1 Introduction

Approximately half of the global burden of cancer cases

occur in Asian countries. It has been projected that ~10.6 million

cancer cases may occur in 2030 (Sankaranarayanan et al., 2014).

The incidence of cancer will increase due to urbanization, lifestyle

changes (unhealthy lifestyle such as use of tobacco, alcohol

consumption, and unhealthy diet), aging (one of the key factors

of cancer), and socioeconomic development. The incidence and

mortality rate of the ten most common cancers (the cancer types

include lung, stomach, liver, colorectum, oesophagus, prostate,

bladder, leukaemia, lip and oral cavity, and non-Hodgkin

lymphoma in men; the cancer types include breast, cervix uteri,

lung, stomach, colorectum, liver, corpus uteri, oesophagus,

ovary, and leukaemia in women) will increase by the year 2030

(Sankaranarayanan et al., 2014).

Diet is one of the influential environmental factors associated

with cancer risk. A proper dietary pattern may reduce the risk

of cancer development (Vera-Ramirez et al., 2012); importantly,

diet plays a critical role in breast cancer risk (Ewertz & Gill, 1990;

Sieri et al., 2008). The American Cancer Society proposed some

nutritional guidelines (categorized as diet, physical activities, and

weight management) for cancer prevention based on scientific

evidence; the recommendations are also updated based on the

recent scientific reports (Bail et al., 2016).

2.2 In vivo studies

Kefir is a probiotic fermented milk product with several

health benefits. Melo et al. (2018) studied the health beneficial

effect of fermented kefir milk on azoxymethane (AOM)-induced

ACF in BALB-c mice. The supplementation of 5 ml/kg of kefir

for 8 weeks significantly suppressed the formation and size of

AOM-induced ACF in BALB-c mice. The bioactivity of kefir

greatly depends on its microbial composition, especially the

presence of probiotic strains. Ultra-high temperature treated

kefir milk enhanced the growth of L. acidophilus more compared

with pasteurized kefir milk. The study suggested that ultra-high

temperature treated kefir milk enhanced the growth of probiotic

strains, and regular consumption of kefir could prevent the

occurrence of colon cancer (Melo et al., 2018). The fermentation

conditions, especially fermentation period, significantly influenced

the anti-proliferative effect of kefir (Hatmal et al., 2018).

2.3 Results of human studies

Demidov et al. (2008) conducted a randomized, open-label,

pilot, phase II clinical trial and revealed that supplementation of

Avemar™ (fermented wheat germ extract) during dacarbazine-based

adjuvant chemotherapy improved the overall health status and

reduced the mortality rate of high risk stage III skin melanoma

patients. The mortality of the patients was 34.6% in the Avemar™ supplemented group, which was significantly lower compared

with that of the control group (61.5%). The experimental group

showed a reduction in disease progress and improvement in overall

health status. The study recommended that Avemar™ could be

included in adjuvant melanoma therapy (Demidov et al., 2008).

A case-control study was conducted by Sonoda et al. (2004) in

Japan based on the relation between the diet and prostate cancer

and suggested that the consumption of fermented soy product and

fish greatly reduced the risk of development of prostate cancer.

Consumption of vegetables, fruits and milk are not associated

with cancer incidence (Sonoda et al., 2004). Similarly, another

case-control study showed that the consumption of miso soup and

other soya foods reduced the risk of occurrence of hepatocellular

carcinoma in Japanese A-bomb survivors (Sharp et al., 2005).

Recently, Barrubés et al. (2018) reported that high consumption

of dairy products and low-fat milk is associated with a reduced

risk of development of colorectal cancer in older Mediterranean

individuals (Barrubés et al., 2018).

3 Conclusion

Acknowledgements

We wish to thank Faculty of Pharmacy, Chiang Mai

University, Chiang Mai, Thailand for the support. P.K. and B.S.S

acknowledge the Chiang Mai University-Post-doc grant for the

necessary support.