Horsetail, or Equisetum arvense, is a fern that resembles asparagus. Its aboveground parts are used for medicinal reasons, most commonly as a diuretic in the cases of kidney stones or urinary tract infections and to strengthen bones in the case of osteoporosis. People also use it to treat brittle nails and apply it topically to treat burns. Forms of use are liquid preparations or dried herbs used to make tea. Horsetail is considered unsafe for use while pregnant or breastfeeding.
Vitamin B1
The oral use of horsetail can cause vitamin B1 levels to drop because it contains thiaminase, a chemical that breaks down thiamine, or vitamin B1. A thiamine deficiency can cause fatigue, weakness, nerve damage and psychosis. Pregnant and breastfeeding women need higher levels of thiamine than the Recommended Dietary Allowance of 1.1 milligrams per day. A pregnant or breastfeeding mother may think she is getting the proper amount of vitamin B1 from a diet of eggs, enriched bread, legumes, whole grains, peas and nuts, but consuming horsetail can undermine her efforts.
Potassium
Horsetail, because of its diuretic properties, can lead to lowered potassium levels because the kidneys excrete potassium in urine. Horsetail, taken with aloe latex or senna, can also lower potassium levels. Both aloe latex and senna can help with constipation, a problem that affects about half of pregnant women at some point during the pregnancy. But like horsetail, aloe and senna should also be avoided during pregnancy or breastfeeding. Women do not need extra potassium while pregnant, but they should maintain adequate levels to reduce the risk of hypertension.
Autism
A case study that took place in Spain, published in the March 2011 issue of the “Journal of Medical Case Reports,” showed that use of horsetail could have led to a patient’s giving birth to an autistic child. The 32-year-old mother ingested 1,200 milligrams of horsetail a day as a weight loss aid because of the diuretic properties of horsetail. It was consumed a year before conception and continued until her child was 3 years old. The mother lost weight during her pregnancy despite getting enough calories from food. Her child was diagnosed with autism and mild mental retardation. Researchers believe the excessive use of horsetail led to the patient not getting enough thiamine and folic acid during pregnancy and lactation, which could have been a factor in the diagnosis of autism in her child.
Pregnancy
Neurodevelopmental disorders are most likely to occur from just before conception to two to six weeks after gestation. Many women do not realize they are pregnant during this period. Because the relationship between horsetail and pregnancy is likely harmful because of the increased likelihood of vitamin deficiency, women who are of childbearing age should avoid horsetail.
References
- MedlinePlus; Horsetail; July 2011
- "The New York Times"; Thiamin; February 2011
- American Pregnancy Association; Natural Herbs & Vitamins During Pregnancy; July 2011
- American Pregnancy Association; Pregnancy and Constipation; March 2007
- St John Providence: Potassium
- "Journal of Medical Case Reports"; Prenatal Exposure of a Girl with Autism Spectrum Disorder to 'Horsetail' (Equisetum Arvense) Herbal Remedy and Alcohol; Juan A Ortega García, et al.; March 2011
