Natural Ingredients in Pregnancy and Breastfeeding
What sources say about castor oil, raw milk, clay, kelp, colloidal silver, black seed and baking soda in pregnancy and breastfeeding, and where no pregnancy evidence was found.
Content last updated . This page has not been medically reviewed.
Safety first. Natural products can cause side effects and interact with medicines. Read natural ingredient safety before you use anything on this page.
Pregnant or breastfeeding, and worried about something you swallowed? Call Poison Help at 1-800-222-1222 (US); the line is free and open at any hour. [1] Call 911 for collapse, a seizure or trouble breathing. [2] Ask your midwife, obstetrician or pharmacist before using any concentrated natural product. This page is information, not advice for one person.
NCCIH notes that many dietary supplements have not been tested in pregnant women, nursing mothers or children. [3] For most natural ingredients, we did not find pregnancy-specific safety studies, so the table says "Proper evidence not found" rather than implying safety. Honey for babies is a different question; see babies and children.
What the sources we read say
| Ingredient | What the sources we read say | Evidence label |
|---|---|---|
| Castor oil by mouth, to start labor | A Cochrane review found three small trials (233 women); all women who swallowed it felt nauseous; no data on mother or baby outcomes. [4] | Insufficient evidence; nausea documented |
| Raw (unpasteurized) milk | A review of outbreaks urges pregnant women to know about Listeria risk in high-risk foods. [5] | Evidence of harm (outbreak data) |
| Eating clay (geophagy) | Common in pregnancy in parts of Africa and Asia; safety not established; toxic metals reported in clays. [6][7][8] | Insufficient evidence; contamination reported |
| Kelp and iodine supplements | The American Thyroid Association says pregnant and lactating women are susceptible to the effects of excess iodine. [9] | Professional-society statement |
| Colloidal silver | LactMed says it should not be used during breastfeeding. [10] | No good evidence of benefit |
| Black seed | No excretion data for breast milk; no valid trials for increasing milk. [11] | Insufficient evidence |
| Baking soda | MedlinePlus drug information says to tell your doctor if you are pregnant or breastfeeding. [2] | Drug-label guidance |
| Honey (adult), apple cider vinegar, bee products | Proper evidence not found. We searched PubMed for honey and pregnancy safety and found no usable source. | Insufficient evidence |
Castor oil and labor
Castor oil is a potent cathartic, a strong laxative, made from the castor bean. [4] The Cochrane review could not detect all but large differences in outcome because the trials were small. [4] It reported no data on newborn or maternal illness. [4] Our page on castor oil covers this in more detail. Do not use it to start labor without your care team's guidance.
Seaweed, kelp and iodine
The American Thyroid Association advises against iodine and kelp supplements containing more than 500 mcg of iodine daily, including during pregnancy and lactation. [9] See Seaweed, iodine and the thyroid.
Breastfeeding
LactMed says colloidal silver should not be used during breastfeeding because it has no proven benefit. [10] For black seed, LactMed found no excretion data and no valid trials supporting its use to increase milk, and it says limited information indicates black seed is generally well tolerated. [11] For other ingredients we could not read a LactMed entry. Ask a lactation-aware clinician.
Where to read more and what to do
- Pregnancy and breastfeeding: supplements and herbs
- Breastfeeding: herbs and supplements, LactMed explained
- Tell every clinician what you use, including home remedies, and see how to check an interaction.
Frequently asked questions
Is raw honey safe in pregnancy?
Proper evidence not found. We searched PubMed and found no source on honey in pregnancy. The honey rule in sources is for babies under 12 months. [13]
Is castor oil safe to start labor?
A Cochrane review found small trials with nausea in every woman and no data on newborn outcomes. [4] Ask your care team.
Is it safe to eat clay while pregnant?
No source we read says it is. Reviews report toxic metals in clays and limited evidence on fetal outcomes. [8]
Can I take kelp or iodine supplements while breastfeeding?
The American Thyroid Association advises against kelp or iodine supplements above 500 mcg iodine daily, including in lactation. [9]
Is raw milk safer if it is organic?
We did not find a source that compares it. The outbreak review concerns unpasteurized products in general. [5]
More details: evidence, limits and cautions
The details behind this page: cautions, limits of the evidence and where sources disagree. Open any note to read it.
Raw milk and food safety
The review of dairy outbreaks in Canada and the United States counted 20 outbreaks linked to unpasteurized products: 449 confirmed cases, 124 hospitalizations and five deaths. [5] It recommends that pregnant women and immunocompromised people know which foods carry Listeria risk. [5] See raw milk claims checked.
Eating clay during pregnancy
A review notes that eating calabash chalk is notably common among pregnant women in parts of Africa and Asia. [6] Another notes limited evidence linking clay eating to fetal outcomes. [8] MedlinePlus says pica, eating non-food materials such as dirt, can occur in pregnancy, and that a lack of nutrients such as iron and zinc may trigger the cravings. [12] If you crave clay or similar items, tell your care team. See substances not meant to be swallowed.
References
- MedlinePlus Medical Encyclopedia. Hydrogen peroxide poisoning. National Library of Medicine. Read 2026-10-23.
- MedlinePlus Drug Information. Sodium Bicarbonate. Last revised 04/15/2017. Read 2026-10-23.
- National Center for Complementary and Integrative Health (NIH). Using Dietary Supplements Wisely. Read 2026-10-23.
- Kelly AJ, Kavanagh J, Thomas J. Castor oil, bath and/or enema for cervical priming and induction of labour. Cochrane Database Syst Rev. 2013;(7):CD003099. Abstract read 2026-10-23.
- Sebastianski M, et al. Disease outbreaks linked to pasteurized and unpasteurized dairy products in Canada and the United States: a systematic review. Can J Public Health. 2022;113(4):569-578. Abstract read 2026-10-23.
- Makinde OW, et al. Geophagia among pregnant women: evaluating the microbiological and toxicological safety of calabash chalk. Environ Geochem Health. 2025. Abstract read 2026-10-23.
- Bonglaisin JN, et al. Geophagia: Benefits and potential toxicity to human, a review. Front Public Health. 2022;10:893831. Abstract read 2026-10-23.
- Lawluvi H, et al. Maternal geophagy in Ghana: a mini review of toxicological, microbial, nutritional, and radiological exposure pathways. Front Public Health. 2026. Abstract read 2026-10-23.
- American Thyroid Association. ATA Statement on the Potential Risks of Excess Iodine Ingestion and Exposure. Posted June 5, 2013; page shows March 2024. Read 2026-10-23.
- Drugs and Lactation Database (LactMed). Colloidal Silver. National Institute of Child Health and Human Development; entry dated 2026 Mar 15. Read 2026-10-23.
- Drugs and Lactation Database (LactMed). Black Seed. National Institute of Child Health and Human Development; entry dated 2025 Jul 15. Read 2026-10-23.
- MedlinePlus Medical Encyclopedia. Pica. National Library of Medicine. Read 2026-10-23.
- Tanzi MG, Gabay MP. Association between honey consumption and infant botulism. Pharmacotherapy. 2002;22(11):1479-83. Abstract read 2026-10-23.