In the Home: This is where 药食同源 is most alive. A parent might add goji berries (枸杞, gǒuqǐ) to porridge for eye health, brew a pear and rock sugar soup for a dry cough, or make a chicken soup with astragalus root (黄芪, huángqí) to boost immunity. These aren't seen as exotic recipes but as common sense care.
In Restaurants and Commerce: Many restaurants, especially in Southern China, are famous for their slow-cooked soups (老火汤, lǎohuǒtāng) which are formulated based on 药食同源 principles for different seasons and health benefits. You'll also see the term used heavily in the marketing of health foods, herbal teas, and nutritional supplements.
Formality: The term itself, 药食同源, is somewhat formal and philosophical. In casual conversation, people are more likely to talk about the specific action, e.g., “This is good for your throat” (这个对嗓子好, zhège duì sǎngzi hǎo) rather than stating the abstract principle. However, the underlying philosophy is universally understood.