Today it is a known fact that 80% of the Indian society is vitamin D deficient. It was probably known to our Rishi Munis and they created rituals so that everybody gets enough Vitamin D from sunlight. Shahi snan in sunlight is mentioned in our Vedic literature. • The month of Magha, Vaishakha and Kartik are considered as months for Shahi Snans where one is supposed to worship the sun early in the morning and eat calcium rich food such as Urad Ki Daal or sesame seeds. • Chhat pooja, which falls immediately after Diwali is also linked to sun worship. • Sun is also worshipped in Marghshirsha month, which comes immediately after the month of Kartik. • Kartik purnima and Vaishakh purnima are especially known for sun worship. Vitamin D deficiency has been associated with metabolic syndrome, heart diseases and also with fertility. All these months when sun is worshipped are also the months of increased fertility. After chaturmas is over, Tulsi vivah starts the marriage season during which one worships both Tulsi and Amla. Both of them are known to increase the quantity of semen and increased ovulation. Probably, the age old treatment of infertility was to acquire vitamin D, taking calcium rich food and consume both tulsi and amla on regular basis. The current vitamin D mantra is that 40 days in a year for at least 40 minutes, one should expose 40% of the body to the sunlight either after sunrise or just before sunset. Disclaimer: The views expressed in this write up are entirely my own.