Dietary Therapy in Classical Chinese Medicine

by Dr Simone Ormsby

BSc (Syd. Uni. Hons Molecular Biology & Genetics); BHSc (UTS TCM); PhD by Higher Research (WSU).

The traditional medicine system of ancient China utilised multiple strategies to maintain harmony and prevent illness within the body, but also for the rectification of disease once symptoms occurred. This system of medicine is still practiced today by degree qualified Chinese Medicine Practitioners and incorporates: herbal remedies, acupressure, acupuncture, auricular (ear acupressure / acupuncture) therapy, moxibustion, ga sha (a type of massage using a specific tool), tui na (massage using knowledge of the meridian system), cupping, tai chi, qi gong, and dietary and lifestyle advice.

A foundational premise that underlies all of the theoretical frameworks of Classical Chinese Medicine is Yin and Yang theory. The first discussions of Yin and Yang theory date back to Lao Tzu's Tao Te Ching The Book of Changes written about 2500 years ago (Lin, 2006). Yin and yang theory specifies that all of nature can be divided into two main opposing categories. Some examples are provided below.

Yin

Dark

Night

Winter

Cold

Rest

Female

Physical Form eg flesh

Watermelon

Yang

Light

Day

Summer

Sun

Hot

Activity

Male

Bodily Process eg digestion

Pepper

Yin and Yang theory as you can see can also be applied to the body in terms of maintaining health, for example eating seasonally, that is cooler foods in summer and warmer foods in winter, but also for the rectification of illness, for example, the temporary use of cool foods for say heartburn, and warm foods for frostbite. We have to be careful however not to overly consume too much of a particular temperature, especially at the wrong time of year. For example, celery is classified as ‘cool’ (Leggett, 1995) so overconsumption of it will make a person who is too cool, e.g. someone with hypothyroidism, colder. This would be worse if it is also winter. A hotter constitution person however, such as a male, will take a longer time period to be cooled by celery.

To make it more complicated, as digestive enzymes operate best at the body temperature (37 degrees), we should mostly consume neutral temperature (balanced yin/yang) and warm and cooked foods, so as not to strained the digestive processes. Iced foods are absolutely not recommended, even in summer, as they will result in the digestive processes being slowed. This can lead to cold accumulation, one symptom of which is fluid retention.

In 2021 I published a book chapter “Hot and Cold Theory: Evidence in Nutrition” in Hot and Cold Theory: The Path Towards Personalized Medicine (Ormsby, 2021 - Maryam Yavari Editor) - https://link.springer.com/chapter/10.1007/978-3-030-80983-6_6 that explains this theory in more detail. So rather than reinvent the wheel, some excerpts are inserted below and subject to conditions of copyright:

“As an overall broad classification, with the exception of spices, foods of plant origin are predominantly considered to be more ‘cooling’ (Zhou et al., 2012, Anderson, 1980, Lee and Shen, 2008, Huang and Wu, 2002). In contrast, most meats, animal protein, oils and alcohol, are generally thought to be more ‘warming’ (Anderson, 1980, Flaws, 1998, Leggett, 1995, Lee and Shen, 2008, Manderson, 1981) (see table 6.1). A greater proportion of fruits and vegetables are also typically classified as ‘cool’ rather than ‘warm,’ which likely reflects the greater variety available in the warmer months. Several authors also suggest some other rules may apply. For instance, that more brightly coloured fruits that are sweeter and not especially juicy such as litchi (lychee), longan, and durian may be more ‘heating’ (Xu, 2019, Han et al., 2020, Zhou et al., 2012, Anderson, 1980, Huang and Wu, 2002); whereas those that are less brightly coloured, and juicier (with higher fluid content equating to more ‘cooling’), are potentially ‘colder’ in nature (Anderson, 1980, Wandel et al., 1984, Leggett, 1995). Likewise, plants that are pale or darker in colour (white, grey, green, blue, purple); quicker to grow; grown in winter, water, moist environments or closer to the ground (and thus more able to absorb water); as well as having less access to sunlight, maybe relatively ‘cooler’ than those that are more vibrantly coloured (red, orange, yellow); slower to grow; having greater access to the sun; grown in summer, on land, and drier locations; and needing more warmth to ripen (such as red fruits) (Xu, 2019, Lee and Shen, 2008, Leggett, 1995, Han et al., 2020, Anderson, 1980, Zhou et al., 2012). According to TCM theory, spicy and sweet foods are considered to be more ‘heating/yang’ than the bitter and sour flavours (‘colder/yin’) (Xu, 2019, Han et al., 2020). Interestingly, Leggett (1995) also suggests that foods artificially forced to grow quickly are more ‘cooling’ than those that are naturally grown, and in addition that some chemicals added to foods may cause ‘heating’ reactions”.

How food is prepared is additionally considered to alter intrinsic temperature properties (Currier, 1966, Zhou et al., 2012, Anderson, 1980, Payyappallimana and Venkatasubramanian, 2016). Longer and slower cooking for example, is believed to yield more ‘heating’ effects (McCracken, 2012, Leggett, 1995); as does the addition of certain ingredients during the cooking process, such as alcohol (McCracken, 2012), ‘heating’ oils (Zhou et al., 2012, McCracken, 2012), and many spices (Dua and Dua, 2011, Guha, 2006, McCracken, 2012, Currier, 1966, Aghili, 2008). Other cooking methods also stated to be ‘warming’ include grilling, roasting, barbecuing, stewing, smoking, and long-simmering (McCracken, 2012, Leggett, 1995). With respect to more balanced cooking methods, steaming is thought to be predominantly neutral, and sun-drying only marginally heating (Anderson, 1980), whereas long slow-boiling is considered relatively more ‘cooling’, and cold-infusion, the coldest method.

Further coding of food as ‘heating’ or ‘cooling’ is determined by observation of the resultant physiological effects after consumption (Anderson, 1980, Wandel et al., 1984), or ‘virya’ in the Ayurvedic system (Balasubramanian, 2015). Indeed, in humoral medicine, these impacts are the major determinants in food nature or body temperament classification (Aghili, 2008, Ibn-Sina, 1998); however, in addition to ‘heating’ or ‘cooling’ properties, foods are also considered to a lesser extent, in regard to moistening and drying effects (Avicenna, 2005). Overall therefore, foods may be classifiable as hot and dry; hot and moist; cold and dry; or cold and moist, with hot and dry considered to be the most heating (Ardekani et al., 2011). Anderson (1980) for example, classified ‘heating’ foods like chilies as irritants due to causing ‘hot’ symptoms, such as burning, and rubefacient (redness); as well as carminative (flatulence releasing) effects. Dried and scratchy foods like curry and coffee were also placed in this category, as a consequence of the mouth/throat dryness or soreness that may arise. Furthermore, hangovers and indigestion were suggested to be byproducts of the excessive consumption of ‘heating’ alcohol and fats.

Directions of energy movement are also linked with temperature effects in TCM. For instance, ‘cooling’ foods are said to cool the upper and outer parts of the body first, direct energy inwards and downwards and slow the body down, whereas those that are ‘warming,’ warm from the inside to the outside, move energy upwards and outwards and speed the body up. Very hot foods such as chillies provide a mixed effect, by initially producing intense internal heat, followed by cooling via the induction of sweating (Leggett, 1995).

There are nonetheless regional variations and exceptions to these generalizations (Logan, 1977, Currier, 1966, Anderson, 1980), as well as notable differences amongst TM systems. For example, Brussels sprouts being green in colour would be assumed to be ‘cold’ however according to TCM, are ‘warming’ in nature (Leggett, 1995). Similarly, bitter taste in TCM is associated with ‘cooling’ properties, yet in the HMS, it is considered ‘heating’ (Aghili, 2008). Likewise, in TCM, both Leggett (1995) and Flaws (1998) code eggplant (aubergine) as ‘cooling’, however Han et al. (2020) classifies this vegetable as ‘warming/heating’; and in the HMS, it is also considered ‘heating’ (Aghili, 2008). Wandel et al. (1983) also observed within Southern Sri Lankan communities, that while the labelling of ‘heating,’ ‘cooling’ and ‘neutral’ foods was relatively consistent, the degrees to which foods were ‘heating’ or ‘cooling’ was the subject of much disagreement. Nuances within coding may in part explain some of these discrepancies; for example, river fish in Ayurveda is regarded as ‘cooling’ (Patel, 2010) due to being obtained from aqueous environments, however those that are salty (Patel, 2010), stronger in flavour or stained with blood, are considered more ‘heating’ than those blander in taste (Wandel et al., 1984).

Similarly, according to Lee and Shen (2008), other Indian classifications place fish in the ‘heating’ category on account of it being a meat. Furthermore, the raw versus prepared/cooked state may explain some differences, such as fresh cow’s milk being considered ‘cooling’ in Ayurveda, however ‘heating’ after drying (Wandel et al., 1984). It is possible that some intra- and inter-cultural variability may also be explained by genotype variants amongst plants (Logan, 1977, Aghili, 2008), as well as the seasons, climate, and environments in which the food is grown (Aghili, 2008, Leggett, 1995). For example, food grown in the wild may be more potent in effect than those that are domestically cultivated (Leggett, 1995); and also, that soil compositions today may substantially differ from those in which coding first began. An additional possibility is attenuation to the impacts of commonly consumed foods over time, however when first introduced to a new culture, the effect is much stronger (Leggett, 1995). Nonetheless, Anderson (1980) suggested that overall, there was “striking similarity in coding cross-culturally” [p 239], and in addition, that the opinions of the majority should be considered.

As medical symptomologies are also classified according to ‘hot’ or ‘cold’ predominance, diet and food preparation is able to be purposively modified for the maintenance of health, as well as rectification of disease. In this regard, two main principles are applied. Firstly, in the preventative approach, the avoidance of environmental as well as dietary extremes is recommended in order to maintain balance between the opposing forces of ‘hot’ and ‘cold.’ Secondly, for the management of illness, the principle of the ‘selective use of opposites’ is applied in an attempt to rectify imbalances (Logan, 1977).

In the preventative approach, one should not excessively consume ‘cold’ foods, so as to not tip the balance within the body towards the predominance of ‘cold’ and ‘cold’ related disorders (such as cold intolerance, lethargy and fluid retention). The converse also applies to the over consumption of ‘hot’ natured foods (Logan, 1977, Anderson, 1980). Rather, one would aim to consume proportional quantities of ‘hot/warm’ and ‘cold/cooler’ foods (Logan, 1977), as well as those regarded as neutral in nature. As raw food in both the humoral and classical Chinese medical systems is thought to be ‘colder’ in nature than cooked (Anderson, 1980, Lee and Shen, 2008, Leggett, 1995), minimal consumption is also suggested (Guha, 2006). Furthermore, all three medical systems suggest ‘warmer’ natured/cooked foods are easier to digest than raw or ‘colder’ foods (Currier, 1966, Flaws, 1998, Guha, 2006, Chashti, 2004); due to warmth maintaining ‘agni’ or digestive ‘fire,’ as well as the cooking process providing pre-digestive effects (Guha, 2006, Flaws, 1998, Leggett, 1995). Indeed, insufficient warmth for digestion is thought to result in ‘improperly processed’ foods (Flaws, 1998, Guha, 2006, Leggett, 1995, Chashti, 2004), as temperatures are lower than those at which digestion normally occurs (Leggett, 1995), and enzyme functions are therefore, suboptimal (Guha, 2006). Consequently, consumption of refrigerated and/or frozen foods is not recommended (Leggett, 1995, Flaws, 1998).

Additional dietary adaptation based upon knowledge of one’s constitution is also required for longer-term health management. For example, women and the elderly are generally ‘colder’ than men, hence even during the summer months, continued consumption of mostly ‘warmer/cooked’ food, along with minimal intake of fresh seasonal ‘cooling/raw’ produce is recommended. Furthermore, avoidance of foods aggravating to the individual’s ‘dosha’ or constitutional makeup is suggested, that typically also includes factors in addition to temperature, such as, ‘dryness’ for the ‘Pitta’ (fire) constitution (Rastogi, 2014).

More complex considerations of environments are additionally incorporated into dietary recommendations, as external conditions tend to aggravate those that predominate internally. For example, cold, damp weather may compound the incidence of mucous, catarrh, and colds in winter, hence cold, damp foods should be avoided at these times (Dua and Dua, 2011). In addition, one could attentively consume foods opposite in nature, so as to minimize or counterbalance the impact (Lee and Shen, 2008). Such a process naturally occurs to some extent when local seasonal produce is consumed, as ‘cooling’ foods are both more desirable and available in warmer months, and cooked or intrinsically ‘warming’/spiced foods are preferable in winter. According to Wu and Liang (2018), balanced consumption in this way is thought to slow down the ageing process, possibly as a consequence of optimized digestion and nutrition assimilation.

In the secondary approach, nutrition may be utilized for the correction of illness, if for example, consumption of one temperature was in excess, or constitutionally and environmentally considerate ‘cold,’ and ‘hot’ food choices were insufficient to prevent disease (Logan, 1977, Currier, 1966, Anderson, 1980, Kastner, 2004). In these cases, ‘food therapy’ or targeted consumption of foods opposite in nature to the presenting medical symptomologies are applied, while those of the same nature are avoided in order to not worsen the imbalance or condition (Ludman and Newman, 1984, Lee and Shen, 2008, Anderson, 1980, Logan, 1977, Zaman, 2015). One such simple application from TCM is the postnatal consumption of ‘warming foods,’ such as a stew containing chicken, ginger, vinegar and sugar, to counteract the temporary condition of ‘cold’ predominance resulting from childbirth (Anderson, 1980). Another example provided by Logan (1977) from humoral medicine, is the case of ‘‘very cold’ venom from a rattlesnake bite that can be remedied by the intake of ‘hot’ natured foods such as coffee and garlic. Likewise, the study by Mehraban et al (2021) showed that ‘hot’ natured diseases such as gastrointestinal reflux can be treated by ‘cold’ natured plants such as damask rose. Neutral foods can in addition be included so as to buffer or harmonize the ‘heating’ or ‘cooling’ foods being consumed in remedy, as well as supplement blood and strengthen the body’s ability to fight external influences (Anderson, 1980).

Rather than just the simple use of opposites, in TCM additional complexity in treatment is also incorporated after consideration of the nature of the five flavors. For example, “sour food was said to be absorbed by the liver, spicy by the lungs, bitter by the heart, salty by the kidney, sweet by the spleen” [p3] (Wu and Liang, 2018). Thus, in addition to overeating one food temperature, if consumption is “too sour, the liver-qi would increase, and the spleen-qi will decrease. If too salty, it could lead to bone damage, impotent muscle, and depressed heart-qi; if too sweet, the heart-qi would rise up, causing asthma, darkened skin, and imbalance of the kidney-qi; if too bitter, it could cause dryness of the spleen-qi, bloating of stomach; if too spicy, tendons and vessels would become flabby, and vigor would be undermined” [p3] (Wu and Liang, 2018). Indeed, in TCM, temperature aspects are also associated with the different flavors, for example, salt is considered to have a moistening action that is beneficial for dryness; however, in excess, it can result in fluid retention, due to being relatively more ‘cooling’ than ‘warming.’ Bitter taste on the other hand ‘drains and dries,’ hence could be considered comparatively more ‘warming.’ Indulging in one particular flavor therefore, can contribute to constitutional imbalance, as well as organ system disharmony via the route that flavor travels throughout the body (Leggett, 1995).

In Ayurveda, tastes are similarly described as in TCM, except for the addition of the ‘astringent’ category, along with the role they provide in digestive and immune system processes. However, it is additionally suggested that each taste is received on different parts of the tongue, and each of these anatomical locations in turn corresponds to different organs, such as, sweet to the thyroid glands and apices of the lungs (Guha, 2006). Specific tastes are also reportedly derived from differing elemental compositions, and these, along with other qualities, are responsible for the differing physiological impacts (Guha, 2006, Payyappallimana and Venkatasubramanian, 2016). Indeed, food is classified according to the active component or potency, as well as post digestive and pharmacological effects (Guha, 2006, Payyappallimana and Venkatasubramanian, 2016).

Similar teachings are also provided in the HMS, where it is thought that various temperature and moisture combinations in foods specifically target various organ systems, and hence the ability of food to be utilized for medicinal purposes (Nimrouzi and Zare, 2014). Contrasts between the TM systems can nonetheless also be seen, with for example salt being regarded as moistening in TCM, whereas ‘heating’ and drying’ in the HMS (Aghili, 2008).

Additional considerations for the management of illness necessarily also incorporate knowledge of ‘susceptibilities’ (Anderson, 1980) or constitutional differences in TCM, ‘doshas’ in Ayurveda, and temperament/Mizaj types in humoral medicine (Guha, 2006, Ibn-Sina, 1998). For example, men who generally have ‘hotter’ dispositions, would predictably take longer to manifest a ‘cold’ condition from the overconsumption of ‘cooler’ foods or exposure to ‘cold’ environments, than most women, whose constitutional tendency is towards internal ‘cold’. Correspondingly, a ‘hot’ constitution type would also much more quickly manifest a ‘hot’ type illness when excessively consuming ‘heating’ foods or being overexposed to ‘hot’ environments. Another type of ’susceptibility’ relates to poor Stomach/Spleen function in TCM (Leggett, 1995) or weak ‘digestive power’ in Ayurveda (Guha, 2006, Payyappallimana and Venkatasubramanian, 2016), in which one’s ability to process food is compromised. In such a case, TCM recommends a predominance of more easily digested cooked and non-sweetened foods, along with substances that specifically strengthen these functions, such as acrid warm spices like ginger, cardamom, and nutmeg (Flaws, 1998). In Ayurveda convalescent food practices can also be designed to gradually restore ‘agni’ or ‘digestive fire’ (Rastogi, 2014), and likewise, in the HMS, minimally applied spices may be used to aid digestion by increasing food compatibilities, balancing adverse actions and providing nutritional content (Aghili, 2008).

Overall, diets compatible with constitutions, ‘doshas’ and Mizaj types are considered foremost to good health and correct body functioning (Sarkar et al., 2015, Payyappallimana and Venkatasubramanian, 2016); as well as the gradual restoration of health when systems are out of balance (Wandel et al., 1984). Factors in addition to the inherent biological properties of foods (Guha, 2006) being incorporated into diets to combat disease include: the season, freshness, locations and environment in which the food grows (Payyappallimana and Venkatasubramanian, 2016, Guha, 2006, Wu and Liang, 2018); where or how the food is consumed (Guha, 2006, Leggett, 1995); the working or living conditions (Logan, 1977) of the individual; and their gender, age (Guha, 2006, Sarkar et al., 2015, Wu and Liang, 2018), current health (Sarkar et al., 2015, Logan, 1977), illness severity (Logan, 1977), and mental state (Sarkar et al., 2015). Knowledge of these variables provides a unique opportunity to individually tailor diets to not only to correct illness, but also maintain longer term balance. Nonetheless, some illnesses are very complex, and include both ‘hot’ and ‘cold’ aspects (Currier, 1966), such as mental health disturbances with ‘cold’ depression symptoms including lethargy, apathy, and lack of motivation, as well as ‘hot’ anxiety manifestations such as irritability, insomnia and restlessness. Not surprisingly, these conditions can be much more difficult to treat.

Whilst the potency of food is weaker in magnitude than herbs in TCM (Wu and Liang, 2018), longer-term impacts are considered possible due to more frequent consumption over extended periods of time. It was only when this type of rectifying food therapy was insufficient in effect, that Tang Dynasty scholar Sun Simiao stated medicinal herbs should be prescribed for a more powerful effect (Wu and Liang, 2018, Lo and Barrett, 2005).

In this way it was considered that, “…medicine functions by means of food and food reinforces the effects of medicine” [p 1] (Wu and Liang, 2018). A similar concept was developed in humoral medicine, however expanded into a system of grading according to the impacts on the constitution or temperament of the individual, with the higher grades being considered the most medicinal and thus less frequently consumed (Zaman, 2015).

Indeed, Rhazes (865-925) famously stated that “If a physician can treat [a] patient by food, he has been fortunate”, and if this was insufficient “simple drugs” should be used, and in last line “compound drugs” [p 1461] (Zargaran et al., 2014). Specifically, the lowest grade is defined as ‘absolute ailment’ and considered a source of energy, as well as able to be part of the body without changing its functions. The next level, ‘functional food’ provides a greater potential for conversion into energy, as well as the marginal ability to alter the function of the body. It is foods in these first two categories that are predominantly consumed.

The third grade termed ‘pharmaconutrient’ includes those that have medicinal effects able to alter the body’s temperament, that are considered superior to nutritional effects. Only a small proportion of these substances are utilizable for conversion to energy. Fourthly, ‘absolute medicament’ is defined as a drug that affects both structure and function, with little nutritional value. This last type can be poisonous as it has the potency to change the temperament to a maximum effect (Soleymani and Zargaran, 2018, Aghili, 2008). Most spices belong to the third category, with some also belonging to the fourth (Aghili, 2008)”.

The rest of the chapter is a review of scientific investigations exploring the validity of ‘hot’ and ‘cold’ theory and its relationship to nutrition. If interested, the chapter can be purchased using the above pasted link.