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BP Differentials in Twins Correlated with Sodium Intake

— Twin with higher blood pressure also had higher waist circumference

Last Updated September 15, 2018
MedpageToday

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CHICAGO -- Sodium intake had a bigger-than-expected relationship with blood pressure in a twin study presented here.

Among 88 identical twin pairs enrolled in Milwaukee and East Lansing, Michigan, 37 had blood pressure (BP) that differed by ≥ 10 mm Hg between co-twins (who were both off antihypertensive medications). In these so-called "discordant" pairs, BPs averaged 138/85 mm Hg for one and 121/77 mm Hg for the other, according to Vidyka Kidambi, MD, of Milwaukee's Medical College of Wisconsin, and colleagues.

Action Points

  • Note that this study was published as an abstract and presented at a conference. These data and conclusions should be considered to be preliminary until published in a peer-reviewed journal.

On average, twins with higher BP ate more sodium per the Block Sodium Screener (3,900 versus 3,261 mg/day) and had greater waist circumference (105 cm versus 98 cm), Kidambi showed in a poster at the Joint Hypertension 2018 Scientific Sessions of the American Heart Association and the American Society of Hypertension.

Differences in sodium intake were significant independent of central adiposity, indicating significant sodium sensitivity in discordant twin pairs, the researchers concluded. They highlighted that the effect of about 500 mg less sodium per day suggests that modest decreases in sodium intake among sodium-sensitive individuals may be sufficient to see a reduction in BP. However, the study did not address other dietary factors or other parameters that may correlate with sodium intake and influence blood pressure.

"I'm not surprised that decreased sodium intake was associated with decreased BP," commented Matthew Denker, MD, of the Hospital of University of Pennsylvania. "But I was surprised by the effect size seen -- 17 mm Hg by my quick calculation. This greatly exceeds the typical numbers quoted," he told ľֱ.

The twin study did not actually look at an intervention to lower sodium, pointed out Donald Lloyd-Jones, MD, of Northwestern University in Chicago. He said that the study had an "interesting design," even if it is already known from controlled studies that reducing sodium intake from usual levels will lower BP.

Lloyd-Jones and Denker were not involved in the study.

The twins included in the study were age 44 on average, and 63% were women, while 96% were Caucasian. BP was taken as an average of three measurements.

  • author['full_name']

    Nicole Lou is a reporter for ľֱ, where she covers cardiology news and other developments in medicine.

Disclosures

Kidambi disclosed no relevant relationships with industry.

Primary Source

Hypertension 2018

Kidambi V, et al "Does Dietary Sodium Contribute to the Discordance in Blood Pressures among Monozygotic Twins?" Hypertension 2018; Abstract 090.