How does Calcium impact Hypertension?

A look at Sodium and Calcium ions. Does calcium provide the same risk as sodium to Hypertension?

Critical elements or minerals in human nutrition are grouped into three main categories on the basis of two factors: amount of the mineral required by the body and its essentiality for human life. Therefore, we look in turn at

1. Major minerals/ions  

2. Essential trace elements, and

3. Probably essential ultra-trace elements (they are being studied to determine their degree of importance for humans).

Elements for which the requirement is greater than 100 mg /day are called major minerals, not because they are more important but just because there are more of them in the body. They make 60% to 80% of all the inorganic material in the human body. Examples are Calcium (Ca), Phosphorus(P), Magnesium (Mg), Sodium (Na), Potassium(K), Chloride (Cl or Cl₂), and Sulphur(S).

Trace elements are needed or available in the body in smaller amount (less than 100 mg/day). Examples are Iron (Fe), Iodine (I), Zinc (Zn), Copper (Cu), Manganese (Mn), Chromium (Cr), Cobalt (Co), Selenium (Se), Molybdenum (Mo), and Fluoride (F).

Essential ultra-trace elements are Silicon (Si), Vanadium (V), Nickel (Ni), Tin (Sn), Cadmium (Cd), Arsenic (As), Aluminum (Al), and Boron (B).

Calcium

Calcium, compared to all the minerals in the human body is present in the largest amounts, constituting 1.5% to 2 % of the total body weight. Most of the body's calcium (99%) is in the bones and teeth. The bulk of the skeletal calcium is deposited as hydroxyapatite [Ca₁₀(PO₄)₆(OH₂)].

Sodium

It follows Calcium as another mineral available in large amounts in the body. Approximately, 120 mg or so in the body of an adult, about one third is present in the skeleton as inorganic, bound material. The remaining two thirds is in the extracellular fluids, largely distributed in plasma and in nerve and muscle tissue. 

Recommended Daily Intake of Calcium:

The recommended daily intake of calcium can vary by age, gender, and other factors. The general guidelines from the National Institutes of Health (NIH) for adults are as follows:

Adults 19-50 years: 1000 mg per day

Men 51-70 years: 1000 mg per day

Women 51-70 years: 1200 mg per day

Adults 71 years and older: 1200 mg per day

Recommended Daily Intake of Sodium:

The recommended daily intake for sodium is generally lower than the average intake in many Western diets. According to dietary guidelines, including those from the World Health Organization (WHO) and the American Heart Association (AHA), the recommended daily intake is typically around 2300 mg of sodium per day for adults. However, many health organizations recommend an even lower intake, such as 1500 mg per day, especially for those with certain health conditions or risk factors for hypertension.

Breaking down the requirement to bit size

According to the American Heart Association, a teaspoon of table salt has about 2,300 mg of sodium. so, 2500 mg of salt would be slightly more than a teaspoon. 1000 and 1200 mg will be about half of a teaspoon or less. The amount of sodium and calcium may vary depending on the type and the size of the salt crystals.

 

The sodium-calcium pump

 The sodium-calcium pump, also known as the Na⁺/Ca²⁺ pump or sodium-calcium exchanger, is a crucial ion transport mechanism found in the cell membranes of many cells, including cardiac muscle cells and nerve cells. Its primary function is to regulate the concentrations of sodium (Na+) and calcium (Ca²⁺) ions within the cell.

 

Here's a simplified explanation of how the sodium-calcium pump works:

 

Resting State:

 

The pump is in a resting state with its binding sites exposed to the cell's interior.

Three sodium ions (Na⁺) from the cell interior bind to the pump's cytoplasmic side.

ATP (adenosine triphosphate) is split into ADP (adenosine diphosphate) and inorganic phosphate (Pi), releasing energy.

 

Phosphorylation:
 

The energy released during ATP hydrolysis is used to phosphorylate the pump. This means that a phosphate group is added to the pump, causing a conformational change.

Change in Conformation:

 

The conformational change in the pump causes it to open to the extracellular side, releasing the three sodium ions into the extracellular fluid.

The change in conformation also exposes binding sites for two extracellular calcium ions (Ca²⁺).

Calcium Binding:
 

Two extracellular calcium ions bind to the pump.

 

Dephosphorylation:

The pump undergoes another conformational change, triggered by the binding of calcium ions, leading to the dephosphorylation of the pump.

Release of Calcium

The dephosphorylation causes the pump to revert to its original conformation, but now on the extracellular side.

The two calcium ions are released into the cell's interior.

Resetting to Resting State:

The pump is now back in its initial resting state, ready to transport more ions.

The net result of this process is the active transport of three sodium ions out of the cell and two calcium ions into the cell for each ATP molecule hydrolyzed. This pump helps maintain the low intracellular concentration of sodium ions and the low extracellular concentration of calcium ions, which are crucial for the proper functioning of cells, particularly in processes like muscle contraction and nerve signal transmission.

 

Sodium and calcium, which is a bigger risk factor for hypertension

 

Sodium is generally considered a more significant risk factor for hypertension (high blood pressure) than calcium. High sodium intake is associated with an increase in blood pressure, especially in individuals who are sensitive to the blood pressure-raising effects of sodium. The relationship between sodium intake and blood pressure is well-established in scientific literature.

 

Excessive sodium intake can lead to an increase in blood volume and contribute to the development of hypertension. The mechanism involves the retention of water by the kidneys to maintain a balance with the increased sodium levels. This increased blood volume puts extra strain on the blood vessels and can lead to elevated blood pressure.

 

Calcium, on the other hand, is thought to have a protective effect against hypertension. Adequate calcium intake is associated with lower blood pressure levels. Calcium plays a role in blood vessel function, and it is involved in the regulation of smooth muscle contraction. in this regard, there are differential view of the consequences when calcium is in excess. Some studies suggest that a diet rich in calcium may help lower blood pressure and reduce the risk of hypertension whiles others suggest when calcium is in high quantity, blood vessels contract, thus squeezing on the blood flow and bringing a build-up of pressure against arterial wall.

 

It's important to note that while sodium and calcium play roles in blood pressure regulation, other factors such as genetics, overall diet, physical activity, and other lifestyle factors also contribute to the development of hypertension. A balanced and healthy diet that includes an appropriate intake of both sodium and calcium is essential for overall cardiovascular health.

It's advisable to consult with a healthcare professional or a registered dietitian for personalized advice on dietary choices, especially if you have concerns about blood pressure or cardiovascular health. They can provide guidance based on your individual health status and risk factors.