Modulation of immune function and changes in intestinal flora by Brassica rapa L. (Nozawana)

Dietary foods have functions that can prevent disease and improve immune function, eg. increasing resistance to infection and preventing allergies. Brassica rapa L., known as Nozawana in Japan, is a cruciferous plant and a traditional vegetable of the Shinshu area. Nozawana leaves and stalks are processed mainly into pickled products called Nozawana-zuke. However, it is unclear whether Nozawana exerts beneficial effects on immune function. In this review, we discuss the evidence we have accumulated, which indicate Nozawana has effects on immunomodulation and gut microbiota. We have shown that Nozawana exerts an immunostimulatory effect by enhancing interferon-gamma production and natural killer activity. During the fermentation of Nozawana, the number of lactic acid bacteria increases and cytokine production by spleen cells is enhanced. Moreover, the consumption of Nozawana pickle was shown to modulate gut microbiota and improve the intestinal environment. Thus, Nozawana could be a promising food for improving human health.