MADRID — Melatonin supplementation can improve nocturnal blood pressure control and prevent early morning pressure surges in hypertensive patients who do not show the typical nighttime pressure drop, according to results presented at the annual meeting of the European Society of Hypertension.
But another dietary supplement—vitamin E—was shown to increase blood pressure in diabetic hypertensive patients in a second study reported at the meeting.
“Impaired nocturnal blood pressure fall is associated with increased risk of target organ damage related to hypertension,” said Dr. Yehonatan Sharabi of the Chaim Sheba Medical Center, Tel Hashomer, Israel, presenting the melatonin study.
It is not clear why some patients fail to show the usual nighttime pressure drop, but lack of melatonin, a hormone secreted by the pineal gland, may play a role. In patients with a blunted nocturnal blood pressure fall, the amount of urinary 6-sulfatoxymelatonin, the key metabolite of melatonin, is markedly reduced.
The Israeli team, with researchers at Gazi University, Ankara, Turkey, tested melatonin in 38 nonobese hypertensive patients already on one or more antihypertensive drugs. They were generally well controlled except for the impaired nighttime pressure fall and increased early morning pressure surges. Mean age was 64 years, with a range of 42–83 years. Those with insomnia were excluded.
After a 2-week placebo run-in period, the patients underwent baseline 24-hour ambulatory pressure monitoring, then were randomized to either 2 mg of controlled-release melatonin per day or placebo. They were instructed to take the assigned tablet 2 hours before bedtime. After 4 weeks, they underwent 24-hour monitoring. At baseline, the melatonin patients had mean morning pressures of 141/78 mm Hg and mean nighttime pressures of 136/72 mm Hg. The placebo group showed similar baseline values. There were no significant changes in daytime systolic pressure in response to melatonin. But nighttime pressures showed a mean drop of 7 mm Hg systolic and 3 mm Hg diastolic in the melatonin group. There was no such change in the placebo group.
“The time interval from 1 a.m. to 5 a.m. seemed to be the period of maximal melatonin effect on blood pressure, and this is very important, given the incidence of early morning cardiovascular events,” said Dr. Sharabi. No adverse effects were associated with melatonin, and compliance was high, he said.
In a separate study, vitamin E induced substantial increases in mean daytime and nighttime blood pressures in diabetic patients with hypertension, compared with those who were given a soy oil placebo, reported Dr. Ian B. Puddey of the department of medicine, University of Western Australia, Perth.
Although the supplements reduced oxidative stress, as indicated by consistent falls in urinary isoprostane (a marker of oxidative stress), this presumable benefit is nullified by the unexpected rise in systolic and diastolic pressures, as well as pulse pressure and pulse rate.
After a 3-week run-in period, 55 patients with type 2 diabetes and hypertension were randomized to placebo (soy oil stripped of all tocopherols), 500 mg/day of alpha-tocopherol, or 500 mg/day of mixed gamma-, alpha-, and delta-tocopherols. About half of the patients were on at least one antihypertensive drug; two-thirds were on lipid-lowering drugs.
“Contrary to our central hypothesis, we observed a small fall in blood pressure in the placebo group but increased mean pressures in both the alpha-tocopherol and mixed tocopherol groups,” said Dr. Puddey, who presented the data on behalf of the lead investigator, Dr. N.C. Ward. The mean increase was 7 mm Hg systolic and 5 mm Hg diastolic for the patients treated with vitamin E. The 24-hour ambulatory profile showed a sustained and consistent pressure increase throughout the day, with no diurnal variation.