Understanding Lactate: Beyond the 'Burn'
For decades, lactate, or the lactic acid it's associated with, was incorrectly blamed for muscle fatigue and soreness after exercise. Contemporary science, largely advanced by Dr. George Brooks' 'lactate shuttle' theory, has fundamentally shifted this perception. Lactate is now understood to be a valuable and clean-burning fuel source, constantly produced and used by various tissues in the body, even under fully aerobic conditions.
During high-intensity exercise, when energy demand outpaces oxygen supply, the breakdown of glucose produces lactate. This is not a failure of the system, but a strategic adaptation. Lactate is then shuttled from active muscle fibers to less active ones, as well as to the heart, brain, and liver, to be used as fuel. Supplementing with lactate aims to increase the availability of this fuel source, potentially impacting performance, recovery, and other physiological functions.
The Diverse Actions of Lactate in the Body
- Energy Production: Lactate is an efficient energy source that can be readily converted back to pyruvate in the presence of oxygen, where it enters the Krebs cycle to produce ATP. This process is particularly important during intense or prolonged exercise when muscle glycogen stores are depleted.
- Buffering Acidosis: The 'burn' sensation during intense exercise is caused by accumulating hydrogen ions, not lactate. However, lactate can act as a buffer, helping to consume these excess hydrogen ions, which in theory could delay muscle fatigue. While promising in theory, studies have yielded mixed results on whether supplements effectively enhance buffering capacity to improve performance.
- Brain Fuel: The brain, like other organs, can utilize lactate as an energy source, especially during periods of high demand or low glucose availability. Research shows lactate can cross the blood-brain barrier and has been linked to improved cognition, memory, and potential neuroprotective effects.
- Neuroplasticity and Mental Health: Lactate acts as a signaling molecule that can promote brain plasticity. Studies suggest it can upregulate the brain-derived neurotrophic factor (BDNF), a protein crucial for learning and memory. It may also have mood-enhancing effects, with animal studies showing it can reduce depression-like behaviors.
- Gut Microbiome Modulation: A meta-analysis published in ScienceDirect suggests that lactate supplementation can positively modulate the gut microbiome. It was found to increase beneficial bacteria like Lactobacillus and Bifidobacterium while decreasing potentially pathogenic species, with effects being dose- and age-dependent.
- Calcium Source (Calcium Lactate): When lactate is combined with calcium, the resulting supplement provides a source of calcium, an essential mineral for bone, nerve, and muscle health. This is distinct from the athletic performance effects of pure lactate or sodium lactate.
Lactate Supplementation for Athletes: The Evidence
Despite the promising physiological roles of lactate, its efficacy as a performance-enhancing supplement has been a subject of debate in sports science. Early studies and anecdotal reports suggested benefits, but more rigorous, double-blind, placebo-controlled trials have provided a more nuanced picture.
Some research has explored the effects of lactate supplementation on exercise performance, particularly during prolonged, high-intensity efforts. Some studies reported no performance advantages in endurance events like 20km cycling time trials, even with slightly reduced perceived exertion. Other, more specific studies, found that calcium lactate supplementation actually worsened repetitive sprint ability and other anaerobic performance measures in younger athletes. These conflicting results indicate that a simple increase in lactate availability does not guarantee a performance boost, and the dosage, timing, and type of supplement (e.g., sodium vs. calcium) all matter. More research is needed to determine optimal strategies.
Comparing Sodium Lactate and Calcium Lactate
Lactate supplements are most commonly sold as salts, either sodium lactate or calcium lactate. While both provide the lactate molecule, their accompanying mineral and other properties can impact their effects. The choice depends largely on the user's primary goal.
| Feature | Sodium Lactate | Calcium Lactate |
|---|---|---|
| Primary Goal | Sports performance, buffering | Calcium deficiency, bone health |
| Mechanism | Replenishes blood lactate and sodium. Sodium may enhance lactate uptake. | Provides a source of calcium for dietary needs. |
| Performance Impact | Some studies suggest potential for better buffering and perceived exertion, though performance results are mixed. | Less effective for athletic performance compared to bicarbonate. |
| Potential Side Effects | High doses can cause gastrointestinal distress, metabolic alkalosis, and potential cardiovascular effects in some individuals. | Constipation, nausea, bloating. Excess intake can cause hypercalcemia. |
| Mineral Contribution | Increases sodium levels. | Provides a less bioavailable source of calcium compared to other salts like calcium citrate or carbonate. |
Side Effects and Safety Precautions
Like any supplement, lactate can cause side effects, particularly with excessive intake or specific forms. Sodium lactate, often used for performance, can lead to side effects like confusion, mood changes, muscle pain, and an irregular heartbeat if taken in high doses. Calcium lactate, when used to boost calcium intake, can cause gastrointestinal issues such as constipation, nausea, and upset stomach. Overdosing on calcium lactate can also lead to hypercalcemia, or dangerously high levels of calcium in the blood. It is crucial to follow dosage instructions and consult a healthcare professional, especially if you have pre-existing conditions or are taking other medications, as lactate can have interactions with diuretics, antibiotics, and heart medication.
Conclusion
The perception of lactate has evolved from a simple waste product to a dynamic and valuable metabolic molecule. Lactate supplementation offers a way to leverage this molecule for a variety of potential benefits. For athletes, it serves as an alternative fuel and a potential buffer, although its ergogenic effects are still debated and appear inconsistent across different sports and conditions. Beyond performance, lactate has shown promise for brain health, influencing cognition and neuroplasticity, and for improving the balance of the gut microbiome. While the research is promising, the effects are highly dependent on the type of supplement and individual response. As with any supplement, a cautious and informed approach, coupled with a healthy lifestyle, is the best path forward.
Learn more about lactate's role in health and exercise metabolism from this comprehensive review: The contemporary role of lactate in exercise physiology and medicine.
