the flow, or constrict it with a clamping device. Any one of these actions causes the pressure in the hose between the constriction and the faucet to increase.

You can even see the hose become swollen, and leaks sometimes spring at weak points. The garden hose analogy can help us visualize what happens when peripheral resistance increases. Tiny muscles surrounding the arterioles tighten and constrict them. Constricted arterioles restrict blood flow.

Restricted blood flow, like the constricted garden hose, means higher blood pressure between the heart and the surface. And the leaks in the hose have their counterparts in blood vessels; the only difference is the damaged item is not easily replaced at the hardware store.

Magnesium is another mineral essential to many bodily functions. It is required for muscle contraction and many processes in metabolism. Nutritionists classify it as a macro-mineral because we require 400 milligrams daily. Most of our magnesium comes from milk, meat, and vegetables.

Surveys indicate that only about 50 percent of people get the correct amount of magnesium daily. In my opinion, nutritionists, dietitians, and doctors don’t emphasize the importance of magnesium enough. So the public remains generally uninformed.

Magnesium, like calcium, is necessary for membrane integrity, and integrity of the membrane is essential for maintaining the correct potassium-sodium-calcium ratio. Ultimately, this membrane integrity influences peripheral resistance, because it will cause the muscles to either relax or to remain tense.

Since low blood levels of magnesium have been associated with high blood pressure, a reason other than its membrane effects on the potassium-sodium-calcium system has been sought.

There is some evidence to show that renin is elevated when blood levels of magnesium are reduced, and elevated renin produces elevated blood pressure.

Unfortunately, no one can give the precise amount of dietary calcium necessary to prevent high blood pressure. That is because potassium, sodium, and magnesium are all involved.

Calcium and magnesium work in tandem; magnesium is needed for calcium absorption. As a general guideline, you need about 800 milligrams of calcium and 400 milligrams of magnesium.

If you are a woman before menopause, 1,000 milligrams of calcium is appropriate, and for postmenopausal woman, 1,500 milligrams is better. It makes sense to use a daily calcium supplement to obtain about 400 to 600 milligrams of calcium as calcium citrate.

Ideally, the supplement would also provide about 200 milligrams of magnesium. Many supplements supply this ratio. Some experts, especially health food store proprietors, will say there is a magic ratio of calcium to magnesium, but this is not true.

A great deal of research has shown that if you are deficient in magnesium, it affects calcium absorption up to about 200 to 400 milligrams of magnesium daily, depending on your size and activity level.

Once you have achieved that required level of magnesium, your body will absorb and utilize its calcium whether you get only 400 milligrams or the 1,200 to 1,500 milligrams recommended. Food technologists have been able to fortify orange juice with calcium.

In fact, a glass of calcium-fortified orange juice provides as much or more calcium than a similar glass of milk. But the orange juice goes one better; it is a potassium powerhouse. Orange juice provides plenty of potassium, is low in sodium, and, with the calcium, cannot be outdone by any other beverage.