10 Questions with Susan Carlson
We talked to Susan Carlson about her research studying the health benefits of docosahexaenoic acid (DHA).
Can you tell us a little about yourself... where you grew up?
I grew up on a farm in the Cascade Mountains of Washington State and attended Washington State University where I studied food and nutrition. I met my husband Gerry when we were both 17, and we married after our junior year. We entered the Peace Corps in Brazil soon after, but that was cut short when I became pregnant with our son.
When did you first realize that you were interested in studying nutrition?
My interest in studying nutrition began after high school graduation where I worked at the USDA Fish Nutrition Laboratory near my home. It was solidified when I got to Iowa State University, where I was given a choice between an assistantship in foods and one working on lipid nutrition. I chose the latter.
During your time here, you have received international attention for your research into DHA. What is it about DHA that is so beneficial to humans — and to pregnant women and infants in particular?
DHA is what we call a “conditionally” essential nutrient meaning there is a biochemical pathway to convert it from a fatty acid found in most vegetable oils, but that conversion is not sufficient to result in sufficient DHA for optimal health. It is now clear that pregnancy and infancy are times in life when DHA is conditionally essential. We know that because studies that provide additional DHA during both pregnancy and infancy have shown a variety of benefits. The most studied outcomes are preterm birth and infant visual acuity and cognitive development.
Early on in your career, you took an interest in pediatric nutrition and — in particular — how breastfeeding is beneficial to infants. Why were you drawn to this specific area of nutrition?
When I was at the University of Southern Florida, I had the chance to do my first clinical study in infants. We were comparing linoleic acid levels in two infant formulas. We found that both formulas had about half as much DHA and ARA as in breast-fed infants. When I learned that these two fatty acids account for up to 50% of fatty acids in brain neurons and that there were visual deficits in nonhuman primates fed diets that reduced brain DHA, I became very interested in infant nutrition.
What brought you to KU Medical Center?
My husband took a job as the Marion Merrill Dow Professorship and Chair of Molecular Biology and Biochemistry at the University of Missouri-Kansas City, so we moved to Kansas City and I took a job as a professor of nursing there. Two years later I learned of an opening at KU Medical Center in the Department of Dietetics and Nutrition. I applied for the job and got it.
Your latest study is on how DHA can affect the incidence of early preterm births. Can you tell us what your research found?
We found a lower probability of early preterm birth (less than 34 weeks) and preterm birth (less than 37 weeks) in women assigned to a higher dose of DHA (1000 mg) than the amount of DHA in many prenatal supplements (200 mg). Women with high DHA status at baseline had a very low rate of early preterm birth regardless of assigned dose (1.3%). We also found fewer serious adverse events with the higher dose in both participants and their infants.
Are you recommending pregnant women try to get their DHA through nutrition... or are supplements being recommended?
As a nutritionist, I always say diet first. However, it would be very difficult for women to consume 1,000 mg of DHA every day from food alone, so a supplement would be needed for women with low DHA status.
How do you get the word out to obstetricians and physicians about the importance of DHA for pregnant women?
There were four obstetricians involved in our study, and they are using their contacts to help get the word out. The study has also been picked up many a number of outlets that reach obstetricians. What is lacking is a way for obstetricians and clinicians who care for pregnant women to easily know which women have with low DHA status. We are working to develop a pragmatic way for obstetricians and other clinicians who care for pregnant women to identify women using DHA intake instead.
What are you working on now? Do you have any potentially exciting research projects in the works?
We have a quality improvement project with Dr. Gene Lee in KU Medical Center’s Department of Obstetrics and Gynecology to identify women with low DHA intake at their first prenatal visit. We know that women in our DHA study who consumed less than 150 mg DHA per day at baseline benefited from the higher dose with less early preterm birth.
What do you enjoy doing in your spare time?
I spend a lot of my spare time gardening. My husband and I grow vegetables and fruit on a large lot that I purchased in 2007. I also have a large garden at our home that I’ve been working on for almost 25 years. I’m still a farm girl at heart!