Friday, August 1, 2014
Yoga & The Digestive System
I have looked at a number of physiological systems in this blog to date, but I have neglected this important system, BUT for good reasons which are explored in this blog. As with many aspects in this rush to understand the effect of yoga, we assume far more than we know and we are often wrong (e.g., and high calorie burn/weight loss and cure for many maladies). It is often a fitness/wellness orientation--a health orientation--which is really not what yoga has been about for most of its few millennia of development. Still, yoga likely has a beneficial impact on the digestive system and needs to be addressed to both acknowledge benefits as well as guard against overreaching beneficial claims [with primary attention to the impact of postural yoga, and--unfortunately--an effusive nod to the impact of the meditative aspects of yoga that are its dominant historical aspect.
A YOGA PRACTICE session may affect the respiratory, cardiovascular, lymphatic, neural, neuro-endocrine, eastern energy [chakra/meridian] systems.
The digestive system—the integumentary system—has not been addressed to date in this blog. This is because a description of a relationship between yoga and digestion is more difficult. It is generally apparent that the body-mind aspects of relaxation and postural work will affect the digestive system and likely in a positive way. However, the impact of nutrition clouds specifics because of the wide variety of nutritional intake and the impossibility (and the undesirability) of controlling nutrition in human beings. There are wide variations in human dietary habits with very specific impacts, such as more or less fiber/”roughage” and the quality of the diet, as well as the impact, for example, of medications and alcohol and dieting. There are variations in metabolism rates. And there are variations in mental states and activity levels.
Given this inability to standardize/control, first, it is important to look at the elements of the digestive system to understand that it is more than oral salivation and stomach and intestinal actions or even “accessory organs” such a the liver, gall bladder and pancreas.
Digestion is complex, and “intelligent,” without thinking/autonomic. There is the breakdown of food into complex chemicals. And then, there is the transfer of nutrient to the trillions of cells in the body [10-31+ trillion] that involves systems not typically described as being an aspect of the digestive system. Further, there is the daily death of perhaps 60 billion cells and their protein that need to processed/”digested,” and the role of the vascular and lymphatic systems in this regard. And finally, there are ten times more bacteria than body cells [100+ trillion, not to mention viruses, fungi, and protozoa] inhabiting the body and proportionally largely in the digestive system that are essential, but not the body per se. And all of this is just a thin sketch of the system.
Digestion of proteins in the stomach and intestines
What We Might Say About Yoga & Digestion
Before Beginning Practice:
While there are specific suggestions with regard to the impact of liquid and solid intake prior to a practice session, there are no universal guidelines regarding delay or no delay, volume, and specific substances.
It is possible to come to a practice session with pre- and post-efforts to affect the digestive system. Traditionally, Ayurvedic practices and yoga have been described, noting differences in a person’s overall body/mind type and diets related to each type. In high sport performance, there are a variety of substances that might ingested as various points, and something like this may come into some types of yoga practice across time. Further, there is interest in probiotics, fermented and raw food, mineral and enzyme supplements, vegan diets, colonics, etc.
The habitual dietary practices that precede and then follow the session will have a more profound impact on the yoga practice than the specific style of practice itself. However, repeated yoga practice may begin to alter/transform dietary practices [perhaps as attention to the body makes the practitioner more aware of the impact of diet on practice].
The General Impact Of Practice Itself Upon The Digestive System:
The emotional state of the practitioner and the amount of energy that one brings to a specific session will have an impact in what is going to physiologically occur in that session. Anyone who practices frequently will note variations in flexibility and energy even day-to-day. And so, if a practice that felt “good” one time and then “harsh” on another time, there will be a different internal process no matter what the style of the practice is.
Further, the emotional style of the practice will have an effect. A practice that quiets and stills may have a different impact than a very active practice. Generally, stillness may trigger a parasympathetic response while high active practice, a sympathetic nervous system response. Stillness/slowness/holding is likely to optimize holistic monitoring of systems to bring them into balance, while intense activity is likely to optimize core survival functions to optimize these responses and improve performance. Digestive processes do get more “pumped” in high activity and may emphasize different processes, such as more “lactic burn” in muscles that impact differently on waste processing.
Poses such as child, a kneeling twist, cat/cow, on back with one or both knees to chest, and on back folded leg twists to side have been suggested as specific interventions. Varieties of pranayama or breath work and abdominal muscular movement can massage the central body. A comprehensive sequence of postural yoga including inversions will have some impact. However, due to the inability to control so many factors of human behavior, what that impact will be will likely rely on participant self-reports of either improvement or no change.
What Western Research Offers Regarding Yoga & Digestion
Cutting to the chase: Not much. There is a vast about of research on digestion and clinical intervention with digestive disorders, but an absence of specific medical/physiological yoga/digestion research studies. I was hoping to find some reliable information, and it is likely that there is research on this topic that I have missed. However, when some thought is given to this topic, it becomes apparent that it is difficult to control variables, especially diet, to assess the impact of postural work.
Yoga web/blog sites have no problem suggesting yoga solutions for digestion. Support for solutions are more intuitive feelings and personal experience. Conclusions tend to be anecdotal evidence: involving primarily participant self-reports. This type of evidence is typical for many body-mind studies that aspire to measure the effectiveness, for example, of yoga/taichi/reiki and cancer. And several of these studies have been funded by national health organizations and regional medical facilities. Further, the studies are small (and like will be due to lack of funding due to no real financial incentive for large studies as, for example, with pharmaceutical research. Benefits reported tend to be participants’ reports of feeling better, sleeping better, having less pain, more balance, etc. And it might be expected that staying with a process over a number of interventions will likely result in reporting better experiences [Otherwise, why continue?]. Studies of body-mind practices such as yoga have done good work on other physiological effects where they can use evidence of brain activity and fluid chemistry. Measuring specific effect of postural work or breath on digestion would be difficult. Again, a person’s dietary habits which vary widely as well as level of health and daily activity patterns and general attitude and metabolic rates and even dietary style.
Yoga likely has a generally positive effect on digestion and may have a profound effect, and it doesn’t appear to have negative effects for most individuals. However, reliability and validation of specific poses and specific diets remains in the realm of belief or anecdotal evidence more than fact.
Gentle yoga can be soothing in a way that is known to alter body physiology toward stress reduction. And simply as a fitness process, more intensive postural yoga can be functionally stressful in exercising the body. A yoga practice session tends to involve a sequence of postural work that involves a comprehensive stretch of much of the body, and this occurs throughout the practice rather than something done briefly at the beginning and/or end of exercise. And yoga typically has a variety of inversions and twists and squeezing compressions of the central body [somewhat akin to massage and acupressure but typically more generalized] that are distinct from other forms of exercise.
Further, beyond exercise, there is a relaxation component that is important in yoga practice that soothes and calms and quiet, and that offers the experience of “release” even in a very active practice.
It is often suggested and likely very possible that yoga practice itself can, across time, modify dietary habits of some participants, both by developing body awareness and by intentional association with a more optimal general or specific strategy such as Ayurveda.