Can Chlorella Offset Low Immunity During Intense Training?

Do you like to exercise hard? Are long and grueling training sessions a regular part of your routine? If so, the research shows you’re more likely to get sick or experience adverse symptoms similar to a cold or flu.(1,2) Contrary to popular belief, it’s not simply a high total training load that depletes immunity, but rather how abruptly your training ramps up that leaves your immune system compromised and susceptible to attack.(3)

In fact, experts have uncovered dramatic increases in training volume are perhaps a better predictor of upper-respiratory tract infection (URTI) than just your training load alone.(4) However, as an athlete you often have no choice, you have to push the accelerator to the floor and train hard to compete with the competition.  

This is an area where supporting the body via diet and supplementation can add some extra support to protect you from infection or adverse symptoms, so your progress doesn’t go off the rails before a major competition. The difficult part is figuring out just what foods or supplements to add. Let’s take a closer look at food-based supplement that may hold some promise for athletes.

What Is Chlorella?

Chlorella is a round, green micro-algae rich in chlorophyll that grows only in fresh water. It’s tremendously nutrient-dense, but cannot be broken down by the human digestive tract due to its hard cell wall, and thus can only be consumed via supplementation. Chlorella is a complete protein source containing all essential amino acids, a significant source of iron and vitamin C, as well as 100mg of omega-3 fats per teaspoon.(5,6,7) It’s also a tremendous antioxidant, containing several potent free radical scavengers such as chlorophyll, vitamin C, beta-carotene, lycopene and lutein.

In terms of immune system function, chlorella has a unique ability to enhance innate immunity - your body’s “first line of defense” against infection - by increasing natural killer cell activity and thus protecting you from catching a nasty cold or flu. (8)

The important question for athletes is can supplementation during training help as you ramp up training to peak for high performance and competition? While the research is limited, there are some interesting findings.

Chlorella & Athlete Immunity

A recent study in the European Journal of Nutrition looked at the benefits of chlorella on immune function in athletes ramping up training intensity over a two-day period. Twenty-six recreational athletes participated in the study, with half the group receiving 6g of chlorella daily (divided between breakfast and dinner) and the other half a placebo. Baseline levels of secretory IgA – a well-recognized biomarker of the first line of defense protecting the intestinal epithelium from gut pathogens - were taken at the outset of the study, after 4 weeks of basic training, then again at 5 and 6-week marks.(9) At the 4-week mark, the athletes engaged in two-a-day intense training sessions in the morning and afternoon. On Day 1, the first training session was a step-wise maximal oxygen test, followed by a second training HIIT training bout in the afternoon. On Day 2, the first session was a long endurance ride followed by another HIIT session in the afternoon.

What impact did the chlorella supplementation have on the cyclists?

The sIgA levels in the chlorella group were significantly higher after the two-day intensive training block compared to controls. (10) Previous research shows as secretory IgA levels increase, risk of colds and flus decreases in athletes. (11,12,13,14) Therefore, these results suggest athletes could be more protected from colds and flus with chlorella supplementation (however no differences in infections or symptoms were seen in the study). (10)

So, what does all this mean for you the athlete? The research on chlorella and performance isn’t very robust, but it is quite interesting.

The polysaccharides and glycoproteins present in chlorella have been shown in previous studies to boost immune system function. (15,16) It’s also been shown 4-8 weeks of chlorella supplementation does have a significant effect on increasing sIgA levels, and one study in particular on Japanese marital artists found chlorella was able to buffer decreases in sIgA during intensive training compared to controls. (17,18)

The Bottom Line: Chlorella supplementation, 6g per day 2-4 weeks out from a training peak, may be a simple and effective strategy to support immunity for athletes pushing themselves hard in preparation for competition.

Secretory IgA is your body’s first line of defense against foreign invaders. Low levels of sIgA have been associated to increased risk of URTI and the associated adverse symptoms. The ability to offset the increased demands on your immune system when peaking for competition is crucial for high performing athletes.

Chlorella is a nutrient-dense, convenient supplement option that can be added into protein shakes as a powder in the morning, or taken in capsule form during meals. If you’re looking for added immune protection as you peak for performance, chlorella supplementation may hold promise as you ramp up your training to reach the top of the podium.

Dr. Marc Bubbs ND, CISSN, CSCS