The differences in physiological signals induced by warm/hot and cool/cold food ingredients in healthy people with hot and cold constitutions

In the traditional Chinese medicine (TCM), both of personal constitution and food attribute could be divided into hot and cold categories. The dietary therapy claims that people need to select foods with attributes opposite to their constitutions in order to maintain the human vitality. However, there are less scientific evidences about the clear definition of connection between food attributes and personal constitutions. Therefore, establishing a suitable methodology to define the scientific attributes for food ingredients is a very important issue for the Chinese medicine dietary therapy.
The first study was to investigate the relationship between the different food attributes and the physiological signals produced in the healthy subjects with different constitutions. Hopefully, a suitably scientific methodology for defining food attributes would be established. This work selected the well-recognized aged ginger tea (AGT) and coconut water (CW) to be warm/hot and cool/cold samples. Physiological signals were then monitored with the modernized Chinese medicine diagnostic instrument: novel noninvasive sphygmography; and the Western medicine diagnostic instruments: the skin and axillary temperature sensors, the heart rate variability, a laser Doppler anemometer (capillaroscope), and a blood pressure monitor. Besides, the questionnaire about subjective feeling would be used to evaluate the feelings of subjects after drinking samples. The personal constitutions of 30 subjects would be diagnosed by Chinese medical doctors using the division of personal constitution questionnaire, asked record, and tongue image.
As the baseline faster heart rate, as well as smaller h1 (height of percussion wave), h5 (height of dicrotic wave) and area under the sphygmogram of the hot constitution subjects (n = 19), this work suggest the blood vessel of these subjects may be tighter than that of the cold constitution ones (n = 11). Stroke volume increased and pulse pressure decreased in the cold constitution subjects after taking the warm/hot food, AGT, which may elevate arterial compliance corresponding to maintaining an estimated radial-arterial diameter in our study. However, the percussion wave widened and h4 (height of valley) increased in the hot constitution subjects after taking AGT. This corresponds to the markedly reduced radial-arterial diameter, indicating tighter blood vessels than the baseline status. In contrast, the cool/cold food, CW maintained the radial-arterial diameter of the hot constitution subjects. This result confirms that selecting foods with attributes opposite to personal constitutions is actually important. Moreover, novel noninvasive sphygmography may be a useful instrument to classify scientifically the hot personal constitution and the responses to different food attributes.
The capillary red blood cell (RBC) velocity of nail fold microcirculation (NFM) of the hot constitution subjects was accelerated significantly after drinking the warm/hot-attribute AGT, which may be the result of elevated vagal activity (nHF and HF) leading to arteriole dilation in these subjects. In contrast, in the cold constitution subjects, capillary RBC velocity decelerated significantly and skin temperature decreased markedly after drinking the cool/cold-attribute CW, which may have been induced by sympathetic nerve activation causing the arteriole to be constricted. Accordingly, the use of capillary RBC velocity of NFM measured by laser Doppler anemometer may be a promising way to classify the attributes of food ingredients in accordance with different personal constitutions.
The second study was to investigate the relationship between the different food attributes and the capillary signals of NFM produced in the healthy subjects with different constitutions. This research expected to confirm that the measurement of NFM is a suitable methodology to scientifically define the food attributes. This work selected watermelon (W) and cantaloupe (C) to be the cool/cold samples, as well as fried peanut (FP) and seedless dried longan (SDL) to be the warm/hot ones. Physiological signals were then monitored with a laser Doppler anemometer and the sensors of skin and auricular temperature. Besides, the questionnaire about subjective feeling would be used to evaluate the feelings of subjects after taking samples. The personal constitutions of 50 subjects would be diagnosed by Chinese medical doctors using the questionnaire pertaining to the division of personal constitution.
As the results of the subjects with any of the constitutions, the warm/hot-attribute FP and SDL significantly increased the capillary density, diameter, and RBC velocity, while the cool/cold-attribute W and C markedly decreased these capillary signals. However, the capillary density and RBC velocity of the hot constitution subjects (n = 29) after taking SDL was raised more significantly compared with taking FP, but no differences between taking W and C. In contrast, the capillary density and RBC velocity of the cold constitution subjects (n = 21) after taking C was reduced more significantly compared with taking W. Accordingly, the capillary RBC velocity and other capillary signals of NFM should be a suitable method to scientifically classify the food attributes in accordance with the different constitutions of people.
Furthermore, this study calculated the sensitivities of capillary density and RBC velocity of the subjects to the same attribute of samples. The error-count estimate of discriminability on the personal constitution derived from these sensitivities was less than 15%, which was compared with the constitutions diagnosed by Chinese medical doctors. Therefore, this work also suggested that the diagnosis of personal constitutions in the Chinese medicine was quite objective and reliable. Besides, these capillary signals in NFM may help us to figure out personal constitutions in the future based on more database of the responses to different food attributes in the human body.