Large study from Norway affirms indications that vitamin D may help prevent preeclampsia; other studies point to omega-3s as possible anti-preeclampsia agents
by Craig Weatherby

A dangerous condition of pregnancy called preeclampsia affects up to eight percent of first-time mothers in the U.S., and up to 18 percent of pregnancies in poor countries.

Preeclampsia (pree-eh-clamp-see-ah) is responsible for up to 75,000 annual deaths worldwide, and remains a leading cause of mother and baby mortality rates and infant health problems worldwide.

Key Points
  • Large population study links higher vitamin D intakes to reduced risk of preeclampsia.
  • Omega-3s show similar potential in prior studies.
  • These indications must be confirmed by clinical trials.
This potentially deadly condition can involve an abrupt rise in blood pressure, leaking of protein into urine, headaches, and swelling of the hands, feet, and face.

Typically, preeclampsia occurs in middle to late pregnancy, though it can occur earlier (For more about the warning signs, visit the Preeclampsia Foundation).

Uncertain explanations and remedies
The exact causes of preeclampsia remain unclear, although researchers suspect poor nutrition, high body fat, immune deficiencies, and insufficient blood flow to the uterus, with ethnicity and heredity seen as possible factors.

Hopes have been raised for a number of possible preventive factors
including antioxidant vitamins and chocolatebut these indications were not supported by subsequent research (Triche EW et al. 2008; Rumbold A et al. 2008; Klebanoff MA et al. 2009).

Two years ago, we summarized studies that found vitamin deficiency common among pregnant American women and linked this vitamin D lack to increased risk of preeclampsia.

For more on those studies and the condition itself, see “Pregnancy Danger Linked to Low Vitamin D Levels.

Let's take a look at the new findings on vitamin D… and examine evidence that omega-3s may also help deter this rare but potentially deadly condition.

Vitamin D linked to lower preeclampsia risk in large study
A study involving more than 23,000 Norwegian women affirms prior indications that increased intakes of vitamin D may reduce preeclampsia risks for first-time mothers (Haugen M et al. 2009).

Norwegian researchers asked participants to answer a general health questionnaire at the 15th week of pregnancy and again at the 30th week, and they administered a diet questionnaire at week 22.

Compared to women who consumed less than 200 IU per day, the risk of preeclampsia was 24 percent lower in women who consumed from 400 to 600 IUs of vitamin D from foods and/or supplements daily.

A slightly bigger risk reduction of 27 percent was seen among women who got 400 to 600 IUs of vitamin D daily from supplements, compared to women who did not take vitamin D supplements.

As the Norwegian team wrote, “These findings are consistent with other reports of a protective effect of vitamin D on pre-eclampsia development” (Haugen M et al. 2009).

The researchers also noted that the women who reported higher vitamin D intake also reported higher omega-3 intake (from food and/or pills). This makes sense, given that fish are by far the best food sources of both nutrients.

As they wrote, “further research is needed to disentangle the separate effects of these nutrients” (Haugen M et al. 2009).

In fact, prior research has linked diets higher in omega-3s to reduced risk of preeclampsia.

Omega-3s may help prevent preeclampsia
Many women with preeclampsia display some of the same artery problems associated with cardiovascular disease:
  • High blood pressure
  • Endothelial (artery lining) dysfunction
  • Poor blood flow to the extremities
  • Overly “sticky” blood
  • Antioxidant deficiency
  • Chronic inflammation in the blood and arteries
  • High blood fat (triglyceride) levels.
Coincidentally, most evidence suggests that the omega-3 fatty acids from fish help reduce blood triglyceride levels, blood stickiness, and blood pressure, while improving the performance of artery walls and blood-flow dynamics (Williams MA et al. 1995; Habon T et al. 2002).

As with the current vitamin D study, that evidence that omega-3s may help comes from epidemiological studies, in which researchers compare people's habits with their health status.

While such studies can demonstrate statistical associations between a drug or nutrient and reductions in the risk or severity of a disease, they cannot prove a cause-and-effect connection.

Teams led by Dr. Michelle A. Williams of Seattle's renowned Swedish Medical Center, conducted three epidemiological studies – one in the U.S., one in Peru, and one in Zimbabwe.

All three studies linked low blood levels of omega-3 fatty acids to an increased risk of preeclampsia (Williams MA et al. 1995; Qiu C et al. 2006; Mahomed K et al. 2007).

And two of these studies (Qiu C et al. 2006; Mahomed K et al. 2007) also linked high blood levels of trans fats and omega-6 fats (particularly arachidonic acid) to increased risk of preeclampsia.

Omega-6 arachidonic acid is essential to health and to child development, but the American diet contains far too many omega-6 fats, which tend to promote inflammation.

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  • Grill S, Rusterholz C, Zanetti-Dällenbach R, Tercanli S, Holzgreve W, Hahn S, Lapaire O. Potential markers of preeclampsia--a review. Reprod Biol Endocrinol. 2009 Jul 14;7:70. Review.
  • Habon T, Kesmarky G, Toth K. Omega-3 fatty acids improve haemodynamic and haemorheologic parameters and lipid profiles in patients with cardiovascular diseases. Eur Heart J. 2002 Jan;23(1):89.
  • Haugen M, Brantsaeter AL, Trogstad L, Alexander J, Roth C, Magnus P, Meltzer HM. Vitamin D supplementation and reduced risk of preeclampsia in nulliparous women. Epidemiology. 2009 Sept Vol20, Issue 5, Pages 720-726. [pub med]
  • Klebanoff MA, Zhang J, Zhang C, Levine RJ. Maternal serum theobromine and the development of preeclampsia. Epidemiology. 2009 Sep;20(5):727-32.
  • Mahomed K, Williams MA, King IB, Mudzamiri S, Woelk GB. Erythrocyte omega-3, omega-6 and trans fatty acids in relation to risk of preeclampsia among women delivering at Harare Maternity Hospital, Zimbabwe. Physiol Res. 2007;56(1):37-50. Epub 2006 Feb 23.
  • Qiu C, Sanchez SE, Larrabure G, David R, Bralley JA, Williams MA. Erythrocyte omega-3 and omega-6 polyunsaturated fatty acids and preeclampsia risk in Peruvian women.Arch Gynecol Obstet. 2006 May;274(2):97-103. Epub 2006 Mar 7.
  • Rumbold A, Duley L, Crowther CA, Haslam RR. Antioxidants for preventing pre-eclampsia. Cochrane Database Syst Rev. 2008 Jan 23;(1):CD004227. Review.
  • Triche EW, Grosso LM, Belanger K, Darefsky AS, Benowitz NL, Bracken MB. Chocolate consumption in pregnancy and reduced likelihood of preeclampsia. Epidemiology. 2008 May;19(3):459-64.
  • Williams MA, Zingheim RW, King IB, Zebelman AM. Omega-3 fatty acids in maternal erythrocytes and risk of preeclampsia. Epidemiology. 1995 May;6(3):232-7.