Sodium Sensitivity

Sodium Sensitivity

The main source of sodium is salt. 85% of the salt in our diet come from processed foods and 15% from added table salt during cooking. High levels of sodium intake can lead to high blood pressure and therefore increased risk of hypertension. However, the effect of a high sodium intake on blood pressure (also known as sodium sensitivity) varies considerably between individuals. Someone with sodium sensitivity experiences a large increase in blood pressure in response to a change in sodium intake.

What is the ACE gene?

The ACE gene produces an enzyme that converts the inactive Angiotensin I to the active Angiotensin II. Angiotensin II results in a narrowing of blood vessels which increases blood pressure. Angiotensin II also stimulates production of the hormone aldosterone, which triggers the absorption of sodium and water by the kidneys, leading to an increased volume of fluid in the body and higher blood pressure.

What is the effect of genetic variation at the ACE gene?

A number of factors determine a person’s risk of hypertension, including diet, lifestyle and genetics. Genetic factors contribute to an individual's risk of blood pressure. The genes ACE and SLC4A5 are particularly key determinants.

For example, individuals with an allele at the ACE gene produce more ACE enzyme, which results in a more active RAS system. A more active RAS system results in a heightened sensitivity to sodium intake and a higher risk for hypertension with high sodium intake. In this way, genetic variation at the ACE gene can lead to high blood pressure.

Do note that there is an important ethnic variation in the effect of ACE on blood pressure. More specifically, ACE alleles are related to high blood pressure in white ethnicities but not in black or Asian ethnicities.

Why is the SLC4A5 gene important?

The SLC4A5 gene codes for a sodium bicarbonate transporter which is involved in sodium transport. When risk alleles are present, the function of the transporter is impaired, which reduces the reabsorption of sodium. This results in reabsorption of sodium via other transporters at the expense of an increased sodium intake. This increases blood pressure and the risk of the hypertension.  

What is hypertension?

Hypertension refers to elevated blood pressure levels exceeding 140/90 mmHg (according to WHO criteria). Hypertension is one of the most important risk factors for cardiovascular diseases, such as stroke, myocardial infraction and renal disease. It affects almost a quarter of the adult population in Western societies.

Who is most at risk of hypertension?

The allele at the gene ACE influences sodium sensitivity and therefore risk of hypertension. The prevalence of sodium sensitivity was much higher in individuals with two alleles and one allele (over 50%) compared to individuals with no SNP.

If addition to the presence of risk alleles, individuals with a medical risk such as diabetes, obesity or kidney disease, are at higher risk of hypertension when consuming a sodium-rich diet.  

Why should I increase my potassium intake?

Sodium is absorbed in the small intestine by sodium-potassium channels that go through the cell membrane. When a channel absorbs sodium into the small intestine, potassium is transported in the opposite direction, out of the small intestine. A potassium-rich diet leads to the net movement of sodium out of the small intestine, rather than into it. This high sodium excretion leads to lower blood pressure and reduced risk of hypertension.

Backed by Science

Our in-house scientists have sorted through thousands of studies and we only use genes that are backed by a significant body of peer-reviewed research. Check out Nell’s Science Standard for more information.