Book Release – Ṛtu Vidyā: Ancient Science behind Menstrual Practices, by Sinu Joseph

Ṛtu (pronounced as ruthu) is one of the words in Sanskrit for menstruation. Ṛtu also means season. Vidyā means knowledge. Ṛtu Vidyā is the coming together of various Indian knowledge systems that provide information about the science of menstruation which is relevant even to this day.

To participate in a discussion on this subject, register for the Digital Launch (Oct 17th, 8.30 PM IST), by clicking on this link –

Here is an introduction to the book Ṛtu Vidyā by Sinu Joseph


Every once in a while, I receive a request from menstrual researchers and activists asking me to pinpoint them to ancient texts which explain why Indian women follow certain practices such as avoiding specific types of food, cooking, touching others or entering Hindu temples during menstruation. How I wish such information readily existed, as it would have spared me the difficult task of penning this book!

India’s ancient texts have long lists of to-dos and not-to-dos prescribed for menstruating women, but rarely do they explain the reason behind this menstrual regime. That information is sacred and not revealed easily. To the one with faith, the questions never arise. To the one without faith, the answers must be earned, often through long and arduous journeys, both within and without. 

The last five years of my decade long work on menstruation has been spent on a journey traversing India and delving deep into India’s indigenous sciences to piece together the varied information available on this topic. Although I read and re-read ancient texts and documents pertaining to this subject, my real understanding began only when I met and interacted with wise men and women from India. And most of all, when I myself experienced how cultural practices around menstruation, often dismissed as menstrual taboos, can help to prevent menstrual disorders.

There is a reason why such a book to decode the multitude of cultural practices around menstruation in India, through a scientific lens, has not happened before. Firstly, India’s traditional knowledge systems which form the basis of these practices, have been sidelined as ‘alternate systems’ and the subtle sciences that they represent has not been fully acknowledged in the modern scientific community. Secondly, to fully grasp even the simplest cultural practice, there is a need to study diverse topics from Āyurved to Āgama Śāstra, all of which would be unfamiliar to those who have only dealt with western sciences. And thirdly, unless this knowledge is clubbed with the experience of menstruation itself, the chances of erroneously interpreting cultural practices are high, as we see in articles and books on menstruation authored by male writers, regardless of good intention. There are of course, exceptions to the rule. In the course of my own study, some of my greatest teachers have been men who, in their own lives, have gone beyond stereotypical definitions of gender and have been able to experience the feminine in profound ways.

In the chapters of this book, readers will find answers to many of the cultural practices around menstruation that are currently followed by women in India.

The book is divided into two parts. In the first part of this book, each chapter delves into a different cultural practice such as, the celebration of menarche, the menstrual regime prescribed in ancient Āyurved texts, menstrual seclusion practices, and the notion of menstrual impurity. There is an exclusive chapter for sportswomen to understand their body through Āyurved given that there is so little information for women in the menstrual age to go along with the natural rhythm of their menstrual cycle and yet be able to perform well in a physically demanding career. In addition to these, there are some interesting facts about menstruation that have rarely, if at all, been spoken or written till date, such as the celestial influence on the female menstrual cycle and how women’s cycles can be predicted through certain sciences. Part 1 of the book ends with the idea of why the menstrual cycle, as understood in ancient India, is a gift to womenkind and how it gives women an opportunity to tap into their unique cyclic patterns for enhanced productivity in work and life in general.

But, this book is not just about decoding the science behind cultural practices around menstruation. It is also about inculcating a holistic understanding of menstruation as envisaged in the ancient texts of the Hindus. What did our ancestors know about menstruation that made them at once revere and fear menstruating women? The answer to this question is covered in the chapters of the second part of this book, where we delve into menstrual practices with respect to religion and spirituality. Many have questioned the seeming contradiction of menstruating women being restricted from entering Hindu temples or reciting certain mantras on the one hand, and on the other hand celebrating the menstruation of Devī in temples like Kāmākhya. An attempt has been made to reconcile this seemingly contradictory perspective in the second part of this book. The testimony and real experiences of women who have broken the rule and visited temples during menstruation is among the most important additions to this work. There is also a chapter that decodes, and if I may say, set right, the well-known Hindu mythology of menstruation being a result of women incurring the sin of Indrā’s crime of killing a brāhmaṇa. The second part of the book ends with a chapter that gives a peek into menstrual practices in Christianity and Islam, while explaining the absence of such practices in the Sikh religion.

As part of writing this book, I have enjoyed the study of various indigenous knowledge systems including the Ṣaḍ-Darśana, Āyurved, Tantra, Cakra, Yōg, Āgama Śāstra, Jyotiṣa Śāstra and several sub-texts from these categories. Wherever possible, explanations from modern science and research has been studied and added to make it familiar and easier for readers to comprehend. The reason for studying such diverse topics was to understand the fundamental principles governing the idea behind the instructions in these texts, to go back to the basics of what these texts are meant to reveal, and to understand how the practices prescribed impact the human system, especially with respect to women’s health. This exercise has made me realize that in order to understand menstrual practices, it is a must to know the governing principles of multiple indigenous sciences, because they are interconnected. Even to dismiss these practices as superstition or taboo, one needs to spend at least a few years learning the various sciences, from the knowledge of which, such practices emerged. With so much ‘homework’ required, it is not difficult to imagine why there is a greater tendency to dismiss these practices as superstition or religious taboo, especially by those who are unfamiliar with Indian science, philosophy and culture.

Having said that, this book would not have been complete with only a secondary study of the sciences and without the actual physical experience, and in the process gathering longitudinal evidence from many women, of how cultural practices prescribed during menstruation impact menstrual health. Just as modern scientific experiments create suitable ‘lab conditions’ to be able to test the hypothesis without external interference, in the case of experiencing the impact of menstrual practices too, such conditions need to be met internally. Therefore, I worked to bring my physical body to a state of good health, in order to rule out disturbances in the menstrual cycle owing to existing health issues. It was also important to bring the body and mind to a stable state through practices of yōg, prāṇāyāma and meditation, so that I could experience subtle changes during menstruation – this lies at the core of directly experiencing the effect of cultural practices during menstruation.

This book is also the result of rigorous ground work over a period of ten years with my team, which included interactions with thousands of adolescent girls and women across the Indian states of Karnataka, Tamil Nadu, Andhra Pradesh, Kerala, Jharkhand, Bihar, Assam, Nagaland, Manipur and Mizoram to get a first-hand perspective of cultural practices around menstruation which are followed to this day. Therefore, the practices chosen to be explained in this book have been arrived upon based on the current relevance and importance to Indian women.

To understand the impact of Hindu temples on menstrual cycles, temples such as the Bhagavathi temple in Chengannur (Kerala), the Valliyamkavu Devī temple in Mundakkayam (Kerala), Umānanda temple and Kāmākhya temple in Guwahati (Assam), and five Sastha temples associated with Sabarimala in Tamil Nadu and Kerala were visited and part of the study. Details pertaining to the restrictions on entry of women in the menstrual age in Sabarimala was initially part of this work, but was later published as a separate book titled “Women and Sabarimala: The Science behind Restrictions”, which was released in November 2019.

There has been a time in India, where one did not have to explain rituals or religious practices. Our ancestors had a strong sense of unshakable devotion (bhakti), to not need a scientific explanation. This led them to have experiences which had the same effect as a scientific understanding. So it was not uncommon that every time I interacted with genuinely religious people, in search of scientific answers, their question to me would always be ‘but why do you want to know all that…just have bhakti.’ So why do we need to know all this through a scientific lens?

The influence of menstrual activists, both within and outside the country, who are unfamiliar with local traditions and culture, has done more harm than good. Their interference has, at times, resulted in governments making policies to enforce a change in traditional menstrual practices. A case in point is the government of Nepal introducing a law that criminalizes menstrual seclusion practices called chaupadi. While the law was unable to enforce an end to the practice, it did make practitioners go underground, further risking the safety of menstruating women. Another example is the case of the Sabarimala temple in Kerala that was forced by the Supreme court of India in 2018 to remove its restriction on entry of women in menstruating age, following a petition backed by activists, leading to a massive uproar among devotees, both men and women. At times, westerners have seen in menstruation a great opportunity for fame, often obtained by belittling cultural practices that are different from their own. An example is that of the documentary “Period. End of Sentence” which shockingly won an Oscar award in 2019 for showcasing India as a country of people who disrespect menstruation and are blinded by menstrual taboos. With absolutely no knowledge of the culture they seek to condemn, and no effort to learn about native knowledge systems, such people somehow assume the authority to impose their limited thinking on the rest. Thus far, the voices commonly heard are of those who are backed by large organizations putting them on popular platforms to create a socially engineered narrative. This needs to change.

During the course of my study, I came across many women who never once felt that the cultural practices around menstruation have a negative connotation, and chose to follow these practices with joy. I feel privileged to have learnt from these wise women and their experiences. In some of the chapters in this book, you will find their version of the story.

Who is this book for?

This book is foremost for those women of India, who have questioned the cultural practices around menstruation, at times being genuinely curious, and at times, by being rebellious.

This book is also for those who have difficulty in coming to terms with menstruation as a positive occurrence and assume that India has a cultural stigma around the subject.  

This book is for the activist who is on a mission to ‘empower’ the women of India by asking her to forsake the cultural practices around menstruation.

This book is for the men, who in spite of good intentions, often speak on women’s behalf without a clue about our body and our menstrual experience.

This book is for menstrual researchers, who will find several unexplored areas of research on menstrual health that can change the way we perceive menstruation.

This book is for the decision-makers who feel pressurized to go with the popular voice, and lack the time and resources for detailed study on such a subject.

Most readers will agree that books about women, written by women, through a feminine (not feminist) perspective, are rare. That such a work will answer many, if not all, of the readers’ questions on this subject, is my sincere hope. That this book will encourage readers, especially women across the globe, to start their own journey of learning, surpassing, and wherever necessary, correcting, what is presented here, through the lens of the native science of their motherland, is my deep desire. That, through this book, a fresh and meaningful scientific narrative on menstruation will emerge that is not limited to western scientific perspectives, will be a purpose met.

The book is currently listed on the following platforms

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EBook versions on Kindle, Google Books, Kobo will be available in a few days.

You can contact the author at



  1. Please make the book available on google play book as I’m living in a country that makes amazon shipping difficult and long ! Looking forward to it 😉

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