Just like how water exerts pressure on the walls of the pipes when flowing, blood too exerts pressure on the surface blood vessels.
The pressure exerted must be constant and of a particular value. A drop or hike in this pressure may likely be a warning of an abnormality.
When the pressure exerted by blood on the walls increases beyond a certain level, it is known as hypertension or high blood pressure.
Hypertension is a common health condition. Nearly half the American population is expected to be diagnosed with hypertension.
Symptoms Of Hypertension
Most people don’t experience any particular symptom until the condition becomes severe. That is why hypertension is rightly known as the "silent killer”. Even when people do experience the symptoms, they are almost always associated with other issues.
What Are The Symptoms Of Hypertension?
- Severe headaches
- Nose bleed
- Difficulty in breathing
- Chest pain
- Extreme tiredness and fatigue
- Sweating and anxiety
What Causes Hypertension?
The causes of hypertension or high blood pressure are still being studied. Some of the well-accepted and scientifically proven causes are smoking, obesity or being overweight, diabetes, having a sedentary lifestyle (one involving very minimal physical activities), and unhealthy eating habits.
When it comes to diet, a high salt intake can result in hypertension, especially if you are 'salt-sensitive.'
What Is Salt Sensitivity?
We all require some amount of salt in our diets to survive. As its chemical name sodium chloride suggests, salt contains an important mineral, sodium.
Salt sensitivity is a measure of how your blood pressure responds to salt intake. People are either salt-resistant - their blood pressure doesn't change much with salt intake or salt-sensitive - their blood pressure increases upon salt consumption.
About 60% of people with high blood pressure are thought to be salt-sensitive.
How to determine if you are salt sensitive?
If you suspect salt sensitivity, the best way forward is to approach your medical practitioner.
Your practitioner may initially put you on a low sodium diet. This can then be switched to a high sodium diet.
If there's a rise in the blood pressure by 5-10% after the switch, then you may be considered salt sensitive.
The Story Behind Salt Sensitivity
When our ancestors were roaming about in Africa, many thousands of years ago, salt may have been a scarce nutrient in their diets.
Our bodies require salt for a lot of important functions like muscle contraction, maintaining blood volume, and sending messages and signals between the cells.
Salt also plays a role in water retention in the body. In archaic times when our ancestors were out and about in the Savannah, exposed to the sun for long periods of time, being salt-sensitive would have given them an advantage by losing less water to the environment.
Salt retention became even more essential when infectious diseases (which often cause people to lose sodium through diarrhea and vomiting) started to spread.
Researchers speculate that this is the reason why humans probably developed the sensitivity to salt.
So, an ability to hold on to this nutrient was a survival advantage in many ways.
Unfortunately for many of us, we have retained this evolutionary ability to hold on to calories and sodium ever so dearly. Being surrounded by an environment filled with high-salt and high-calorie foods has automatically ended up increasing our risk of obesity and hypertension.
Surprisingly, salt is not only found in salty foods, but many sweet-tasting foods have large amounts of salt in them. Salt is used as a taste enhancer and a preservative.
Many brands that make cake and pastries hide some amount of salt in them in order to enhance the taste.
ACE Gene, Salt (Sodium), And Blood Pressure Control - Molecular aspect
The kidneys control blood pressure by either excreting or reabsorbing sodium. Since sodium moves with water, it is excreted as urine when the blood pressure needs to be lowered. By contrast, the kidneys reabsorb sodium in order to increase the blood pressure.
Our blood pressure is also regulated by the widening and narrowing of the blood vessels to regulate the blood flow.
Whenever there's a drop in the blood pressure, it triggers the release of a hormone, renin, from the kidneys. Renin helps form a molecule, angiotensin 1. Angiotensin 1 and 2 are two forms of the hormone angiotensin, that controls the narrowing of the blood vessels to regulate blood pressure. Angiotensin-converting enzyme or ACE, released by the lungs, converts angiotensin 1 to angiotensin 2. Angiotensin 2 triggers the release of another hormone, aldosterone, that helps kidneys reabsorb sodium and water, thereby increasing the blood pressure.
The genetics behind salt sensitivity and blood pressure
Some types of ACE gene increase the production of the angiotensin-converting enzyme. This results in an increased sodium absorption, thereby causing a higher than normal spike in the blood pressure.
rs4343The SNP rs4343 influences the production of the angiotensin-converting enzyme in response to sodium (salt) in blood. The G allele of rs4343 has been associated with the increased production of the enzyme, and thus an increased risk for high blood pressure. 38% of the population is known to have this allele, and these people are likely to be salt-sensitive.
Food recommendations for salt-sensitivity
People who are salt sensitive should watch the sodium content in their diet. Foods that are low in sodium and high in potassium are recommended - potassium lessens the effect of sodium.
The DASH diet is popular among people with high blood pressure. This diet emphasizes fruits and vegetables - both of which are low in sodium and high in potassium. It also includes nuts, whole grains, poultry, and fish.
Dairy products also are a good addition to the diet. Milk, yogurt, cheese, and other dairy products are major sources of calcium, vitamin D, and protein.
Other low sodium foods include basil, apples, cinnamon, brown rice, kidney beans, and pecans.
While retaining salt in the body was a survival advantage for our ancestors, the same has become a villain in this day and age of high-calorie and high-salt foods all around. Hypertension, characterized by a persistent elevation in the blood pressure, is a risk factor for many serious conditions like heart disease and stroke. Depending on our sensitivity to the sodium in salt, our blood pressure either spikes or lurks in the normal range upon consumption of salt. The ACE gene plays an important role in determining our sensitivity to salt. The ‘salt-sensitive’ individuals must be wary of the amount of sodium (salt) intake in order to maintain their blood pressure in the normal range. The DASH diet is popular among people who are trying to limit their salt intake.