Abstract
BACKGROUND/OBJECTIVES: Enteral nutrition formulas with immune-enhancing nutrients, such as n-3 fatty acids, may manage patients’ nutritional status and pathophysiological processes. The aim of our study was to investigate natural killer (NK) cell activity alterations and related cytokine changes resulting from feeding with soybean oil-containing enteral nutrition formula (control group) and plant-derived n-3 fatty acid-enriched enteral nutrition formula. SUBJECTS/METHODS: Subjects participated for 14 consecutive days and consumed enteral formula containing canola and flaxseed oil (n3EN, test group) in nonsurgical patients hospitalized for rehabilitation. Blood samples were collected on the first day and 14 days after the consumption of each formula daily, and anthropometric parameters were collected. Hematology and biochemical values were analyzed, and NK cell activities and serum cytokine concentration were measured. A total of sixty subjects were included in the analysis, excluding dropouts. RESULTS: No significant differences were found in biochemical parameters. The n3EN group’s NK cell activities at effector:tumor cell ratios of 10:1, 5:1, 2.5:1 and 0.625:1 were significantly higher than those of the control group after two weeks (P < 0.05). However, there were no statistically significant differences in serum cytokine interleukin (IL)-12, interferon-γ, IL-1β, IL-6 and tumor necrosis factor-α values between the two groups. CONCLUSIONS: In conclusion, this study elucidates the beneficial effects of plant-derived n-3 fatty acid supplementation in enteral formula on NK cell activity.
Link to Full Text
Key Points
Enteral nutrition is preferred over parenteral nutrition for hospitalized patients who are unable to meet their nutritional requirements with an oral diet. Immune-enhancing enteral nutrition formulas containing n-3 fatty acids, selenium, and antioxidants may manage patients’ nutritional status and pathophysiological processes. The fat sources traditionally used in enteral nutrition are based on n-6 fatty acid-rich oils, such as soybean oil; however, such sources may not be ideal because they may provide excess linoleic acid which is a precursor for pro-inflammatory arachidonic acid synthesis [6]. Meta-analyses of controlled, randomized clinical trials using n-3 fatty acids or similar formulas to enhance immune functions have shown marked decreases in the length of hospital stay and infection events; however, these effects are more significant in critically ill or postoperative patients.
Therefore, the goal of this research was to compare NK cell activity alterations and related cytokine changes associated with a soybean oil formula (control) and a plant-derived n-3 fatty acid-enriched formula (test) in nonsurgical patients hospitalized for rehabilitation.
In this randomized, placebo-controlled study, the main findings indicated that the use of canola and flaxseed oils for enteral nutrition can be effective for activating the immune system by enhancing NK cell activities. Compared with the soybean oil formula (control) group, the plant-derived n-3 fatty acid-enriched formula group showed significantly greater increases in changes in NK cell activities at 10:1, 5:1, 2.5:1 and 0.625:1 E:T ratios. This immune-modulating finding in our study shows that plant n-3 fatty acids had beneficial effects on NK cell activity, a marker of immune competence.
NK cells are a crucial factor in the innate immune system, representing 10% of the cells in the total peripheral blood mononuclear cell (PBMC) population of circulating human lymphocytes. Decreases and increases in NK cell activity levels are related to the production of cytokines. A decrease in the expression level of NK cells results in altered production of cytokines.
Although the canola and flaxseed oil formula group had higher NK cell activity levels in this study, no significant changes were observed in the five measured cytokines: IL-12, IFN-γ, IL-1β, TNF-α and IL-6. Serum cytokine changes between the two groups and within the groups after two weeks of consuming each formula were not remarkable. The data demonstrated a greater increase in NK cell activity in the n3EN group. Immune-enhancing enteral nutrition enriched with canola and flaxseed oils yielded significant elevations in NK cell activities compared with the baseline levels, and a greater increase was observed in the n3EN group than that in the control group. In conclusion, this study shows the beneficial effects of plant-derived n-3 fatty acid supplementation in an enteral formula on NK cell activity.