The video shows the 35-year-old actress chewing up food for her 10-month-old son, Bear Blu, and then spitting it into his mouth.
The Clueless star posted on her health food blog, The Kind Life: “I just had a delicious breakfast of miso soup, collards and radish steamed and drizzled with flax oil, cast iron mochi with nori wrapped outside, and some grated daikon. Yum!
“I fed Bear the mochi and a tiny bit of veggies from the soup… from my mouth to his.
“It’s his favourite…and mine.
“He literally crawls across the room to attack my mouth if I’m eating. This video was taken about a month or 2 ago when he was a bit wobbly. Now he is grabbing my mouth to get the food!”
Dr Jennifer Landa, chief medical officer of BodyLogicMD told Fox News: “There are those who think that a mum chewing a baby’s food provides helpful enzymes from her mouth but it doesn’t seem like a hygienic practice. Various viruses and bacteria, but especially herpes virus, may be passed from mother to baby.
“These microbes present a challenge that the infant’s immune system may not be ready for. So the practice is questionable for safety, and then, there’s a certain ick factor here that needs to be considered,”
Silverstone, who is married to singer and radio presenter Christopher Jarecki, is a committed vegan and is bringing up her son to follow the same diet.