Tag: supplements

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As of September 2017, new Sweat Science columns are being published at www.outsideonline.com/sweatscience. Check out my bestselling new book on the science of endurance, ENDURE: Mind, Body, and the Curiously Elastic Limits of Human Performance, published in February 2018 with a foreword by Malcolm Gladwell.

- Alex Hutchinson (@sweatscience)

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We all know caffeine helps exercise performance. Long, short, power, endurance, whatever. I wrote a Jockology column on it for the Globe back in 2008; Gretchen Reynolds had a round-up of the latest research in the New York Times a couple of days ago. So what more is there to say?

Well, if you want to get into the nitty-gritty, there’s a really interesting round-table discussion in the current issue of (wait for it) the Journal of Caffeine Research. It’s freely available online, and it’s not a research paper or a study — it just brings together a bunch of the leading researchers and practitioners in this area from around the world (like Terry Graham from the University of Guelph and Greg Cox from the Australian Institute of Sport) and gets them to air their opinions, thoughts, suspicions and doubts about how and in what contexts caffeine really works.

It turns out things are quite a bit more complicated than you might think. For example, Reynolds in the Times writes:

Caffeine has been proven to increase the number of fatty acids circulating in the bloodstream, which enables people to run or pedal longer (since their muscles can absorb and burn that fat for fuel and save the body’s limited stores of carbohydrates until later in the workout).

However, in the roundtable discussion, Graham disagrees with that statement. In fact, he makes a very broad argument:

I would take the controversial position that the ergogenic effect is not because of an alteration in either blood flow or alteration in delivery of blood-borne metabolites (fuels).

Instead, he believes the evidence points to effects in the muscle itself enhancing contractions, which would explain why it seems to work for virtually every sport. And the others appear to agree.

Interestingly, the editor-in-chief of the journal, Jack James of the National University of Ireland, proposes a totally contrary position. What if the supposed “ergogenic” effects of caffeine are really just due to the fact that, in virtually every study of caffeine, the subjects come to the lab in a state of withdrawal from not having had their usual morning dose? That, apparently, is what the evidence now suggests in studies of caffeine’s mental effects:

What we are talking about here arises from the fact that almost the entire population is exposed to caffeine on a regular basis, and studies show that decrements in psychomotor performance and mood are detectable after as little as 6–8 hours after caffeine was last ingested. Standard double-blind trials involve a brief pre-test period of caffeine abstinence, typically involving overnight abstinence to coincide with usual caffeine consumption patterns. By morning, participants are in the early stages of withdrawal and are experiencing negative withdrawal effects on cognitive performance and mood. When caffeine is then re-ingested under laboratory conditions, participants typically show improvements in performance and mood. However, studies that have controlled for withdrawal effects have repeatedly shown that the observed improvements are due to the reversal of withdrawal effects. That is, for cognitive performance, there is  little or no genuine net effect of caffeine over and above reversal of the negative effects caused by caffeine withdrawal. As such, can we be satisfied that this source of confounding has been adequately controlled in studies of physical performance?

It’s an interesting question. There are lots of other interesting nuggets in the discussion, on topics like dosage, responders vs. non-responders, whether habitually consuming caffeine reduces its ergogenic effects (Graham says no), and so on. In all cases, what you realize is that the literature is far less clear than we might have thought. The book on caffeine isn’t quite closed yet after all.

THANK YOU FOR VISITING SWEATSCIENCE.COM!

As of September 2017, new Sweat Science columns are being published at www.outsideonline.com/sweatscience. Check out my bestselling new book on the science of endurance, ENDURE: Mind, Body, and the Curiously Elastic Limits of Human Performance, published in February 2018 with a foreword by Malcolm Gladwell.

- Alex Hutchinson (@sweatscience)

***

I wrote last month about emerging evidence that taking antioxidant supplements may actually be counterproductive, especially for athletes. There’s an interesting paper coming up in Cell Metabolism that casts further doubt on the whole basis of our belief that (a) oxidative stress is what causes aging and other cellular damage, and (b) antioxidants can counteract these effects (press release here; abstract here).

What’s new about the study is that they didn’t use the typical indirect methods to guess about levels of reactive oxygen species (ROS – the bad guys) and antioxidants, averaged over the entire body. Using transgenic fruit flies, they were able to measure ROS activity directly and in real time, in different parts of the body. There are a whole bunch of surprising results in this study that fly in the face of the conventional antioxidant theory. A few of the key ones:

• If oxidation is linked to aging, we’d expect to see more ROS as the flies get older. In fact, ROS levels stay constant throughout the aging process except in the intestine. Only the intestine shows gradually increasing levels of oxidation.
• Even in the intestine, the flies who lived longest had ROS levels that increased more quickly than the flies who died earliest — exactly the opposite of what we’d expect if oxidative stress is linked to aging and eventual death.
• When the flies were fed an antioxidant, their production of ROS increased in response.

This last point, of course, is most interesting from the perspective of supplementation. It suggests that there’s a homeostatic response that attempts to preserve the balance between oxidants and antioxidants at a roughly constant level. So if you take a lot of antioxidants, your body simply ramps up its level of oxidants in response — with who knows what effect!

Let me emphasize: this is a study of fruit flies. Fruit flies are not humans. Still, the results suggest that our basic understanding of the real-time dynamics of oxidant-antioxidant interactions is far from complete. Now, I’d happily ignore all this cell biology stuff if there were lots of controlled trials showing increased health or performance from antioxidants. If it works, who cares about the mechanism? But since (a) we have no consistent evidence that antioxidants work, and (b) it’s increasingly clear that we don’t even understand how or why they should work, or what supposed problem they’re supposed to fix, I still think a balanced diet with lots of brightly coloured fruits and veggies in the way to go. Not powders, and not pills.

THANK YOU FOR VISITING SWEATSCIENCE.COM!

As of September 2017, new Sweat Science columns are being published at www.outsideonline.com/sweatscience. Check out my bestselling new book on the science of endurance, ENDURE: Mind, Body, and the Curiously Elastic Limits of Human Performance, published in February 2018 with a foreword by Malcolm Gladwell.

- Alex Hutchinson (@sweatscience)

***

The December issue of Sports Medicine has an enormous, detailed review of research on the effect of antioxidant (i.e. vitamin C, vitamin E, coenzymeQ10, etc.) supplements on training. To most people, this seems like a no-brainer: what could be smarter than popping a multivitamin as “insurance” in case your diet isn’t giving you all the vitamins you need? But (as I’ve blogged about before) there’s an emerging school of thought arguing that taking antioxidants can actually block some of the gains you’d otherwise get from training. Here’s how I explained the debate back in April:

The traditional theory goes like this: strenuous exercise produces “reactive oxygen species” (ROS), which cause damage to cells and DNA in the body. Taking antioxidant supplements like vitamins C and E helps to neutralize the ROS, allowing the body to recover more quickly from workouts.

The new theory, in contrast, goes like this: strenuous exercise produces ROS, which signal to the body that it needs to adapt to this new training stress by becoming stronger and more efficient. Taking antioxidant supplements neutralizes the ROS, which means the body doesn’t receive the same signals telling it to adapt, so you make smaller gains in strength and endurance from your training.

The new paper comes down firmly on the side of the latter view:

The aim of this review is to present and discuss 23 studies that have shown that antioxidant supplementation interferes with exercise training-induced adaptations. The main findings of these studies are that, in certain situations, loading the cell with high doses of antioxidants leads to a blunting of the positive effects of exercise training and interferes with important [reactive oxygen species]-mediated physiological processes, such as vasodilation and insulin signalling.

So is this definitive? Far from it. As the review notes, there have been a few studies that found beneficial effects of antioxidant supplements on exercise performance, tons that have found no effect, and a few (23, to be exact) that have found negative effects. What most of the studies have in common:

As commonly found in sports nutrition research, the vast majority do not adhere to all the accepted features of a high-quality trial (e.g. placebo-controlled, double-blind, randomized design with an intent-to-treat analysis). Indeed, most studies fail to provide sufficient detail regarding inclusion and exclusion criteria, justification of sample size, adverse events, data gathering and reporting, randomization, allocation and concealment methods, and an assessment of blinding success. The poor quality of the majority of studies in this field increases the possibility for bias and needs to be always considered when evaluating the findings.

This is a really important point to bear in mind, and not just when it comes to sports nutrition. Whatever the supplement, training method, or piece of equipment you’re talking about, there’s nearly always a crappy, poorly executed study that seems to “prove” that it works. So where does that leave us? On this topic, I’m in agreement with the authors:

We recommend that an adequate intake of vitamins and minerals through a varied and balanced diet remains the best approach to maintain the optimal antioxidant status in exercising individuals.

THANK YOU FOR VISITING SWEATSCIENCE.COM!

As of September 2017, new Sweat Science columns are being published at www.outsideonline.com/sweatscience. Check out my bestselling new book on the science of endurance, ENDURE: Mind, Body, and the Curiously Elastic Limits of Human Performance, published in February 2018 with a foreword by Malcolm Gladwell.

- Alex Hutchinson (@sweatscience)

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Marion Nestle has an interesting blog post about the two most recent studies that fail to find benefits from taking vitamin supplements. (One study followed 38,772 women for 22 years, and found that those taking multivitamins or certain single vitamins were slightly more likely to die than those not taking any supplements; the other was a placebo-controlled trial of 35,533 men, which found that taking 400 IU per day of vitamin E increased the risk of prostate cancer during a 12-year follow-up.)

The reason I’m posting this isn’t that I think vitamins will kill you — the effects were small, and for the most part I think supplements tend to do nothing, rather than have big effects either way. Personally, I suspect that the most negative effect of vitamin supplements is the feeling of false healthiness they provide, which then allows you to justify making other, less healthy choices throughout the day.

Anyway, what I found most interesting in Nestle’s post was her explanation of two very different ways of looking at research into nutritional supplements — both of which rely on a collection of “true” statements, but reach opposite conclusions:

For example, on the need for supplements, a belief-based approach rests on:

• Diets do not always follow dietary recommendations.
• Foods grown on depleted soils lack essential nutrients.
• Pollution and stressful living conditions increase nutrient requirements.
• Cooking destroys essential nutrients.
• Nutrient-related physiological functions decline with age.

A science-based approach considers:

• Food is sufficient to meet nutrient needs.
• Foods provide nutrients and other valuable substances not present in supplements.
• People who take supplements are better educated and wealthier: they are healthier whether or not they take supplements.

I’m not sure I quite agree with her labels (“belief-based” and “science-based”), but I definitely see these patterns of thinking in discussions of pretty much all areas of health and exercise research. The first set of statements makes a strong case that it’s plausible that supplements could improve health — but it leaves out the final step, which is to show that they do improve health. Similarly, the second set of statements explains why we shouldn’t be surprised if supplements don’t improve health, but doesn’t prove it. So to me, neither of these two approaches is satisfying — because the debate should be settled empirically.

Of course, research is complicated, and in many health debates it’s difficult to agree on what constitutes empirical evidence. That’s less and less true in the case of vitamin supplements, though. Study after study fails to find any benefits, so the hypotheses of the “belief-based” approach seem emptier and emptier to me.

THANK YOU FOR VISITING SWEATSCIENCE.COM!

As of September 2017, new Sweat Science columns are being published at www.outsideonline.com/sweatscience. Check out my bestselling new book on the science of endurance, ENDURE: Mind, Body, and the Curiously Elastic Limits of Human Performance, published in February 2018 with a foreword by Malcolm Gladwell.

- Alex Hutchinson (@sweatscience)

***

Yesterday, I participated in a live chat previewing next weekend’s Scotiabank Toronto Waterfront Marathon. Among the participants were elite marathoners Reid Coolsaet, Dylan Wykes and Brandon Laan, who answered lots of questions about diet, warm-up, tapering and things like that. The most interesting nugget for me was some practical info about how to use beet juice: while I’ve blogged numerous times about the studies showing that beet juice provides a significant endurance boost, lab studies are very different from on-the-ground experience.

The most recent lab study used 500 mL of beet juice 2.5 hours before a time trial. But here’s what Reid had to say:

ReidCoolsaet: 500ml the day before. Anything the morning of upsets the stomach too much.

DylanW: Trent Stellingwerf has a protocol for 500ml in the 3 days before and 250ml morning of.