Dairy alternatives are on the up and up, and perhaps none more so than almond milk. The nut-based milk is not milk at all, but a liquid formed from the soaking of nuts and water. Popular in coffee, smoothies and poured over cereals (alongside cousins coconut, macadamia, rice, and oat milk) almond milk is booming in trade.

But is it as good for us as we think? Yes and no says Dr Michael Mosley, who stars on the SBS show Trust Me, I’m A Doctor. While he has no problem with dairy alternatives as a whole, Mosley points out that there is one key supplement that almond milk lacks that is causing an issue for women in particular worldwide.

“One of the very striking things we did discover in this new season of Trust Me, I’m A Doctor is that an awful lot of women are now iodine deficient and the reason for that, certainly in the UK, [is that] the major source of iodine is milk. A lot of women are shifting from drinking cow’s milk to almond milk and other alternatives that have around 1-2 percent of the iodine content of cow’s milk.”

Why is iodine important? Predominantly for healthy thyroid function. “Iodine is really important for keeping your thyroid in good condition otherwise you can be hypothyroid and put on weight. It’s particularly important for pregnant women because iodine is essential for the development of the foetal brain,” Mosley explains. “Because so many people are switching from cow’s milk we now have somewhat of an epidemic of iodine deficiency in young women.”

But there’s no need to stress; iodine deficiency is both easy to spot and to treat. “You can get your iodine status checked if you’re worried,” says Mosley. And then reassess your diet, and current supplements. “There are some multivitamins that have iodine in them but most of them don’t. Another good source of iodine, if you don’t like milk, is white fish or seaweed, although in seaweed the doses can be very high.”

There is also the option of buying an iodised salt. “In many countries in the world they now add iodine to salt because the World Health Organisation is really worried about the effects of iodine deficiency in women,” Mosley continues. “In the UK we don’t but in other parts of the world it’s been incredibly effective. Iodine is one of the things I would bang-on about.”