Know anything about Grapefruit Seed Extract?

A midwife recently told me to take Grapefruit Seed Extract to help boost my immune system while pregnant (due to the recent flu outbreaks and me asking her how to stay healthy in spite of them). So my husband, who works at an herbal distributor, buys some for me. His boss and a co-worker tell him that it’s not safe to ingest. I did further research and can’t find anything that suggests it’s bad. The people he works with are highly herb knowledgeable so now I’m confused. Does anyone know about this product?

I will be asking my doctor before I take it but that is about a month away so I thought I’d do some research myself beforehand. It’ll probably confuse me even more to hear what everyone thinks but hey I like having as much info. as possible.