- Hypertension, or high blood pressure, affects an estimated 1.28 billion adults worldwide, many in low and middle-income countries.
- If blood pressure is not controlled, it can increase the risk of heart, brain, and kidney diseases.
- One common but less known cause of hypertension is salt sensitivity — where the body fails to excrete excess salt.
- A new review has found that women of all ages are more salt sensitive than men, which may have implications for blood pressure control.
According to the
There are several well-known factors that increase the risk of hypertension. These include:
- Age: Hypertension is more common over the age of 65
- Ethnicity:
Some ethnic groups are more prone to hypertension than others - Weight:
Obesity is a primary risk factor for hypertension - Regular
alcohol and tobacco use - Sex: males have a higher risk of developing hypertension than females. However, this is only until females reach menopause
- Existing health conditions: Cardiovascular disease, diabetes,
chronic kidney disease , and high cholesterol levels can lead to hypertension, especially as people age
A less recognized factor that can drive up blood pressure is salt sensitivity — the tendency of the body to hold onto salt rather than excrete it through the kidneys.
A review of epidemiological data published in
“The most important fact highlighted in this review article is that women, whether pre or postmenopausal, are more salt sensitive than men.”
— Dr. Eric Belin de Chantemèle, study author and physiologist at the Vascular Biology Center at the Medical College of Georgia at Augusta University.
Salt comprises around 40% sodium ions and 60% chloride ions. We need a small amount of sodium, around 500mg (or a quarter teaspoon of salt) per day, to conduct nerve impulses, contract and relax muscles, and maintain the proper balance of water and minerals.
However, most people take in more sodium than they need. In higher-income countries, some 75% of salt intake comes from processed foods and meals eaten outside the home.
The
According to the CDC, research shows a strong relationship between the amount of salt consumed and
Globally, people consume an average of 9 to 12 grams of salt daily — around double the
Some people can
The
And this review suggests that salt sensitivity is a factor in about half of the cases where the cause of hypertension is not apparent and that it also often contributes to
It has long been recognized that
This review, however, suggests that because females are predisposed to salt sensitivity, which may raise BP, the reality is not as straightforward as that.
The explanation they suggest is, perhaps, surprising. According to Dr. Belin de Chantemèle, human and laboratory animal evidence indicates that female kidneys are better at excreting salt. The problem, it appears, is with the vasculatue, because salt should also relax the blood vessels, but it does not in those who are salt-sensitive.
“Although sex steroid hormones are important in the regulation of the cardiovascular system, new research suggests that sex chromosomes may also be involved. […] Increased vascular resistance from salt sensitivity leads to endothelial dysfunction, which may be more of a factor in females than in males.”
— Sebnem Unluisler, M.Sc., genetic engineer at the London Regenerative Institute.
When the blood vessels relax and expand, BP reduces. However, if the blood vessels do not relax, BP increases.
Dr. Belin de Chantemèle said that the blood vessels do not relax in many women, making them prone to salt-sensitive BP changes.
The role of
Dr. Meagan Williams, internist and Director of Women’s Health at Harbor Health, told Medical News Today why this might happen:
“SSBP [salt-sensitive blood pressure] increases after menopause — which could suggest that female sex hormones (like estradiol) are actually protective against SSBP, rather than the factor that makes women more salt sensitive.”
But it may not be just estrogen that is having an effect. Dr. Belin de Chantemèle highlighted the role of another hormone in SSBP:
“Data from our own studies and the literature point towards an inability of women to decrease the production of the salt-retaining hormone aldosterone which also controls the ability of blood vessels to relax. Improper levels of aldosterone in response to salt ingestion appears to reduce the ability of blood vessels to relax.“
“I think it’s hard to make recommendations for salt-sensitive women based solely on this review article, since it is primarily showing us that women are more salt sensitive than men and postulating as to why that is, [not] necessarily what to do about it. However, in general, it’s good for women who are salt sensitive to be attentive to their dietary sodium intake and try to reduce it if possible.”
— Dr. Meagan Williams
And this advice is valid for everyone, not just salt-sensitive women, as Dr. Belin de Chantemèle explained:
“People need to follow the recommendations of the American Heart Association regarding salt consumption. Currently, the average amount [of sodium] consumed per day is 3.4g when the AHA recommend 2.3g knowing that the ideal amount would be 1.5g.”