Capsaicin: Bringing synergy to combined feed additives

While valued foremost for its spicy taste, capsaicin is used in practical applications far beyond the kitchen or first-aid cabinet. When ingested, capsaicin has been shown to deliver health benefits to humans and animals, and it is no surprise that capsaicin is now also being used in the feed additive sector to improve gut health, well-being and livestock productivity.

Below, we review the health and performance benefits of capsaicin that make it an interesting feed additive ingredient to reduce inflammation, help digestion and to improve immune/infection resistance. We also consider modes of action and provide supporting examples from peer-reviewed scientific literature.

Anti-inflammatory effect

Inflammation is a process by which the immune system fights an irritant to protect the body against injury or infection. Bacteria, endotoxins (i.e. lipopolysaccharide, or LPS), and even some feed components or their metabolites can trigger inflammation. The immune activation associated with inflammation is a complex process requiring the well-orchestrated interaction of a wide array of specialised immune cells. In livestock, inflammation can lead to energy losses, poor feed efficiency, reduced performance and general morbidity.

Inflammatory processes are regulated by small intercellular protein messengers called cytokines. The pro-inflammatory cytokines maintain and amplify inflammation, while the anti-inflammatory cytokines dampen it. Using pig immune cells, researchers have shown capsaicin can regulate cytokine production and influence inflammatory processes. In the absence of an LPS challenge, capsaicin normalised the inflammatory processes, and when the LPS challenge was applied, it reduced the pro-inflammatory response. These findings were confirmed in another study where the anti-inflammatory effect of capsaicin was mediated by inhibition of the pro-inflammatory signalling pathway (NF-κB).

Intestinal health and digestion support

Both a healthy gut and efficient digestion begin in the mouth. Fluids excreted in the mouth of pigs and in the crop or proventriculus of poultry will bind and lyse viruses and bacteria, offering a first line of defence against pathogens. These fluids contain enzymes that initiate the breakdown of lipids and starches. Data from research shows that the concentration of the starch-digesting enzyme, α‐amylase, increases with the fluid flow rate, while capsaicin has been shown to increase fluid production and enzymatic activity. Other studies show that capsaicin increases bile acid secretion, promoting fat digestion.

The small intestine screens and controls:
The small intestine carefully screens and controls which molecules can enter the bloodstream of the host. It also trains the immune system to correctly recognise and respond to any possible threats that entered the gut. Epithelial cells lining the intestines are held together by proteins that line the tight junctions that help maintain gut homeostasis through regulating or blocking passage of pathogens, molecules and ions. Research data shows that capsicum oleoresin (a concentrated oil extract of capsaicin) alters the activity of ileal mucosa cells, as measured by the patterns of gene expression. Specifically, there is an increase in expression of genes related to integrity of epithelial cell membranes and tight junctions, which are both indicative of enhanced gut mucosa health.

Villi increase absorption capacity:
The lining of the small intestine is covered by villi, which are finger like projections that increase the surface area and absorption capacity. Between the villi are crypts (of Lieberkuhn), which extend down to the mucosae. Longer villi and smaller crypts characterise healthy intestines.

Protective mucus:
Finally, a coating of protective mucus comprises the top cover. Research data has shown an improvement in mucus production in chickens fed capsaicin (in a mix with carvacrol and cinnamaldehyde) as well as a thicker mucus layer covering the glandular stomach and jejunum. This effect results in a better protection of villi and increased villi length, especially in animals fed maize based diets. Longer villi are also shown to increase nutrient absorption and the thicker mucus layer provides an enhanced barrier against pathogens.

Immunity and infection resistance

Generally speaking, innate immunity involves non-specific immune responses and the stimulation of barrier and defence mechanisms, including mucus. In the chicken gut, the mucogenic effect of capsaicin supplementation has been shown to reduce the numbers and the risk of pathogenic bacteria adhesion (Escherichia coli and Clostridium perfringens). In turn, adaptive humoral immunity is more specialised and mainly involves antibodies (immunoglobulins), which are secreted by immune cells present in blood.

Stimulate immune response:
There is experimental evidence that a feed additive containing a combination of carvacrol, cinnamaldehyde, and capsicum oleoresin stimulated the innate and the adaptive (humoral) immune response. Researchers have also shown that chickens fed the capsaicin-containing additive were more immune to coccidiosis, which is also considered to be one of the main predisposing factors for necrotic and bacterial enteritis (dysbacteriosis).

Protective mechanism against infections:
The protective mechanism of capsaicin against infections, including both bacterial and necrotic enteritis, may be partially explained by the modulatory effect on the gut microbiome of the host and for effects on intestinal barrier function. The gut microbiome consists of a highly diverse ecosystem of mostly beneficial bacteria. These good bacteria help the host digest food and battle pathogen invasion via colonisation resistance. One study showed that a blend of capsicum and curcuma oleoresins reduced the negative consequences of necrotic enteritis infection on body weight and intestinal lesions, in part, through alteration of the gut microbiome. However, the authors also noted the degree of this effect was dependent on the breeds of commercial broilers used in the study.

The effect on necrotic enteritis

Necrotic enteritis has a major impact on health and mortality in broilers. Many factors can predispose birds to develop necrotic enteritis, but the most common are the concurrent infection with Eimeria maxima (coccidiosis) and Clostridium perfringens (an anaerobic, spore forming, α-toxin producing bacteria). Using a necrotic enteritis disease model in broiler chickens, researchers tested the effect of a blend of capsicum oleoresin and turmeric oleoresin and found that this blend had a number of beneficial effects. It not only improved the infection resistance of the birds, but also reduced the number of lesions and levels of pro-inflammatory cytokines in the intestines. It also lowered the infiltration of the α-toxin into blood serum and improved body weights of the infected animals.

Conclusion

Accumulating research explains the mechanisms and beneficial properties of capsaicin to help fight infections, modulate immune response, aid digestion and improve animal well-being and productivity. This hot bioactive is now also included in Trouw Nutrition Gut Health feed additives. Researchers are optimising combinations of capsaicin at relatively low inclusion levels along with other ingredients to benefit gut health. You might say the secret is in the sauce.

References available on request