Selenium Can Lift the Spirits
Ask a group of men to report on their moods throughout a study and, more
often than not, their answers will not change significantly.
"Gender seems to be a factor in self-reported mood changes," says
psychologist James G. Penland, who is at ARS' Grand Forks Human Nutrition
Research Center in North Dakota. Whether women are more aware of subtle
changesor men are more resistant to disclosing how they feelhe
says, "men are less likely to report differences" . . . except in
recent studies of selenium.
Well-known for its antioxidant prowess, this essential trace element now
appears to lift the spirits, according to findings at the Grand Forks center
and the Western Human Nutrition Research Center in San Francisco. The ARS
studies support a 1990 report from scientists in Wales that extra selenium
improves mood, says Penland.
Each week during the 15-week study at Grand Forks, Penland had 30 male
volunteers fill out the standard Profile of Mood StatesBipolar Form. It
measures where the respondent falls between two extremes for six types of mood,
such as clearheaded versus confused or elated versus depressed.
By the end of the study, the 15 men who consumed the selenium-rich diet
reported feeling significantly more clearheaded and elated than they did at the
beginning of the study. Changes among those getting the selenium-poor diet were
On average, the men on the selenium-rich diet reported slight improvements
in all six mood extremes as the study progressed, while the men on the
selenium-poor diet felt worse.
The selenium-rich diet contained about 240 micrograms (mcg)that's
millionths of a gramwhich is 3.5 times the Recommended Dietary Allowance.
The selenium-poor diet contained only about 28 mcgor 40 percent of the
Mood differences also showed up among the men who consumed the selenium-poor
diet, says Penland, because some started with higher body stores of the mineral
than others. Every 3 weeks, the volunteers gave blood samples so researchers
could analyze the red blood cells for selenium levels and check the activity
levels of a selenium-dependent enzyme. These measurements indicate how much
selenium is available in the body.
The men whose enzymes were more active scored significantly higher in all
six mood states. They felt more agreeable than hostile, more clearheaded than
confused, more composed than anxious, more confident than unsure, more elated
than depressed, and more energetic than tired. That's even though enzyme
activity for all men in the low-selenium diet group was within the
"normal" range, says Penland.
At the Western center, researchers got similar results when 11 men reported
their moods during a 4-month study. Among the group on the low-selenium diet,
those with the higher selenium levels in their red blood cells felt
significantly more elated and agreeable.
Dietician Lori Matthys says that the selenium content of all foods used in
the Grand Forks study was so variable that each lot of meat, dairy, flour,
cereal, fruit, and vegetables had to be chemically analyzed to ensure that the
volunteers got their assigned intakes.
Selenium is highest in high-protein foods. Fish, shellfish, meat, poultry,
eggs, breads, many cereals, sunflower seeds, and cashews are good
sourcescontaining between 10 and 80 micrograms per 3.5 ounces. Beef and
pork kidney contain more.
A few Brazil nuts can provide more selenium than the amounts used in either
study. One ounce of the nuts contains between 300 and 850 micrograms. But
selenium can be quite toxic, so use with caution. The World Health Organization
suggests a daily limit of 400 mcg. By Judy McBride, ARS.
Penland is at the USDA ARS
Forks Human Nutrition Research Center, P.O. Box 9034, University Station,
Grand Forks, ND 58201; phone (701) 795-8471.
"Selenium Can Lift the Spirits" was published
in the October 1995
issue of Agricultural Research magazine.