The TV star, who had been a vegetarian up until that point, told Suffolk Norfolk Life that she "cried for three days" after coming to the realisation about how cow's milk is produced and the impact it has on the animals.
Jasmine shares son Albion and daughter Joy with husband and cameraman Jon Boast. Speaking of her little girl, she recalled: "I was really wanting to breastfeed her, but I was struggling with it. I was upset and thinking to myself why do cows produce milk for no reason, and I can't produce any milk for my baby?
WATCH: See inside Jasmine Harman's vegan living room
"I began to think about it and it suddenly dawned on me at the age of 38 that the cow only produces milk when she has had a baby.
"That made me stop and think what happens to her baby? I did some research and from that moment on I could not have dairy again. It was such a shock and so upsetting I think I cried for three days. I've been vegetarian for most of my life as I don't want to harm animals and realised that by eating dairy, I was doing just that."
The TV star revealed her daughter Joy helped prompt her diet change
But it wasn't a simple transition for Jasmine, who revealed there was one particular food she struggled to part with – cheese.
"I had it with everything. Cheese made a meal for me when I was a vegetarian. Now my palate has changed so much I don't even miss it. I can actually smell it and all I can smell is fat, grease and gone-off milk," Jasmine continued.
Jasmine often shows off her tasty vegan dishes on Instagram
The 45-year-old credits her new diet for helping her lose over 20lbs, boosting her energy levels and improving her complexion.
She told Your Healthy Living: "I don’t think I would have coped as well with the last four years of interrupted sleep (as a mum of small children who don’t like sleeping) without the energy boost I get from my vegan diet.
"I lost all my baby weight much sooner after my second pregnancy (as a vegan). I was back in my jeans after two to three weeks! My skin is much more naturally glowing and youthful."