Preeclampsia is a serious complication that affects pregnant women, marked by high blood pressure and organ damage, and can endanger maternal and infant health. While it can occur without warning, researchers believe that nutritional deficiencies may play a role in its development. As treatment options are limited once preeclampsia develops, preventing it is a major focus of medical research. A recent Japanese review study explored whether dietary supplements—such as vitamins and minerals—could be effective in reducing the risk of preeclampsia. The study included evaluations of various supplements, with a particular focus on calcium and vitamin D. It found that while only a few supplements had strong evidence of benefit, calcium supplementation stood out as an effective way to lower the risk of preeclampsia.

Preeclampsia remains one of the leading causes of complications during pregnancy, especially when it comes to early births and health challenges for newborns. One reason for its persistence is that the exact cause is still not fully understood. However, poor nutritional intake—particularly of certain vitamins and minerals—has been linked to an increased risk. Many pregnant women, especially in regions where diets may lack essential nutrients, are not consuming enough of the recommended daily nutrients.

To examine the possible preventive role of dietary supplements, a review study from Japan analyzed existing research on a wide range of vitamins, minerals, amino acids, and antioxidants. The study looked at whether any of these supplements could effectively reduce the risk of developing preeclampsia during pregnancy.

Calcium Proves to Be the Most Effective Supplement

The review found that calcium supplementation during pregnancy significantly reduces the risk of developing preeclampsia—especially in populations with low calcium intake. Even a low daily dose of 500 mg was shown to halve the risk. This is especially relevant in Japan, where the average calcium intake among women is far below recommended levels. While some global guidelines suggest higher doses, the study highlighted that lower amounts can still offer strong preventive benefits, with fewer concerns about side effects.

In addition to calcium, the study examined other supplements like vitamin D, magnesium, omega-3 fatty acids, and folic acid. The evidence for these was either inconsistent or limited. For vitamin D, some studies showed a reduced risk, while others found no benefit. As a result, the researchers concluded that vitamin D could be promising, but further large-scale studies are needed to confirm its effectiveness.

A Simple Step with Meaningful Impact

For pregnant women or those planning to conceive, ensuring adequate calcium intake could be a simple and effective way to reduce the risk of preeclampsia. In regions where calcium intake is typically low, supplements can play a key role in supporting a healthy pregnancy. While other supplements may offer benefits, only calcium showed consistent and strong results across multiple studies.

Preventive care during pregnancy is essential to protect both maternal and newborn health. Addressing basic nutritional needs may be one of the most accessible and impactful ways to reduce the risk of complications like preeclampsia.

Paper available at: Dietary supplements and prevention of preeclampsia
Full list of authors: Ushida, T.; Tano, S.; Matsuo, S.; Fuma, K.; Imai, K.; Kajiyama, H.; Kotani, T.
DOI: https://doi.org/10.1038/s41440-025-02144-9