| Summaries of the latest research concerning fish oils and pregnancy and infants |
CONTENTS |
| Maternal Fish Oil Supplementation |
| Infant Development |
| Post-partum Depression |
|
Breast/Formula Feeding
Omega-3 fatty acids and child development Dr. Emily Oken and colleagues at the Harvard Medical School studied over 25,000 children of mothers participating in the Danish National Birth Cohort, a prospective population-based study that enrolled pregnant women between 1997 and 2002. Data was collected on maternal fish intake, the duration of breastfeeding and measures of child development milestones. The primary outcome was total development at 18 months ascertained by an interview. Mothers were questioned about whether the child could climb stairs, remove socks and shoes, drink from a cup, be occupied for 15 minutes with adult participation, fetch an object when requested, write or draw, orient a book correctly, use word-like sounds, and put two words together. Ages at which the child could first sit unsupported and could walk unassisted and the total number of words the child could correctly say was recorded. Data was also collected at 6 months with an appropriate set of questions. From this data scales were constructed and scores derived. Other data collected included birth weight and evidence of early or late delivery (gestational age), maternal smoking and alcohol use and other information which allowed correcting for confounding. It was found that higher maternal fish intake during pregnancy and the duration of breastfeeding were associated with higher child development scores at 18 months. For example, 5.7% of children with a mother in the lowest quintile of fish intake had the lowest total development score at 18 months whereas only 3.5% of children with their mother in the highest quintile of fish intake had the lowest total development score. Women in the lowest quintile consumed < 1 fish serving/week whereas in the highest quintile it was about 3.5 servings/week. Fish most frequently consumed were cod, plaice, salmon, herring and mackerel. Species with high mercury content are not commonly consumed in Denmark. Longer duration of breastfeeding was associated with better development at 18 months. After adjusting for maternal fish intake, longer breast-feeding remained associated with a greater achievement of developmental milestones with a 28% increase when = 10 months was compared with = 1 month. This pattern of association with fish intake and duration of breastfeeding was a robust result which persisted after a number of different corrections for potential confounding.
The authors comment that in the U.S. and Europe, expert panels have advised that pregnant women consume a
minimum of 200 mg/day of DHA. They point out that most women do not consume this much DHA from fish or other
dietary sources, and thus supplements may offer a reasonable alternative. They cite studies which found improved
development in children of women randomly assigned to take supplemental DHA although doses were much higher
(1-2 g/day) than the experts recommended. The authors cite evidence that in the case of the long-chain
polyunsaturated fatty acids, supplementation with a single acid may be less desirable than providing a more natural
balance of these nutrients. Fish oil, for example contains both DHA and EPA.
Fish oil accelerates immune system maturation in infants Healthy maturation of the infant’s immune system would thus involve increased production of gamma-interferon and/or IL-2 and an increase in Th1 cells to improve the ratio of Th1 to Th2 cells. Researchers at Copenhagen University report that supplementation with fish oil at age 9 months helps accelerate maturation. Their study involved 64 healthy Danish infants who were fed either formula or cows’ milk for a 3-month period following cessation of breast-feeding. Half the children were also given a teaspoon (5 mL) of fish oil daily providing 571 mg/day of eicosapentaenoic acid (EPA) and 381 mg/day of docosahexaenoic acid (DHA). The infants had blood samples drawn at the beginning and end of the trial. Analyses of red blood cells showed a 450% increase in EPA and a 40% increase in DHA among infants who had supplemented with fish oil; these increases were accompanied by decreases in linoleic acid and arachidonic acid of 15%.
Whole blood samples were cultured and stimulated with various agents to provoke an immune response. The researchers noted a substantial increase in the production of gamma-interferon and a reduced production of interleukin-10 (IL-10) in the infants supplemented with fish oils. A reduced IL-10 production would indicate a dampened Th2 response to immune system provocation. Fish oil supplementation did not affect other markers of innate immunity or general inflammation (C-reactive protein and immunoglobulin E). The researchers conclude that daily fish oil supplementation between the ages of 9 and 12 months accelerates the maturation of infants’ immune systems and may be helpful in avoiding the development of allergic disorders.
DHA transfer during breast-feeding
Their study involved 12 mother/infant pairs who were enrolled within 30 days of birth. The study participants (both mothers and infants) provided blood samples 1, 2, and 4 months after delivery and mothers also provided samples of breast milk. The researchers found that the DHA content of the mothers’ red blood cells decreased significantly over the 4-month period, while that of the infants increased. It is not clear whether this is due to preferential transfer of DHA, or to differences in the metabolism and utilization of polyunsaturated fatty acids.
DHA declines during breast-feeding Their study involved 57 healthy women (average age of 30 years) who were recruited into the study after 36-37 weeks of pregnancy. The women gave birth after an average 40 week of pregnancy and were than followed for 64 weeks post-partum. Twenty-two of the women exclusively bottle-fed their infants, while the remaining 35 breast-fed. The fatty acid composition of plasma and erythrocytes was analyzed at entry to the study and then at regular intervals post-partum. Dietary intakes of fatty acids were assessed 4 and 32 weeks post-partum via validated food frequency questionnaires.
The researchers found that the total fatty acid content of plasma and erythrocytes decreased significantly post-partum, while the percentages of omega-3 fatty acids increased with the exception of DHA. DHA decreased steadily post-partum in both lactating and non-lactating women, but the decrease was substantially greater in breast-feeding mothers. The average daily intake of DHA at 32 weeks post-partum was 55 mg/day in non-lactating women and 81 mg/day in lactating women. However, it is estimated that the daily transfer of DHA in breast milk is about 51 mg, thus leaving only 30 mg/day for the breast-feeding women, likely not enough to cover their basic needs for this important fatty acid.
Maternal milk and DHA supplementation
Researchers at the Ludwig-Maximilian-Universitat now report that an increased dietary intake of DHA by
a lactating woman results in a proportional increase in her breast milk. Their study involved 10 lactating
women who between week 4 and 6 postpartum supplemented with either 200 mg of DHA per day or 200
mg of a corn/soy oil mixture (placebo oil). At the end of the 2 weeks the DHA content of the milk from the
DHA-supplemented mothers had increased by 28% while the DHA content in the milk from the mothers in
the placebo group had decreased by 25%. In other words, after 2 weeks the DHA content in the milk
from DHA-supplemented mothers was almost twice as high as in the milk from the mothers in the placebo
group. There were no significant differences in the amount of milk produced per day by the 2 groups.
Editor's note: Supplementation with DHA would be particularly important for lactating mothers who are
vegetarian.
Formula-fed infants need DHA The researchers reviewed numerous studies comparing the DHA status of breast-fed infants with that of formula-fed ones. They found that over the first 6 months of life DHA accumulates in the body of breast- fed infants at a rate of 10 mg/day with 48% of this accumulation occurring in the brain. They estimate that an intake of 20 mg/day of DHA is required to achieve this accumulation and point out that breast feeding supplies about 60 mg/day. They believe the seeming over-abundance of DHA in breast milk may be needed in order to provide for potentially increased losses during disease, infection, surgery, and other conditions adversely affecting the infants' metabolism. On the other hand, formula-fed infants would seem to develop a serious deficiency of DHA if they are fed a formula which has not been fortified with DHA (usually in combination with arachidonic acid). Standard infant formulas contribute about 390 mg/day of alpha-linolenic acid so about 5.2% of this would have to be converted to DHA in order to produce the needed 20 mg/day. The researchers point out that there is no evidence at all that infants are able to achieve this conversion rate and speculate that the rate may be as much as 20 times lower than required. This conclusion is amply supported by the fact that formula-fed infants actually lose 993 mg of DHA over the first 6 months of life while breast-fed babies gain an average of 1882 mg. The accumulation of DHA in the brain of formula-fed infants is only half of that observed in breast-fed infants and while the liver in breast-fed infants gains 24 mg of DHA during the first 6 months the liver in formula-fed ones actually loses 136 mg.
The researchers conclude that feeding infants with a non-fortified formula will not provide the DHA
provided by breast milk. They urge further work to determine whether a formula containing at least 0.2%
DHA (providing 60 mg/day of DHA) will provide equivalent DHA accumulation to that of breast-fed infants.
Docosahexaenoic acid fortifies breast milk
All three forms of DHA supplements produced significant increases in the DHA content of the women's
blood plasma (phospholipid phase) and breast milk. Consumption of two eggs per day over a six-week
period was well tolerated by all participants and had no adverse effects on cholesterol or triglyceride
levels. The DHA level in the blood plasma (phospholipid phase) of the breast-fed infants also increased
significantly over the six-week supplementation period with the infants in groups 1 and 3 having the
largest increases. NOTE: This study was supported by a grant from the Mead-Johnson Nutritional Group.
[61 references]
Infants need long-chain omega-3 fatty acids
Dr. S.E. Carlson of the University of Missouri supports the idea of adding DHA to infant formulas, but
cautions that his fortification should be balanced with an appropriate addition of long-chain omega-6 acids
(arachidonic acid) in order to more closely approximate the composition of mother's milk.
Your brain needs DHA
Docosahexaenoic acid helps brain development
Maternal Fish Oil Supplementation
DHA improves visual acuity in term infants
Now researchers at the University of British Columbia report that maternal DHA supplementation also improves
visual acuity in infants at 2 months of age. The randomized, double-blind, placebo-controlled trial involved 135
pregnant women (average age of 33 years) enrolled at 16 weeks gestation. Half the group was assigned to receive
400 mg/day of a DHA supplement, while the other half received a placebo containing linoleic and alpha-linolenic
acid (265 mg and 40 mg respectively). Blood samples and dietary information were collected at 16 and 36 weeks of
gestation. There were no significant differences in the dietary intake (excluding supplements) of fatty acids between
the DHA group and the placebo group at 16 and 36 weeks. The DHA concentration in maternal red blood cells rose
between weeks 16 and 36 and at week 36 was 32% higher among women in the DHA group.
Visual acuity in the infants was measured at 60 days of age using the Teller Acuity Card Procedure. Results
showed that infants born to mothers in the placebo group were 3 times more likely to have a low visual acuity score
than were children born to DHA-supplemented mothers. The proportion of girls having a higher than average visual
acuity score was also significantly higher among infants born to DHA-supplemented mothers. The researchers
conclude that mothers who do not supplement with DHA during pregnancy have a significant risk of giving birth to
an infant with lower than average visual acuity at 2 months of age.
Fatty acid profile affects birth weight
The study involved 3704 pairs of mothers and newborn infants enrolled in the Amsterdam Born Children and their
Development (ABCD) study. All mothers completed food frequency questionnaires and gave blood samples around
week 12 of their pregnancy. Analysis of the phospholipid phase of blood plasma revealed that mothers with low
concentrations of omega-3 fatty acids and the omega-6 fatty acid, DGLA (dihomo-gamma-linolenic acid or
eicosatetraenoic acid) gave birth to infants with significantly lower birth weights. Women with high levels of other
omega-6 fatty acids and the main trans-fatty acid found in the diet, elaidic acid, also gave birth to infants with lower
birth weights. Similar associations were found for SGA.
After adjusting for possible confounding variables, the researchers conclude that low maternal plasma
concentrations of eicosatetraenoic acid, eicosapentaenoic acid (EPA) and DGLA, and high concentrations of
arachidonic acid are associated with reduced fetal growth, lower birth weight, and a 40-50% increase in risk of SGA.
They suggest that the established beneficial effect of fish oil supplementation (EPA and DHA) on pregnancy
duration, in combination with their own results, points to the importance of fatty acid supplementation as a
preventive option at all phases of pregnancy.
Benefits/risks of maternal seafood consumption
Their study involved 135 women and their infants. The women completed semi-quantitative food frequency
questionnaires at 26-28 weeks of gestation. The questionnaire was specifically designed to determine the
consumption of various types of fish and shellfish. A hair sample was also obtained from the women immediately
after delivery. At about 6 months of age the infants underwent a test (VRM) to determine their visual recognition
memory, a recognized indicator of infant cognition and brain development.
The average fish consumption during the second trimester was 1.2 servings a week and the mean maternal hair
mercury content was 0.55 ppm with 10% of participants having a content above 1.2 ppm. The average VRM score
for the infants was 59.8. after adjusting for possible confounding variables, the researchers concluded that a higher
fish intake is associated with a higher VRM score (better cognition), with one additional fish serving a week
corresponding to a 4.0 increase in VRM score.
On the other hand, a higher maternal hair mercury content was associated with a significantly lower VRM score
(poorer cognition), with a 1ppm increase in mercury corresponding to a decrease of 7.5 in VRM scoring. The
Harvard researchers conclude that women should continue to eat fish during pregnancy, but should choose
varieties with low mercury levels.
Editor's comment: DHA and mercury content vary widely among different species of fish. The most
beneficial and safest is wild salmon with pacific sockeye salmon containing 0 ppm of mercury and 885 mg of DHA
per 100 g serving. Sardines are also an excellent DHA source at 510 mg/100 g and an average mercury content of
0.013 ppm. On the other hand, canned tuna is a relatively poor source of DHA (225 mg/100 g), but a potent source
of mercury (0.340 ppm). Halibut contains somewhat more DHA (375 mg/100 g), but is also fairly high in mercury
(0.2 ppm). Choosing the optimum fish source is clearly important, but an easier solution to ensuring an adequate
DHA intake would be to supplement with a pharmaceutical grade fish oil, which provides high quality DHA and EPA
without any mercury at all.
Maternal DHA supplementation helps infant’s problem solving
The double-blind, placebo-controlled trial included 29 women who were randomized to receive 5 DHA-fortified cereal bars a week (providing 214 mg/day of DHA and 27 mg/day of EPA) or placebo bars (containing corn oil) from week 24 of gestation to delivery. The women in the DHA group tended to give birth 1 week later than those in the placebo group and there was also a trend for their infants to be slightly taller.
At 9 months of age the infants participating in the trial were exposed to a problem-solving test involving finding and retrieving a toy. The infants born to mothers who had supplemented with DHA scored significantly higher on this test than did infants born to mothers who had not supplemented. A recognition memory test was also administered, but no differences in results were observed between the two groups. The researchers conclude that DHA supplementation during pregnancy has a beneficial effect on the infant’s problem-solving skills at 9 months of age.
Maternal fish oil supplementation benefits children
Supplementing with fish oils (DHA) is known to cause a reduction in the availability of arachidonic acid and, since ARA is also required for brain development, there is some concern that supplementation with large doses of fish oil may reduce ARA availability to such an extent as to be detrimental.
Researchers at the University of Western Australia addressed this concern in a clinical trial involving 83 pregnant women. The women were randomized to receive placebo (olive oil) or fish oil (providing 1.1 gram/day of EPA and 2.2 grams/day of DHA) from 20 weeks’ gestation until birth. An analysis of phospholipid fatty acids from erythrocytes (red blood cells) in cord blood of newborns found that infants born to fish oil supplemented mother had a 225% higher EPA (eicosapentaenoic acid) content in their blood than did those born to control mothers. DHA content was 39% higher and ARA content 15% lower.
The effects on infants’ growth and brain development were evaluated at age 2.5 years. No significant differences were found in height, weight, and head circumference between children born to mothers who had supplemented with fish oil and those born to mothers in the placebo group. There was, however, a difference in eye and hand coordination between the two groups with children born to supplemented mothers performing significantly better when measured using the Griffiths Mental Development Scale. The researchers also noted a significantly higher level of EPA and DHA (and a lower level of ARA) in the cord blood of children with superior eye and hand coordination. The researchers conclude that maternal fish oil supplementation during pregnancy is safe for the fetus and infant, and may have potentially beneficial effects on the child’s eye and hand coordination.
Fish oil supplementation during pregnancy is safe
Infant Development
Omega-3 fatty acids and child development
Dr. Emily Oken and colleagues at the Harvard Medical School studied over 25,000 children of mothers participating
in the Danish National Birth Cohort, a prospective population-based study that enrolled pregnant women between
1997 and 2002. Data was collected on maternal fish intake, the duration of breastfeeding and measures of child
development milestones. The primary outcome was total development at 18 months ascertained by an interview.
Mothers were questioned about whether the child could climb stairs, remove socks and shoes, drink from a cup, be
occupied for 15 minutes with adult participation, fetch an object when requested, write or draw, orient a book
correctly, use word-like sounds, and put two words together. Ages at which the child could first sit unsupported and
could walk unassisted and the total number of words the child could correctly say was recorded. Data was also
collected at 6 months with an appropriate set of questions. From this data scales were constructed and scores
derived. Other data collected included birth weight and evidence of early or late delivery (gestational age), maternal
smoking and alcohol use and other information which allowed correcting for confounding. It was found that higher
maternal fish intake during pregnancy and the duration of breastfeeding were associated with higher child
development scores at 18 months. For example, 5.7% of children with a mother in the lowest quintile of fish intake
had the lowest total development score at 18 months whereas only 3.5% of children with their mother in the highest
quintile of fish intake had the lowest total development score. Women in the lowest quintile consumed < 1 fish
serving/week whereas in the highest quintile it was about 3.5 servings/week. Fish most frequently consumed were
cod, plaice, salmon, herring and mackerel. Species with high mercury content are not commonly consumed in
Denmark.
Longer duration of breastfeeding was associated with better development at 18 months. After adjusting for maternal
fish intake, longer breast-feeding remained associated with a greater achievement of developmental milestones
with a 28% increase when = 10 months was compared with = 1 month. This pattern of association with fish intake
and duration of breastfeeding was a robust result which persisted after a number of different corrections for
potential confounding.
The authors comment that in the U.S. and Europe, expert panels have advised that pregnant women consume a
minimum of 200 mg/day of DHA. They point out that most women do not consume this much DHA from fish or other
dietary sources, and thus supplements may offer a reasonable alternative. They cite studies which found improved
development in children of women randomly assigned to take supplemental DHA although doses were much higher
(1-2 g/day) than the experts recommended. The authors cite evidence that in the case of the long-chain
polyunsaturated fatty acids, supplementation with a single acid may be less desirable than providing a more natural
balance of these nutrients. Fish oil, for example contains both DHA and EPA.
DHA improves visual acuity in term infants
Now researchers at the University of British Columbia report that maternal DHA supplementation also improves
visual acuity in infants at 2 months of age. The randomized, double-blind, placebo-controlled trial involved 135
pregnant women (average age of 33 years) enrolled at 16 weeks gestation. Half the group was assigned to receive
400 mg/day of a DHA supplement, while the other half received a placebo containing linoleic and alpha-linolenic
acid (265 mg and 40 mg respectively). Blood samples and dietary information were collected at 16 and 36 weeks of
gestation. There were no significant differences in the dietary intake (excluding supplements) of fatty acids between
the DHA group and the placebo group at 16 and 36 weeks. The DHA concentration in maternal red blood cells rose
between weeks 16 and 36 and at week 36 was 32% higher among women in the DHA group.
Visual acuity in the infants was measured at 60 days of age using the Teller Acuity Card Procedure. Results
showed that infants born to mothers in the placebo group were 3 times more likely to have a low visual acuity score
than were children born to DHA-supplemented mothers. The proportion of girls having a higher than average visual
acuity score was also significantly higher among infants born to DHA-supplemented mothers. The researchers
conclude that mothers who do not supplement with DHA during pregnancy have a significant risk of giving birth to
an infant with lower than average visual acuity at 2 months of age.
Fish consumption during pregnancy
After adjustments for confounding, maternal seafood intake during pregnancy of less that 340 g/week was associated with increased risk of the children in question being in the lowest fifth for verbal IQ and in addition there was a significant trend to greater risk as the seafood consumption declined to zero. Low maternal seafood intake was also associated with increased risk of suboptimal outcomes for development in the areas of social behavior, as well as motor, communication and social development, and for each outcome the lower the fish intake the higher the risk for suboptimal development. The authors conclude that maternal seafood consumption of less than 340 g/week did not protect children from adverse neural development, and that in fact intake exceeding 340 g/week (12 oz or 3/4 lb) resulted in beneficial effects on child development. Thus the authors conclude that following the guidelines could actually be detrimental, and that the results suggest that the benefits from eating more than 340 g of seafood per week outweighed the risk of harm from exposure to trace contaminants.
Fish oils improve IQ in children
A total of 341 pregnant women took part in the study. They were randomized to receive 2 teaspoons (10 ml) per day of cod liver oil or the same amount of corn oil from the 18th week of pregnancy to 3 months after delivery. To be accepted into the study, the women also had to declare their intention of breastfeeding their infant. The fish oil (cod liver oil) provided 1200 mg/day of DHA (docosahexaenoic acid) and 800 mg/day of EPA (eicosapentaenoic acid). The breast milk of mothers receiving the fish oil supplement contained almost 3 times as much DHA as did the breast milk of mothers receiving corn oil.
At 4 years of age, 84 children had their IQ tested using the Kaufman Assessment Battery for Children (K-ABC). The children whose mothers had supplemented with fish oil and who had been breastfeed for at least 3 months after birth scored an average of 4 points higher on the K-ABC scale. The researchers point out that this increase is highly significant in overall terms and would be difficult to attain through normal teaching procedures.
Fish consumption and pregnancy outcome
Mothers' fish oil supplementation benefits infants
Researchers at the Oregon Health Sciences University recently set out to answer the question "Do high
intakes of DHA by pregnant women increase the DHA level in their newborn infants?" Their clinical trial
involved 31 healthy, pregnant women 15 of whom were assigned to receive 2.6 grams/day of omega-3
fatty acid from fish (1.01 grams DHA/day) from their 26th to their 35th week of pregnancy. The remaining
women served as controls. The fish oil supplement was taken as a combination of tinned sardines and
fish oil capsules; either 1 half tin of sardines plus 7 fish oil capsules per day, 1 tin of sardines (3 3/4 oz)
plus 3 fish oil capsules per day or 10 fish oil capsules (10 grams) per day. Blood samples were collected
from mothers at entry to the study, monthly after entry and at delivery, and from the infants at delivery.
The level of DHA in the red blood cells of supplemented mothers rose from 4.69% (of total fatty acids) at
entry to 7.15% at the end of week 34 and then declined (as expected) to 5.97% at delivery. DHA
increases in the blood plasma paralleled the increase in the red blood cells, but at a lower level. DHA
levels in newborn infants differed greatly depending on whether the mothers had supplemented or not.
Red blood cell levels in infants born by supplementing mothers were 35.2% higher than in the control
infants and blood plasma levels were 45.5% higher (5.05% vs. 3.47%).
The researchers believe that supplementing pregnant mothers with fish oil may benefit brain and retinal
development in their offspring particularly if born prematurely. They point out that supplementing from
mid-pregnancy to the 34th week is perfectly safe and may reduce the incidence of preeclampsia
(pregnancy-related high blood pressure) as well.
Post-partum Depression
Pilot trial of fish oil for post-partum depression
Their 8-week pilot study involved 16 women with PPD. The extent of depression was evaluated using the Edinburgh Postnatal Depression Scale (EPDS) and the Hamilton Rating Scale for Depression (HRSD). The EPDS scores ranged from 15.3 to 19.0 at the start of the study (a score equal to or greater than 9.0 indicates depression). The HRSD scores ranged from 18 to 20.3 with a score equal to or greater than 15 signifying depression.
The study participants were randomized to receive placebo capsules (corn oil + 1% fish oil) or 0.5, 1.4 or 2.8 grams/day of a fish oil having an EPA:DHA ratio of 1.5:1 (EPAX 5500, Pronova, Lysker, Norway) for 8 weeks. The participants were followed up and checked for depression scores at weeks 1, 2, 4, 6, and 8. At week 8 the average EPDS score had decreased to 9.3 (a 51.5% reduction) and the HRSD score had fallen by 48.8% to an average of 10 in the fish oil groups. Improvement was most noticeable in the group receiving 1.4 grams/day of EPA + DHA and no advantage was seen by taking 2.8 grams/day. However, just 0.5 gram/day also was successful in reducing both EPDS scores and HRSD scores to normal (non-depressed) levels. The researchers conclude that fish oil supplementation in women with PPD is well tolerated and effective in reducing symptoms of depression.
Fatty acid status and post-partum depression
Their study included 48 healthy, pregnant women who had blood samples taken shortly after delivery. These blood samples were analyzed to determine the fatty acid profile in serum phospholipids (PL) and cholesteryl esters (CE). The women were also interviewed within 6 to 10 months after delivery to ascertain whether they suffered from PPD. Ten of the women (21%) had indeed developed PPD with most reporting depressive symptoms immediately following delivery. Analyses of the blood samples showed that DHA concentration and total omega-3 level were significantly lower in both the PL and CE fractions of blood serum taken from women who developed PPD.
The Dutch researchers speculate that the milder form of PPD, post-partum blues, also is related to a fatty acid imbalance and is currently investigating this in a separate study involving 98 women. They conclude that pregnant women at risk for developing PPD may benefit from preventive supplementation with DHA, perhaps in combination with its precursor docosapentaenoic acid.
Post-partum depression and functional DHA status
The Dutch study involved 112 pregnant women who had blood samples collected at week 36 of pregnancy, immediately following delivery, and 32 weeks post-partum. At week 32 post-delivery the women were assessed for the presence of PPD using the Edinburgh Postnatal Depression Scale (EPDS) questionnaire. Twenty-four of the women (21%) were found to suffer from depression (EPDS score equal to or greater than 10). Seventy-five percent of the depressed women rated themselves as “not healthy” in the months following delivery as compared to only 6% in the non-depressed group (EPDS score less than 10).
The researchers did not observe any statistically significant relationship between post-partum depression and DHA level as such; however, they did find a significant correlation between PPD and the increase in DHA:DPA ratio between delivery and 32 weeks post-partum. Women with a slower increase in this ratio had a 10% higher risk of PPD. There was no indication that breast-feeding increased the risk of PPD. The researchers recommend further studies, but suggest that women who have recently given birth increase their intake of DHA.
Post-partum depression linked to DHA deficiency
Dr. Hibbeln evaluated the results of 41 relevant studies involving over 14,000 women located in 23 different countries. He compared the incidence of post-partum depression in new mothers in each country with the average seafood consumption and average DHA concentration in the mothers’ milk in the country. The results were remarkable. Dr. Hibbeln found a clear correlation between the incidence of PPD and seafood consumption. The highest incidence of PPD (24.5%) was found in South Africa, which also reported the lowest seafood intake at 8.6 lb/person/year. In comparison, Japan reported a PPD incidence of only 2% and an average seafood consumption of 147.7 lb/person/year. In the United States average seafood intake amounted to 48.1 lb/person/year with a corresponding PPD incidence of 11.5%. Numbers for Canada were similar at 50.7 lb/person/year seafood consumption and 12.7% PPD.
Analyses of fatty acid content of mothers’ milk were available for 16 countries. While there was no correlation between PPD and the content of arachidonic acid and eicosapentaenoic acid, there was a clear correlation between PPD and low DHA level. South Africa reported the lowest DHA content (0.15% of total fats in mothers’ milk) and the highest PPD incidence at 24.5%. The average DHA level in mothers’ milk in Japan was 0.81% versus a PPD incidence of 2%. Average DHA level in the USA was 0.17% (PPD incidence of 11.5%).
Although there are clearly other factors predisposing to post-partum depression, Dr. Hibbeln found that the effects of low socioeconomic status, young maternal age, no partner, and poor education were minor when compared to the effect of seafood consumption and low DHA status. He points out that numerous studies have shown that DHA status can be safely and effectively improved by supplementation with fish oil. Specifically, studies have found that supplementation with 1.1 gram/day of DHA will increase breast milk concentration to 0.8% without any adverse effects. A level of 0.8% is equivalent to the average level observed in Japan and is associated with a low 2.0% risk of PPD.
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Additional References
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