https://nutrition.bmj.com/content/early/2021/01/04/bmjnph-2020-000183

Beego, a phonetic articulation in Chinese meaning no eating foods for a period, was originally practiced by Taoists for spiritual purposes in ancient China. It started from the Qin Dynasty (from 221 B.C. to 207 B.C.) and became a popular practice in the Western Han Dynasty (206 B.C. to 24 A.D.), extending to the purposes for both physical and mental fitness. Like Gongfu or martial arts, beego is a part of traditional Chinese culture in fitness. But unlike Gongfu that requires a certain physical talent, beego can be practiced by ordinary people. It consists of two phases, starting with a complete water-only fasting phase for days or weeks, followed by a gradual refeeding phase for the duration of no less than half of the fasting length until normal diet. Psychological induction or mind regulation, including but not limited to meditation, is used to mitigate the feeling of hunger, in particular in the first days of fasting. During meditation, an abdominal breathing method is used to inhale sufficient oxygen and exhale more carbon dioxide.1 2 In addition, light body exercise is incorporated in beego programme to facilitate this practice. In recent two decades with rapid increase of the population in overnutritional condition or with metabolic syndrome, there is also a rapid growing volume of Chinese people participating in beego.

Beego in China has traditionally relied on experience being handed down by word of mouth and features a psychological guidance, yet we are unaware of studies examining the practice; in contrast fasting for therapeutic purposes in the West has been intensively studied since the early 1900s, including modalities like prolonged or acute starvation,3–6 water-only fasting7–10 and various less stringent or incomplete fasting formulas.11 The incomplete fasting formulas appear to be more favoured in Western countries, and include calorie restriction, intermittent fasting, fasting-mimicking diets and periodic short-term water-only fasting with minimal calories or supplements. Contrary to the difficulties in studying complete fasting biology that precludes utilisation of animals (as some animals cannot survive complete fasting for days), studies on incomplete fasting primarily using model rodents has revealed health-promoting physiological responses, and have uncovered underlying mechanisms that can explain these responses. These include but not limited to ketogenesis,12–14 hormone modulation,15–17 reduced inflammation,18 immunological memory,19 promotes regeneration and reduces autoimmunity and multiple sclerosis symptoms20 and fasting confers protection in central nervous system autoimmunity by altering the gut microbiota.21 Fasting also impacts immune cell dynamics and mucosal immune responses,22 and increases stress resistance,23 lipolysis24 and autophagy.25 26 Caloric restriction delays disease onset and mortality in rhesus monkeys.27 28

More encouragingly, clinical investigations in Western countries indicate that fasting reduces obesity3 and hypertension,7 8 improves oxidative stress,29 30 cardiovascular disease,31–33 cancer,34–38 rheumatoid arthritis,39 metabolic syndrome,40 41 osteoarthritis,42 fibromyalgia,43 chronic pain,44 memory,45 circadian clock46 and multiple aspects of life quality.11 47–50

However, the safety and the biological effects of beego, the Chinese traditional fasting practice, remain completely undocumented in scientific format. This study aimed to explore the impact of supervised beego on thrombosis and haemostasis.

Supervised beego improves cardiovascular physiology

Intact blood vessels are instrumental to limiting thrombosis and moderating the capacity of platelets to secure haemostasis.54–56 Therefore, the physiology of vessels is fundamental for supporting haemostasis. Peripheral resistance measures vascular compliance, reflecting friction between the blood and the walls of the blood vessels: both narrower blood vessels and relatively more viscous blood increase peripheral resistance. We observed that the peripheral resistance of beego subjects was maintained in the middle of the normal range during fasting, yet decreased during refeeding, while remaining within the normal range (figure 3A). The reflection coefficient data showed a slow, progressive decrease during fasting, with a further decrease evident after refeeding (figure 3B), results suggesting improved vascular function. The augmentation index is an indicator of peripheral arterial stiffness. This increased within normal range during fasting, but decreased close to the baseline value after refeeding (figure 3C). Pulse wave velocity (PWV) is a measure of aortic arterial stiffness that is a potent predictor of cardiovascular risk; we observed no change in PWV for beego subjects during fasting or refeeding (figure 3D). These data together suggest that vascular-dysfunction-related hypertension risk was reduced in beego subjects by day 7 of refeeding.

P-selectin is a cell adhesion protein that is mainly expressed on the membrane of activated vascular endothelial cells and activated thrombocytes, and the level of P-selectin on activated platelets reflects platelet activation. Our results show that platelet-localised P-selectin levels were significantly reduced during fasting and refeeding (figure 4F). Beego with 14-day fasting and 7-day refeeding displayed similar patterns for the dynamic changes in the above platelet-related parameters (online supplemental figure S4a-f).

To further examine if beego may affect platelet ageing, we measured oxidative stress in platelets. Strikingly, reactive oxygen species levels were significantly reduced during fasting, and this reduction was sustained after refeeding (figure 4G), suggesting that beego confers a significant reduction in platelet oxidative stress. JC-1 assays measure Ψm depolarisation of the mitochondria membrane, and such depolarisation indicates active cell apoptosis and accelerated ageing.59–61 Beego significantly reduced the percentage of JC-1 green fluorescence (figure 4H), suggesting an increase mitochondrial in mitochondrial membrane potential and thus a reduction in intrinsic pathway triggered activation of apoptosis. Consistently, flow cytometry analysis of Annexin V levels revealed a detectable beego-induced reduction in the extent of platelet apoptosis (figure 4I). Thus, our data support the possibility that the observed reduction in platelet count in the normal platelet group may be caused by reduced overall production of platelets, rather than by increased apoptosis or ageing. Beego with 14-day fasting and 7-day refeeding displayed a roughly similar pattern in the dynamic change of these parameters (online supplemental figure S4g-i). These results suggest that in addition to limiting platelet generation (reducing thrombosis risk) without impairing haemostasis capacity, beego may also exert some effect in rejuvenating platelets.

To explore possible mechanisms by which beego reduces circulating platelet count (figure 4A), we examined TPO level produced in the liver. Beego did not result in alteration of the TPO level (figure 4J, online supplemental figure S4j), suggesting that the observed reduction in platelet formation is not caused by regulatory molecules upstream of TPO expression. We therefore performed a proteomics analysis of platelets which revealed that, among the eight proteins essential for platelet formation, G6B and MYL9 were significantly reduced during fasting, and the levels of these two proteins remained low in refeeding (figure 4K, left). These findings indicated that reduction of G6B and MYL9 may be responsible for the observed reduction of platelets, an idea supported further by our heatmap and q value analyses showing obvious and significant reductions in the G6B and MYL9 levels on days wFD7 and rFD7 as compared with wFD1 (figure 4K, middle and right panels).