Today’s post is the fourth in my series on natural killer cells (NK). We’ve already learned how they function and what dietary steps we can take to increase them.
But another lifestyle change may also strengthen natural killer cells: scientific evidence suggests we can increase their activity by remaining active ourselves.
After reviewing “multiple studies,” researchers from the University of Houston’s Laboratory of Physiology concluded:
“… [E]xercise can mitigate the… effects of age on immune function, thus increasing anti-cancer immunity. The… effect of exercise…. include[s] evidence that physical activity is able to stimulate greater NK-cell activity…”
Another study from Copenhagen’s Rigshospitalet compared the NK-cell activity and blood concentrations of “highly trained racing cyclists” and “untrained controls.”
The cyclists averaged 8-percent higher NK activity.
And in a randomized controlled trial from Loma Linda University, sedentary women who walked briskly for 45 min five days a week experienced increased NK activity and fewer upper respiratory tract infections after six weeks.
Weight Loss to Strengthen Natural Killer Cells
Interestingly, NK cells respond to exercise on a U-curve.
Too little exercise has a negative influence on them, but so does too much.
Weight gain is one of the most significant dangers failing to exercise poses for our immune systems. This Frontiers in Immunology review article from March 2020 ominously reports:
“Recent findings emphasize an impaired functionality… of natural killer (NK) cells under obese conditions.”
NK cells in obese people showed significantly lower cancer-fighting ability. They seem to congregate in areas of fat, possibly indicating a “… low grade inflammation of the fat tissue itself.”
Further, obesity heightens the NK cells’ activity levels, making them “… become exhausted much faster” and less able to defend our bodies against virus-infected cells and tumors.
When one of my friends was significantly overweight, merely crossing the street would exhaust him. What he was feeling outside his body was also happening inside his natural killer cells.
The extra weight he carried was exhausting his immune system! However, his story has a happy ending.
Plant-Based Food & Smart Exercise Strengthen Natural Killer Cells
After going 100-percent plant-based, my friend’s now at a healthy weight and feels better than ever!
In this Nutrition Facts video, Dr.Greger reviews a randomized trial in which obese individuals in a weight loss program experienced significant natural killer cell improvements after only three months.
However, there’s also evidence that exercising to the point of exhaustion may damage our immune system by generating “oxidative stress and an inflammatory state.”
Researchers recruited 25 experienced runners and split them into two groups of 12 and 13. Both groups trained six weeks for a 2.5-hour run.
However, only the 13-runner group ate a little over 1.5 cups of blueberries every day for the six weeks and then ate 2 cups one hour before the run began.
So, in the blueberry- vs non-blueberry runners contest, who won?
The truth is, the researchers didn’t care who crossed the finish line first. Their interest was in determining who had the stronger immunity, based on NK levels.
And from that standpoint, it wasn’t a race. It was a rout.
All 25 runners started with a normal count of around 2 billion NK cells. By the finish line, the non-blueberry runners’ count was approximately 1 billion, a 50-percent drop.
And the blueberry group coasted home carrying an NK load of 4 billion. They’d run just as far, yet finished with twice their starting count and four times more than their competitors’ final tally!
So the blueberries were enough to completely eradicate the “oxidative effects and inflammatory state” generated by the runners’ enormous physical effort.
And this explains why, after running five 5k races in a single day this January, the first thing I wanted to eat was a BIG BOWL OF BERRIES!