Continuous combined intake of polydextrose and lactitol stimulates cecal fermentation and salivary IgA secretion in rats

Abstract

Immunoglobulin A (IgA), which plays an important role in infection defense, is upregulated in the large intestine and oral cavity through dietary fiber intake. However, the mechanism underlying salivary IgA increase through dietary fiber intake remains unknown. This study investigated timedependent effects of non-absorbable polydextrose (PDX) and lactitol intake on salivary IgA secretion and cecal fermentation. Five-week-old rats were fed a fiber-free diet with or without 25 g/kg PDX and 25 g/ kg lactitol for 1, 4, and 8 weeks. Compared to control, those who ingested PDX and lactitol had higher salivary IgA flow rates per weight of submandibular gland tissue at 4 and 8 weeks (P < 0.05), greater cecal weight and digesta at 1, 4, and 8 weeks (P < 0.05), and lower concentrations of short chain fatty acids (SCFAs) in cecal digesta (P = 0.0003). These findings suggest that the consumption of PDX and lactitol may upregulate salivary IgA secretion possibly by stimulating absorption of SCFAs produced by cecal fermentation. Thus, continuous ingestion of PDX and lactitol for up to 4 weeks could increase salivary IgA and promote immune defense against pathogen invasion through the oral route.

Faster Short-Chain Fatty Acid Absorption from the Cecum Following Polydextrose Ingestion Increases the Salivary Immunoglobulin A Flow Rate in Rats

“…Furthermore, it has been reported that the ingestion of PDX increases the IgA concentration in cecal digesta but simultaneously decreases the SCFA concentrations [20]. These results were replicated in our previous study, in which rats were fed a diet containing a combination of PDX and lactitol [21].…”

“…Salivary IgA flow rate (μg/10 min) was calculated by multiplying salivary IgA concentration (μg/mL) by salivary flow rate (mL/10 min) [ 23 ]. The salivary IgA flow rate normalized on the submandibular gland tissue weight (µg/10 min/g) was calculated as described in our previous studies [ 21 , 23 ].…”

“…In a previous study by Sepehr et al, rats were fed 50 g/kg of PDX [24]. However, we used a lower concentration of 40 g/kg of PDX because, in our previous study, rats suffered from diarrhea for several days after being fed 25 g/kg of PDX and 25 g/kg of lactitol [21].…”

“…We hypothesized that the SCFA increase in the rat cecum following FOS intake is likely to be involved in the increase of salivary IgA flow rate [22,23]. In contrast, rats fed a combination of PDX and lactitol showed an increased salivary IgA flow rate but also decreased SCFA levels in cecal digesta [21]. Furthermore, the effect of PDX ingestion on the pIgR expression levels remains unknown.…”

Xylitol’s Health Benefits beyond Dental Health: A Comprehensive Review

“…Mannitol can work as an antioxidant and protect hyaluronic acid in the skin [96]. Lactitol has been reported to stimulate secretory IgA production [97]. Erythritol causes no increase in blood serum glucose level [82].…”