Lactate and Cancer Risk: The Role of Strenuous Exercise


Twitter isn’t all bad. This week I was scrolling through my feed and came upon a post from Inigo San Millan, an Assistant Professor at the University of Colorado School of Medicine and the Director of the Sports Performance Program at the CU Sports Medicine and Performance Center in Boulder, Colorado. The headline that caught my eye read: “Lactate May Be Key For Cancer Development”.

My immediate thought was: That can’t be good.

Athletes get worried when headlines imply a connection between exercise and an increased risk of injury, illness, or death. At 56 years old, I’m one of them. When I clicked on the link to Medical News Today, what I read compelled to me go find the full research paper.

What The Study Does NOT Say

Athletes could interpret the article’s title to imply strenuous exercise increases the risk of developing cancer. When strenuous exercise increases the demand for energy and the mitochondria in muscle cells reach the limit for how quickly they can break down carbohydrate and fat through aerobic metabolism, carbohydrate can be partially broken down using the metabolic shortcut of glycolysis. This liberates the much-needed energy and produces lactate.

If producing a lot of lactate caused cancer, Olympians would die very young. In fact, there would be an epidemic of cancer among amateur, elite, and even recreational athletes. Everybody produces lactate, every minute of every day. Athletes produce even more of it. Thankfully, despite how the title can be interpreted, the article does not assert any increase in cancer risk in connection with strenuous exercise.

The Lactate and Cancer Connection: The Warburg Effect

I’m sure I won’t do Dr. San Millan’s study justice in my simplified explanation, but he and his colleagues took a novel approach to an old mystery. Back in the 1920s, Otto Warburg discovered cancer cells consume a lot more glucose and produce a lot more lactate – even when there is sufficient oxygen available for aerobic metabolism – compared to healthy cells. Known as the Warburg Effect, this may be initiated by changes that hinder the function of a cell’s mitochondria. 

As Dr. San Millan points out, much of the ensuing research focused on the glucose end of the equation, with the goal of slowing or reversing the growth of cancerous tissues by disrupting the exchange of lactate between and within cells. Advocates of nutritional ketosis (fueling the body with ketone bodies derived from fat) often point to slowing or stopping the growth of cancer cells through starvation (reduced availability of glucose) as one of the biggest health benefits of the high fat, very low carbohydrate nutritional strategy. According to San Millan, however, “oncogenes” (genes with the potential to cause cancer) are the driving force behind the dramatic increase in glucose metabolism by cancer cells, not the carbohydrate you eat. Even without consuming carbohydrate, a triad of oncogenes (HIF-1, c-MYC and p53) can feed aggressive cancers by stimulating the breakdown of protein from skeletal muscle and converting it to glucose through gluconeogenesis. This is part of the reason cancer patients suffer muscle wasting (cachexia); protein is being converted to glucose to feed cancer cells. 

A Novel Look at the Warburg Effect

One of the mysteries of the Warburg Effect is that it doesn’t make evolutionary sense. Evolution moves toward greater efficiency, not the other way around. Compared to aerobic metabolism, glycolysis is a far less efficient way to produce energy from carbohydrate. If you think of cancer as a parasite, overconsumption of glucose contributes to substantial weight loss, weakens its host, and hastens its own death. Again, that is contrary to the normal process of evolution.

What if dysregulated lactate production is the purpose of cancer?

Dr. San Millan and other researchers looking at the lactate production side of the Warburg Effect hypothesize that dysregulated lactate production sets the stage for cancer cells to thrive, multiply, spread, and metastasize. Cancerous tumors establish a acidic microenvironment around them. This may help protect cancer cells from the body’s immune system, as well as create an environment conducive to the growth and spread of new cancer cells. The release of lactate into the bloodstream causes a chronic exposure to lactate throughout the body, as opposed to short-term spikes in blood lactate from strenuous exercise. Normally, the presence of lactate causes the up-regulation of mitochondrial activity in order to break it down for fuel. According to the abnormal lactate metabolism theory of cancer, cancer may spread when an anomaly causes a down-regulation of mitochondrial activity in the presence of lactate, thus increasing that cell’s glycolytic activity, producing more lactate, and establishing an environment conducive to the growth of more highly-glycolytic cancer cells.

“To Stop Cancer You Have To Stop Lactate”

In the Medical News Today article, Dr. Millan is quoted as saying, “to stop cancer you have to stop lactate” because the presence of lactate is required for five essential steps of cancer development: angiogenesis (creation of new blood vessels inside tumors), immune escape (how cancer cells outmaneuver the immune system) cell migration (how cancer spreads), metastasis (development of additional tumors), and self-sufficient metabolism. Going back to the evolutionary conundrum, dysregulated lactate production starts to make sense if lactate is essential for creating the conditions necessary for an organism to thrive, replicate, and spread.

You’re probably still thinking this sounds pretty bad for athletes who chronically produce a lot of lactate, right?

Here’s where we get to the good news.

The Protective Effect of Exercise

Endurance exercise has been repeatedly shown to increase an athlete’s ability to produce energy via glycolysis. Exercise also accelerates the rate at which the resulting lactate gets reintegrated into aerobic metabolism and broken down for energy. To quote Dr. San Millan’s paper:

“[O]ne of the most impressive adaptations to metabolic stress in mammalian biology is doubling of mass of the muscle mitochondrial reticulum due to endurance exercise training. Increased muscle mitochondrial density due to endurance training allows for increased respiratory control, increased fat metabolism and greater lactate clearance in muscles working at a given exercise power output. As well, by increasing lactate clearance via oxidation and gluconeogenesis, high muscle mitochondrial density and other physiological and metabolic adaptations allow for high rates of muscle glycolysis to be tolerated because of correspondingly high lactate clearance rates. However, while high mitochondrial density provides a metabolic underpinning for exercise capacity, mitochondrial dysfunction is disastrous for lactate clearance in cancer.”

Stopping lactate production in healthy people as a means of preventing cancer would be difficult because lactate production is a normal process in cells throughout the body. However, increased aerobic fitness increases your ability to produce energy through aerobic metabolism and reduces reliance on glycolysis. Fitness also boosts the rate and amount of lactate you can break down for fuel, thereby burning up the precursor required for each of the 5 key steps in cancer’s development. In other words, when abnormal lactate metabolism happens somewhere in your body, increased fitness may be key to preventing that anomaly from establishing an environment in which cancer cells can survive, multiply, and reach a critical mass necessary to support a tumor. 

Dr. San Millan also points out that cells communicate by releasing exosomes (vesicles containing cellular material). Cancer cells release exosomes that facilitate the spread of cancer. Increased aerobic fitness may counteract this communication by increasing the exosomal communication coming from healthy skeletal muscle cells, and since there are so many more skeletal muscle cells compared to cancer cells, the effect may be akin to a large crowd drowning out the speech of a small but vocal hate group.

To take these ideas a step further (and into the land of speculation), if increased ability to break down lactate for energy has a protective effect against the development of cancer, then perhaps lack of fitness (can’t process lactate quickly) and an overabundance of available glucose (lots of tumor-friendly fuel) could partly explain why sedentary people who consume lots of sugar have a higher incidence of cancer than athletes (some of whom also consume a lot of sugar). It may also help explain why the incidence of cancer increases as societies and nations develop technologies that reduce the energy expenditure required for activities of daily living. At some level, fitness is fitness, whether it’s the result of carrying water from the river or training for a triathlon.

Summary: Exercise is neither the cure nor cause of cancer

I think the medical profession would agree with the statement that it’s unlikely there is a unifying cause of all cancers (not even genetics), but rather that it is a class of diseases caused by a multifactorial process. Exercising is good for your health for a wide range of reasons and the increased ability to process lactate might be one of them. As Dr. San Millan’s study concludes, a greater research emphasis on the lactate-cancer connection, including the role exercise can play in the prevention and treatment of cancer, could open the doors to both exciting new medical treatments and public health policies!

Chris Carmichael
CEO/Head Coach of CTS

San-Millan, Inigo, and George A. Brooks. “Reexamining Cancer Metabolism: Lactate Production for Carcinogenesis Could Be the Purpose and Explanation of the Warburg Effect.” Carcinogenesis (2017) 38 (2): 119-133.

12 Responses to “Lactate and Cancer Risk: The Role of Strenuous Exercise”

  1. Jimbo on

    What do you think about a product sold in practically every bike shop called Sportlegs which provides lactate? I’m wondering now if it’s harmful to use this product and actually add lactate to my pre-ride nutrition.

  2. Dr. Vrzal on

    Very intriguing perspectives presented. I will definitely be exploring the correlations between lactate, cytochrome p450 and methylation as they pertain to cancer. Why confidently encouraging aerobic activities.

  3. rusty on

    are we talking the production of lactic acid or what women do when feeding their child (lactating?)…or am I missing something?

  4. David Wink on

    I have to wonder about this? My colleagues and I study this precise aspect of cancer. Cancer is a systemic problem involving many aspect beyond the warburg effect. Lactate systemically and the ability to handle it seems to be better rather a simple burst one experiences during excersices. Excersice improves a the immune system overall. I will look at this since me and my colleagues review for numerous journals including in carcinogenesis. Keep on excerising remember the number one cause of premature death is caused from cardiovascular disease and excerise is good. Lactate and metabolism is complex in the tumor microenvironment and this address a small part.

    • CTS on

      Dr. Inigo San Millan’s work is quite interesting, and I think he would agree with your sentiment that the relationship between dysregulated lactate production and metabolism is just one of many factors that influences the development of cancer. Similarly, we certainly don’t dispute that exercise – including strenuous exercise – is good for both health and performance. – CTS

  5. charles hufman on

    Many athletes who had cancer fought it off with exercise. From a medical standpoint your article made sense. One should be sensitive to the over consumption of refined sugars and sugar substitutes which studies have already shown encourage cancer. Using only the glucose that the body needs and no more may be the key. We produce lactate all the time in our bodies and I’m quite sure that sedentary habits and obesity are bad news for those who are concerned with cancer. Meanwhile I will pedal on ☺

  6. Jay Romick on

    There have been a number of clinical studies that have demonstrated the protective affect of exercise in patients being treated for cancer. It appears to increase the efficacy of chemotherapy, which affects whether the cancer comes back, or how long before it comes back (increasing progression free survival). It has been shown more recently that exercise is as effective, if not more effective, than medical treatments in dealing with chemo related fatigue.

  7. Ben Reiter MD on

    There is nothing in the article that even remotely suggests that increased lactate causes cancer. As you stated in your article, the author postulates that cancer cells adapt by producing a high lactate environment which may make help their survival and avoid immune regulation. The article states that preventing this adaption may lead to effective anti-cancer drugs.

    I would therefore postulate that high intensity exercise, which can lead to more effective lactate metabolism, would actually lower the risk. Indeed, in a recent article (Epidemiol Rev. 2017 Apr 27:1-22. doi: 10.1093/epirev/mxx007. [Epub ahead of print]
    The Impact of Exercise on Cancer Mortality, Recurrence, and Treatment-Related Adverse Effects. Cormie P, Zopf EM, Zhang X, Schmitz KH.) the authors find “patients who exercised following a diagnosis of cancer were observed to have a lower relative risk of cancer mortality and recurrence and experienced fewer/less severe adverse effects. The findings of this review support the view that exercise is an important adjunct therapy in the management of cancer. Implications on cancer care policy and practice are discussed.”

    There are many other studies, as I am sure you know, that show exercise leads to longer and healthier lives; and intense interval training actually makes our mitochondria work better. I see this discussion as another mis-interpretaton of a researcher’s speculative article.

    • CTS on

      We appreciate your thoughtful comment, but find it a bit confusing. Your comment agrees with the content of the article, and then you say we mis-interpreted the study. Dr. San Millan’s study suggests improved lactate metabolism may reduce the risk of developing cancer, or at least hinder its growth and spread. Perhaps we did not do a good enough job making our point clear in the article, but our intent was to support the hypothesis that improving aerobic fitness – which includes metabolic adaptations that increase oxidation of fat and carbohydrate as well as improve lactate metabolism – may have a protective effect against the development, growth, and spread of cancer (in addition to a host of other positive health and performance benefits. – CTS

  8. Ernesider on

    “Cycling is anaerobic”

    “When cycling, especially while racing, we use a mix of aerobic and anaerobic energy to create speed for the day. While sprinting hard to close a gap in a road race or powering up a steep climb on a dirt trail, you’re tapping into both aerobic and anaerobic metabolism to complete the task, but most of the time you’re working aerobically.”
    Training Peaks – How Important is Anaerobic Energy in Cycling? Part 1

    “His recommendation is not to exceed 30 minutes of “aerobic” exercise.”
    That seems totally absurd to me and why the quotation marks around aerobic..??

  9. rgeebee on

    I read a lot of Dr Russel Blaylock’s “reports” which are available thru Newsmax – you pay for a year’s subscription. He has written about the effects of aerobic exercise causing a “flood of oxidants” (which is why we consume effective anti-oxidants). His recommendation is not to exceed 30 min of “aerobic” exercise. He recommends doing weight training instead since oxidative stress is much less. Cycling is anerobic, so it’s a combination of high heart rate plus muscle building (quads, etc). So I’ve always wondered where it fits. He never mentions a link between lactate and cancer and he’s written many very interesting articles on cancer, and prevention and treatments using nutrition…..


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