Consuming sodium may increase dizziness, not alleviate it, study finds

11 Feb 2019 --- Contrary to popular belief, a higher intake of sodium can increase lightheadedness instead of alleviating it. This is according to a new study from the Beth Israel Deaconess Medical Center (BIDMC), which examined the link between sodium intake and lightheadedness as part of the DASH-Sodium trial (Dietary Approaches to Stop Hypertension). Published in the Journal of Clinical Hypertension, the results challenge traditional ways of tackling low blood pressure-related dizziness.

“Our results serve to caution health practitioners against recommending increased sodium intake as a universal treatment for lightheadedness. Our results also demonstrate the need for additional research to understand the role of sodium, and more broadly of diet, on lightheadedness,” says Dr. Stephen Juraschek, the study's corresponding author and a Primary Care Physician at BIDMC.

The DASH diet is a lifelong approach to healthy eating that is designed to help treat or prevent high blood pressure (hypertension). The diet encourages individuals to reduce the sodium in their diet and eat a variety of foods rich in nutrients that help lower blood pressure, such as potassium, calcium and magnesium.

The researchers used data from a preexisting DASH-sodium trial, a randomized crossover study that looked at the effects of three different sodium levels (1500, 2300, and 3300 mg/d) on blood pressure.

Participants consumed each of the three sodium levels in random order for four weeks. Half of the participants ate the sodium levels in the context of a typical American diet (a control diet), while the other half ate the sodium levels consistent with DASH diet guidelines. The original trial showed that by lowering sodium intake, blood pressure was also lowered, which became the basis for current guidelines on sodium consumption. 

Additionally, the study asked participants to rate their experience of lightheadedness when they stood up, but these results were not reported. Subsequently, in this new, secondary analysis of the DASH-sodium trial, the researchers looked into the effect of higher sodium intake on postural lightheadedness. 

According to the study results, preconceptions that reduced sodium intake can cause lightheadedness may not be scientifically accurate. The study also addresses sodium’s impact on cardiovascular health.

“Health practitioners initiating sodium interventions for orthostatic symptoms now have some evidence that sodium might actually worsen symptoms,” notes Dr. Juraschek. 

“Clinicians should check on symptoms after initiation and even question the utility of this approach,” he adds. More importantly, further research is needed to understand the effects of sodium on physical function, particularly in older adults.

The study also examined subgroups of the population, including adults over the age of 60 and obese adults. The effects of sodium on lightheadedness were different among these two groups. Essentially, higher sodium increased lightheadedness in younger people but modestly reduced lightheadedness in older adults.

“Sodium is widespread in our food, yet its effects are poorly understood,” says Dr. Juraschek. “This study illustrates the importance of more trials involving the foods we eat so that we can better understand what constitutes a healthy diet,” he concludes.

Last year, US News and World Report ranked the National Institutes of Health-developed DASH Diet “best overall” diet among nearly 40 it reviewed. The announcement came just as new research suggests that combining DASH (Dietary Approaches to Stop Hypertension), with a low-sodium diet has the potential to lower blood pressure as well as or better than many anti-hypertension medications.

Previous research has linked high sodium diets to dementia, while a recent study found that following a low salt diet is more effective in lowering blood pressure in women than in men.

Yet in summer 2018, a study showed that for the vast majority of communities, sodium consumption is not associated with an increase in health risks except for those whose average consumption exceeds 5g/day (equivalent to 12.5g of salt, or 2.5 teaspoons). Communities with high average levels of sodium intake (above 5g/day) were mostly seen in China, with only about 15 percent of communities outside of China exceeding this level of consumption.