The brilliant boy with so much radiance who protected his mother and burnt the demon at the time of his birth is Sage Chyavanar. He is one of the most respected sages in the Bhrigu clan and his name in the pravara is mentioned as Chyaavana.
It is told that he does Tapas for years together, which includes 12 years of Tapas under water at Prayag (at the junction of Ganga, Yamuna and Saraswati) and also some instances where termites build castles around him since he meditates unmoved in one place. He is also described as extremely skinny and looks very old, impatient, obstinate, quick to anger.
In one instance in a Yagna he invited "Ashwini Devas" for the Soma bana drink. Each Yagna is done with specific invitees and the offering in Yagna is given to only those invitees. Typically only Devas are invited and though technically being devas, "Ashwini Devas" are the lord of medicine to the mankind. Since Devas are immortal they do not require any medicine so they considered "Ashwini Devas" as inferior to them. The other reason why devas were against Ashwini brothers is interesting, "They kill plants and herbs to make medicines, though medicines save human life, they still kill the plants and hence they are not qualified in this divine gathering". Now this highlights that killing even a plant despite it saving lives are considered bad in certain section of the universe. Compare the type of crime we commit when we kill animals to satisfy our taste buds.
The devas objected to Sage Chyavanar that he cannot call Ashwini Devas for the yagna and offer them Soma Bana as it the right of "qualified" devas only. But the sage was obstinate and told them that it is his Yagna and he shall decide whom to invite and what to offer. Considering the spiritual powers of the Sage, the devas grudgingly agreed.
Ashwini Devas were treated well in the yagna by Chyavanar and were offered Soma bana drink. In return Ashwini Devas gave Sage Chyavanar a special medicine which shall remove his old age and bring back youth and virility to him.
This potion / medicine which was given to Sage Chyavanar by Ashwini Devas is called as Chyavana Prasava Lehyam now popularly called as "Chyavanprash" today.
The above story is documented part of our Vedas which are actually undated, yet it is dated at least 5000 years back even by skeptics. Now if that is so, we have a medical product in Ayurveda, to this date which delivers the same benefits.