Heat killed lactic acid strain boosts athletes' immune defenses

Japanese researchers associated with a medical school in Japan and with the supplier of the test material used a heat-killed version of the strain Lactococcus lactis JCM 5805, which is branded by its manufacturer, Kyowa Hakko Kirin, as LC-Plasma.  

Lactococcus lactis is a species that is often used in the food industry to ferment yogurts and cheeses. Kyowa Hakko Kirin says it discovered its proprietary strain in 2011, and says it has a unique property.

Activating key immune system component

The company says this strain is the only lactic acid bacterium that has been confirmed to directly activate Plasmacytoid dendritic cells (pDCs) — which together act as the "commander in chief" of the immune system. Kyowa Hakko Kirin says it now has more than 13 studies published on the strain, which includes studies using live cells (colony forming units, or CFUs) or cells that have been killed via heat treatment. 

The team's findings on the unique activity of Lactococcus lactis strain add to the story of another study published earlier this year in which the bacterium boosted the immune systems of immature mice. Research on other strains in the same species have noted its anti inflammatory potential.

In this most recent study, published in the Journal of the International Society of Sports Nutrition, the researchers recruited 51 male subjects who were members of “a university sports club” who were divided into placebo and intervention groups. After the exclusion of one subject, the groups ended up being 24 and 26 subjects in size, respectively. 

The subjects received 100 billion cells of the heat-killed bacterium in a capsule or a placebo daily for 13 days while they continued their “high intensity exercise according to their sports club training regime.” The athletes competed variously in track and field events, soccer, and futsal, which is a variant of soccer played on a hard surface, often indoors.

The primary measures were number of days experiencing cold and flu symptoms. Secondary measures included muscle damage and fatigue.

The upper respiratory tract infection response was measured by cumulative days with URTI or symptoms like sniffles or runny noses reported among the athletes. Also, days with significant fatigue symptoms were measured as well.

Significant effect on respiratory infections and fatigue

On both of these measures, the LC Plasma supplement showed a significant effect, according to the researchers. For example, on the URTI measure, in the placebo group there were 56 cumulative days with an URTI reported, versus 256 without. In the intervention group, the figures were 39 days and 299 days, respectively (the total number of days are unequal because of the different size of the groups).

For the fatigue measure, for the placebo group experienced 128 cumulative days with significant fatigue symptoms reported, versus 182 without. In the intervention group, the figures were 110 days and 225 days respectively.

The researchers found no significant effect on muscle damage and stress. 

The improvement in the URTI and related symptoms measures were attributed to the pDC activation, an effect that matches up with previous studies on the strain. The reduction in fatigue was more intriguing, the researchers said.

“Here we show for the first time that [lactic acid bacteria] material such as LC-Plasma supplementation was effective for improving fatigue during consecutive [days of high intensity exercise]. For people under physically stressful conditions such as athletes, fatigue accumulation is a serious problem, therefore our finding is valuable for athletes,” the researchers said.

Source: Journal of the International Society of Sports Nutrition

2. August 2018 15:39 doi.org/10.1186/s12970-018-0244-9

“Efficacy of heat-killed Lactococcus lactis JCM 5805 on immunity and fatigue during consecutive high intensity exercise in male athletes: a randomized, placebo-controlled, double-blinded trial”

Authors: Komano Y, Shimada K, Naito H, et al.