The link between serum selenium levels and hypertension is complex and not yet fully understood, with research showing inconsistent results.
Serum selenium levels refer to the concentration of selenium in the blood. Selenium is an essential trace element involved in defense against oxidative stress and may have anticarcinogenic effects not related to its antioxidant properties.
The mean serum selenium concentration in U.S. adults aged 40 years or older is 13.67 mcg/dL.
Selenium intakes and serum concentrations in the United States and Canada vary somewhat by region, with higher concentrations in residents of the Midwestern and Western United States than in the South.
Serum selenium levels are generally measured using atomic absorption or inductively coupled plasma mass spectrometry (ICP-MS).
In the United States, the median serum selenium level among participants in the Third Nutrition and Health Examination Survey was 95 ng/mL, with 99% of participants having levels greater than 95 ng/mL.
At serum selenium levels of less than 130 ng/mL, increases in serum selenium levels were associated with a reduced risk of all-cause and cancer mortality.
However, higher serum selenium levels may be associated with increased mortality.
A serum level of 120-160 μg/l of selenium represents the normal range.
In patients with autoimmune thyroiditis, most patients and control persons showed mild to moderate selenium deficiency (80-120 μg/l selenium).
A diagnosis of selenium deficiency is confirmed by measuring concentrations of selenium in serum or plasma, with values less than 70 ng/mL or 0.8 μmol/L suggesting selenium deficiency
Here’s a summary of the current study understanding:
- A cross-sectional analysis of 2638 adults aged 40 years and older found that high serum selenium concentrations were associated with a higher prevalence of hypertension.
- The multivariable adjusted differences in blood pressure levels and the prevalence of hypertension increased with increasing selenium levels.
- The corresponding odds ratio for hypertension was 1.73 (1.18 to 2.53).
- In spline regression models, a nonlinear association was observed between serum selenium levels and the prevalence of hypertension.
- These findings suggest a potential association between high serum selenium levels and hypertension. However, more research is needed to fully understand the risks and benefits associated with high selenium status in the context of hypertension.
Positive association
- Some studies, particularly among women, have found a positive association between higher serum selenium levels and increased risk of hypertension. This suggests that, within certain ranges, higher selenium levels might contribute to blood pressure elevation.
- For example, a recent analysis of NHANES data found that individuals with the highest quartile of serum selenium had a significantly higher risk of hypertension compared to those in the lower quartiles.
- This positive association might be related to selenium’s potential role in thyroid function and oxidative stress, both of which can play a role in blood pressure regulation.
Negative association:
- Other studies, especially in pregnant women, have shown a negative association between selenium deficiency and preeclampsia, a pregnancy complication characterized by high blood pressure. This suggests that insufficient selenium might contribute to hypertension under certain conditions.
- Lower selenium levels might worsen oxidative stress and inflammatory processes, potentially leading to higher blood pressure.
However, it’s important to remember that correlation doesn’t equal causation. Just because low selenium levels are associated with higher blood pressure doesn’t mean one directly causes the other.
Inconclusive results:
- Some studies, particularly in non-pregnant populations, have found no significant association between serum selenium levels and hypertension. This further adds to the complexity of the relationship.
- Differences in study populations, methodologies, and statistical analyses might contribute to these inconsistencies.
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References
- Martin Laclaustra, Ana Navas-Acien, Saverio Stranges, Jose M Ordovas, Eliseo Guallar. Serum selenium concentrations and hypertension in the US Population. 2009 Jul;2(4):369-76. doi: 10.1161/CIRCOUTCOMES.108.831552
- Ruth M. Ayling & C.D. Thomson. Selenium Blood Level. Clinical biochemistry of nutrition. Sciencedirect.com
