About 10 years ago Morgan Spurlock starred in the groundbreaking film Super Size Me where he ate only McDonald’s food for a month. Now, Australian TV actor and filmmaker Damon Gameau is taking a similar approach. He stars in That Sugar Film which will air in Australian cinemas in early 2015. In the movie he too alters his diet for a month, but this experiment has him eating a low-fat diet, which therefore is higher in sugar. What is interesting about this movie is that he tries to consume “healthy” low-fat foods. That is, he doesn’t dive into soda and candy. He chose a lot of foods that would appear healthy to a consumer because they are advertised as low in fat. The trailer below gives a hint of what the results were, including a truly impressive onset of fatty liver disease in only three weeks.
In this week’s post I return to my roots and highlight some new reporting that doesn’t quite do justice to the reality of a scientific study. It all began when I saw a Facebook link to an online article entitled “Drinking A Glass Of Red Wine Is The Same As Getting An HOUR OF EXERCISE, Says New Study and Our Wildest Dreams.” You can view the original Bustle.com web article here. But when you view it, you can see that it is actually citing another second-hand source (found here) with even less information. Both articles have very misleading titles. The articles note that the authors of the scientific study, Dolinsky et. al, 2012, have claimed an antioxidant compound in wine (resveratrol) can yield similar benefits to exercise. And yet the title of both articles suggests drinking wine was examined in the study. So, let’s directly examine the Dolinsky et. al study, which actually was published two years ago I might add (despite both web articles posting about the study within the past few months).
The Takehome: It’s possible that a glass of wine equals an hour of exercise, but the Dolinsky study didn’t ask that question, so such a claim has no basis in regards to this work. The study looked at one compound in wine (resveratrol) and found that treating rats with resveratrol results in a variety of physiological changes that are also found after exercising. While some “exercise effects” of resveratrol occurred when the compound was given to rats that were not exercise trained, the majority of the data in this study looks at the effects of resveratrol on exercise trained rats. As a result, the data in the paper make a stronger case for resveratrol improving aspects of health & fitness (insulin and glucose sensitivity, time to exhaustion, fat oxidation) in rats that were previously exercised trained. So, this study is more applicable to an athletic population, not a sedentary one. Still, the improvements noted are not entirely clear-cut. For example, although cardiac function was improved by resveratrol in several ways, it was not improved in one of the most sought after ways – cardiac output. The effects of exercise on the human body are vast and this study suggests resveratrol can duplicate some of them, but not all. And as for wine, we can only speculate.
- Male rats were used as a model for humans in this study.
- 4 g of resveratrol per kg body weight per day was administered to rats in their food.
- Initial exercise training was 60 minutes of daily, forced treadmill running (speed increased progressively during sessions) for 5 days/wk. Total duration of the training was 12 weeks.
- Exercise testing was performed using a series of forced treadmill running bouts to exhaustion. A control group of rats was handled similarly, but did not receive any exercise training.
- A variety of outcome measures were assessed in addition to time to exhaustion: Muscle force production, left ventricular wall stress, glucose and palmitate oxidation rates (from isolated heart tissue), glucose and insulin tolerance, gene expression analysis of isolated heart tissue.
- Rats supplemented with resveratrol had significant improvements (~25%) in time and distance to exhaustion whether they had exercise training or not.
- Comparing only the rats who had exercise training, those given resveratrol had increased exercise performances of around 20%.
- Muscle (tibialis anterior) twitch force was greater (~18%) in resveratrol treated rats who exercised compared to exercisers without resveratrol. A similar result was found in the soleus muscle (~58% increase in twitch force).
- Exercised rats given resveratrol had significanly improved left ventricular (blood) ejection fractions compared to those without resveratrol, but heart rate and cardiac output was unchanged.
- Insulin and glucose sensitivity were improved and oxygen consumption increased in exercised rats given resveratrol compared to those who were not.
- Analysis of excised (removed) heart tissue indicated resveratrol enhanced certain markers of fat oxidation/metabolism in exercise-trained rats.
- Male rats were used in this study and the results may not be applicable to male and female humans.
- Intact heart rate and cardiac output measurements were conducted under anesthesia.
- Cardiovascular measurements from excised heart tissue do not entirely match changes observed in the intact animals.
- Cardiovascular measurements from excised heart tissue indicated enhancements in only some markers of fat oxidation/metabolism; free fatty acid and cardiac triglyceride levels were not altered by resveratrol treatment.
My Product Recommendations section has expanded now with the addition of a new category of product, namely Baked Goods. The inaugural member of this section is a baking company known as This Pie is Nuts. They are a fledgling business serving only locally here in NYC, but I am really hoping things take off for them. They make a selection of individual squares of pies (see picture to the left) as well as 9 inch pies. What’s interesting is that they make their pie crusts entirely out of nuts. There is nothing processed in their pies and the pies are Certified Vegan, Certified Paleo and Gluten-Free. This is huge for me as I have little to no dairy or simple sugars in my diet. Although Paleo foods can be quite tasty, it’s often because large amounts of honey, agave or maple syrup are added. Not so with these pies, they have just the right amount of these natural sweeteners; they are just a tad sweet. So, if you’re in the NYC area check them out at the Bryant Park shops this Holiday Season and if not, keep your eye on them for when they can make it to your neck of the woods!
A friend posted an article from the Washington Post to my Facebook feed the other day. The article discussed a scientific study examining milk consumption, mortality and fracture risk. As web articles go, the Washington Post’s discussion of the scientific study was pretty good.
But, as a parent of a young girl, my friend asked what my thoughts were on the original Michaelsson et. al, 2014 study. It is ingrained in our culture that children should drink lots of milk growing up because it is a great source of calcium and calcium is essential for building strong bones during growth. Milk is also a good source of protein and carbohydrates – also important for growth. So, when an article like this comes along it can be a bit unnerving for parents who are trying to raise their kids in a healthy way. So, let’s examine the study in a bit more detail.
The Takehome: This study examined adult men and women and found that higher consumption of milk by both men and women was associated with higher mortality (death) rates. In women there was also an association with higher fracture rates. This is contrary to what one might expect about milk helping us build strong bones, but remember this study did not look at kids. These were adults from 39-79 years of age. The investigators suspected that the possible culprit in milk, though not tested directly in this study, is D-galactose. It’s a sugar that has been associated with aging effects, increases in oxidative stress, and shortened lifespan in animals. Oxidative stress and inflammation were measured in the patients of this study and levels generally did increase in association with greater milk consumption in adults, so this is definitely an avenue worth pursuing in future studies. Another interesting finding in this study is that the associations with death and fracture risk in women were less obvious if the women were largely eating cheese or other fermented milk products – highlighting that the form of diary intake may make a difference and that it may also be sex-specific. So, one should not take away form this article that milk is bad for growing children, only that excess consumption in aging adults may be problematic.
- 61,433 women and 45,339 men were enrolled in the study. Ages ranged from 39-79 years.
- Participants were given questionanaires to track milk consumption.
- Various follow-ups were made during subsequent years (e.g., 11 years, 20 years, etc.) where the investigators assessed the number of participants who died (mortality) or suffered a fracture.
- Markers of oxidative stress were also measured from urine and blood serum during follow-ups.
- The authors predicted that high consumption of milk would increase oxidative stress which in turn would increase mortality and fracture risk.
- Multivariate survival models were used to determine the association between milk consumption and time to mortality (death) or fracture.
- For women, a positive association between milk intake and total mortality as well as fracture (especial hip fracture) was found. In women this higher death rate association was observed for cardiovascular death, cancer death, and the aggregate of all causes of death lumped together.
- For men, there was also a positive association between milk intake and rate of death, but the level of risk was less pronounced than in women. Further, deaths appeared mainly associated with cardiovascular disease in men.
- There was no relationship found between milk intake and fracture rates in men.
- Consumption of cheese or fermented milk products were associated with lower mortality and fracture rates in women compared to women who drank milk. This relationship was largely absent for men.
- Milk intake was positively associated with oxidative stress marker 8-iso-PGF2alpha in both men and women, but only with inflammation marker Interleukin-6 in men.
- Milk consumption and lifestyle factors were tracked via questionnaires, so there is an inherent level of inaccuracy as participants are generally not as accurate as scientists would like.
- In the 20 year follow-up, clinical data on oxidative stress marker levels were not obtained for all surviving participants, only a sub-group, though statistical power appears to still be sufficient given the large sample size.
- The possible culprit behind the associations (D-galactose), was not quantified in this study, so the association is speculative at this point.
- The age-specific nature of this study and lack of control for ethnic background may limit how the study results can be applied to other groups.
With the recent Ebola outbreak in Africa, I’ve had a number of individuals question me as to what exactly a virus is. When I ask them what they think it is, they usually say a very small organism related to a bacteria. In actuality viruses are quite a bit different from bacteria and trying to understand the difference can be quite a task for those without a biology background. In this post I’m going to walk you through it by placing viruses in the larger context of life on Earth.
Most people are familiar with cells. These are the living building blocks of plants and animals. Cells are self-contained structures (due to their outer cell membrane). They take in nutrients from their surroundings and convert these into energy, store hereditary material (DNA), and are capable of duplicating themselves. The human body has trillions of cells, all working together to provide complex function and the ability for us to heal when injured. Cells can exists independently of each other and some of the smallest organisms are just that – single cells that have their own lives. They take in nutrients, create energy, and divide, creating more of themselves. The figure above and to the left shows an example of a single-celled bacteria. Bacteria are everywhere and we know that some can be very beneficial (the Escherichia coli in your gut) while others can pose health hazards (Bacillus anthracis which causes Anthrax).
It’s relatively easy to view bacteria as being “alive” since they, all by themselves, take in nutrients, convert nutrients to energy, store heritable material like DNA, and reproduce. Bacteria also make sense in the larger spectrum of life as they help the decomposition of matter (dead animals, plants, etc.) and they are also food for larger single-celled organisms and small crustaceans. These organisms are, in turn, food for larger organisms and the trend continues all the way up to humans which consume a wide variety of plants and animals. Bacteria are quite small (between 0.5 and 5 micrometers). Viruses, on the other hand, are 0.02 – 0.4 micrometers in size. So, viruses are generally smaller than bacteria and it’s natural to assume they fall below bacteria on the “food chain.” Perhaps bacteria feed on viruses and so on. However, the reality is somewhat different.
Viruses are not cells. They consist of heritable material (DNA or RNA) surrounded by a protein coat, which is in turn surrounded by an envelope of lipids (fats). A typical virus can be seen in the picture to the right. Left alone viruses cannot take in nutrients from their surroundings and convert them to energy, nor can they reproduce themselves. The gut reaction when people first hear this is…viruses aren’t alive? It’s actually generally accepted that viruses are alive because once they infect a host’s cells (or the host cell if the host is just one cell like a bacteria), they use the cell’s machinery (organelles) to generate energy and reproduce. Viruses can infect bacteria, plants, animals. Nothing is immune. A virus infects a cell and highjacks the the cell’s normal infrastructure for living in order to support a rapid reproduction of itself, which then results in the destruction of the host cell. For single-celled organisms, this kills them, for multicelled organisms like humans, it causes cell death in our bodies which we can sometimes recover from (a Cold) and other times have a very hard time recovering from (Ebola).
From an evolutionary perspective viruses are very confusing. We don’t really know how they arose. We also don’t really understand their “purpose.” It’s much easier to see the purpose of almost every other organism as they tend to do something constructive like generate oxygen, breakdown decaying matter, or at least, they are food for other organisms. You might look at humans and think, well we are somewhat of an exception as well. We don’t really have any predators and can certainly do more harm than good to an ecosystem if we aren’t careful. For a “circle of life” view you might think of viruses preying on humans, as they can certainly kill us, but it’s still a bit forced as viruses infect everything, not just humans, and nothing really preys on viruses to complete the cirlce. So, even today, viruses are still a bit of a mystery. They are exquisitely designed to infect other organisms and propagate themselves at extremely high rates/numbers. We know much more about viruses today compared to when they first came across our radar in the late 1800s, but there is clearly still much more to understand.
When I train my clients one of the questions I often get asked by them is, when performing a pull-up, does the grip (or orientation of the hands on the bar) matter? Specifically, they are asking the difference between having their palms facing away from them versus having their palms facing them. The palms facing away grip is known as a Pull-Up, whereas the palms facing you grip is known as a Chin-Up. You can see an example of each below as taken from Youdas et al., 2010:
There actually is a difference in the exercise depending on which grip you use to pull yourself over the bar. This difference has been known for a while now and to highlight it, I have chosen an older work – Youdas et al., 2010.
The Takehome: Using EMG and motion capture analysis the authors of this study showed that when you do a pull-up (palms facing away from you) your back muscles (specifically, infraspinatus and lower trapezius muscles) tend to have a greater activation. If you switch your grip for a chin-up (palms facing you), then your chest (pectoralis major) and arms (biceps brachii) are more maximally activated. When my clients are just getting started, I don’t have them worry about which grip they use. I let them choose whichever is most comfortable because, either way, they will be getting a good upper-body workout. However, for those more advanced in their training, this distinction can be important; you can choose your grip to focus more on developing the anterior (front) of your body with a chin-up or to focus more on developing the posterior (back) of your body with a pull-up. Assuming an individual doesn’t have any pre-existing muscle imbalances, mixing both grips into one’s training routine is a good way to be well-rounded.
- Electromyography (EMG) was used to measure motor unit activity within muscles.
- The authors compared the pull-up, chin-up and The PerfectPullup(TM) device, the latter of which I do not discuss.
- 7 muscles were examined with EMG – lower trapezius, latissimus dorsi, infraspinatus, erector spinae, pectoralis major, external oblique, and biceps brachii.
- Motion analysis was combined with EMG data to link muscle activation to specific parts of the exercises’ range of motion.
- 21 men and 4 women in their 20s were used in the study.
- The lower trapezius and infraspinatus had greater activation in the pull-up compared to the chin-up.
- The pectoralis major and biceps brachii had greater activation in the chin-up compared to the pull-up.
- Differences in elbow joint sagittal plane range of motion between chin-ups and pull-ups were statistically ambiguous.
- The participants (the study sample) were heavily biased towards men. It would have been better to have the study just use men since an equal mix of men and women was not possible.
- The finish position for each trial had the participant just reaching their nose above the bar. Pulling such that the entire chin was over the bar or so that the bar touched below the clavicle (chest), would have been more challenging and might have resulted in different muscle activation patters. It is interesting that they did not take this approach given that they did try to compare elbow joint sagittal plane range of motion (which turned out to be statistically ambiguous).
- The authors highlight some statistical differences in the text of their paper that do not match the indicators in the Figures of the paper (which may be a result of clerical error).
Publication bias is something that continually plagues science. It is most apparent in the types of data the get published. Data that is not positive (that did not prove the researchers’ hypothesis) is rarely published. Such “null result” data indicates that no effect was found or no difference exists (within the study’s design limitations of course). Part of the rationale behind this is, if you didn’t see an effect, there might still be one if you performed the experiment differently. Perhaps if you used a higher dose of drug, looked in a different age group, or used a different animal model, an effect would in fact be there. Allowing for this possibility, scientists don’t like to flood the literature with null results. But how big of an issue is this really? In a recent article from the journal Science, researchers examined this bias in the social sciences.
The authors followed 221 research projects and found:
- 96% of the experiments that produced positive results were then written up and submitted for publication.
- Nearly two thirds of the experiments that produced null results were simply filed away (not prepared or submitted for publication).
The fact that nearly 65% of null studies weren’t even written up is surprising. This represents a lot of time, money, and work that is not seeing the light of day. Many people feel that all results from all studies should be made available. This way a bigger picture can be formed, but also having this data available would help prevent other researchers from conducting the same experiment in duplication – wasting time and money only to get the same null results. In clinical drug trials the demand for a release of all data (in the form of a completed manuscript) has been the greatest as it would give doctors and patients more information from which to base opinions. For example, with just two successful positive trials showing an effect there is little reason to not use the drug. But humans are genetically very diverse and history has shown that over time many approved drugs ultimately show side-effects that were not anticipated. Currently, many experiments in animals with null results don’t have to be published at all and negative results in human clinical trials only need to have the simplest data set released to an NIH registry; researchers do not have to write the full human study up for publication. If instead the two successful trials were available, but so were 5 other experiments that showed no effect in different models (animals, humans) and different age groups. This might temper the decision of doctors and patients towards trying a new drug.
There is no simple answer to this problem of publication bias. Many researchers insist that null results should not be given the same weight as positive results and thus do not want the literature flooded with such studies. At the same time, studies with null results give valuable information. Many are now calling for a public database in which scientists can deposit their null results so that everyone can make better informed decisions going forward. What do you think? Should all results be written up and made available to the public?
If you haven’t checked out the Product Recommendations page, which had a soft launch several months ago, have a look now. Today is the official launch of the page which has been created in response to numerous requests from my readers. The page gives the rationale behind my offering this service, the initial two companies I am recommending, as well as instructions for submitting other candidates for the page. Let me know what you think!
from the National Review of Medicine
The human body contains numerous microorganisms (bacteria, funji, etc.) residing in locations such as the intestinal tract (gut), mouth, and skin. Many believe the number of of these microorganisms (microbes) exceeds the number of cells we have on our bodies. Some microbes are known to have an important beneficial role to human health (see my prior article for an example of what can happen to your digestion if you disrupt them), but for the vast majority, we don’t fully understand what role they have in human health.
Studies have indicated that gut bacteria are important for digestion, energy production and energy storage. In addition, studies have shown that gut bacteria can affect anti-oxidant production; anti-oxidants are compounds that protect against free-radical tissue damage which occurs, in part, from the pathways your body uses to obtain energy. Since exercise causes an increased demand for energy and this potentially increases free-radical tissue damage, it is possible that gut microbes are moderators of exercise performance through regulation of energy production and anti-oxidant activity. Using this line of thought, the authors of Hsu et al., 2014, in a recent article from the Journal of Strength and Conditioning Research, performed a study to examine the effect of intestinal bacteria on exercise performance.
The Takehome: This study had two main questions. The first was whether gut microbes affected exercise ability, specifically time to exhaustion in swimming mice. The second was whether they simultaneously affected anti-oxidant production, thereby linking the effect on exercise exhaustion to anti-oxidants. The study indicated that a normal disease free mouse (Specific Pathogen-Free) had the most swimming endurance and that if you use a mouse who has no normal gut microbes (Germ-Free) the endurance is notably worse. The third mouse group was “Germ-Free with added Bacteroides Fragilis” which is a “rescue” group. Here the investigators gave the Germ-Free mice one beneficial gut bacteria and, as expected, they had better endurance than Germ-Free, but not quite as much as the Specific-Pathogen free mice which had multiple types of gut microbes. Thus, endurance exercise appears linked to a healthy gut microbe population. The second story, trying to link this to anti-oxidants, was not as convincing. Some anti-oxidant levels were higher in the normal disease free mice (Specific Pathogen-Free), some were lower, and some were identical. That these levels were measured in different sites (blood, liver, etc.) also complicates the story. So, we must reserve judgement on the anti-oxidant effect, but the exercise effect is interesting. Would a similar effect be found if the mice were resistance trained (jumping, climbing)? This would make for an interesting follow-up study.
- 12 week male mice were used. Groups were “Specific Pathogen-Free” (no infectious microbes), “Germ-Free” (all microbes absent), or “Germ-Free with added Bacteroides Fragilis” (a beneficial gut microbe found in mice and humans).
- Exercise was administered to mice in the form of a swimming test which recorded time to exhaustion.
- 48 hours after the swimming test, organ measurements were taken and blood measurements were taken. This included general descriptive data as well as antioxidant activity in tissue and blood serum.
- All groups had identical body weights, but the proportion of liver, muscle and fat was higher in the Specific Pathogen-Free mice.
- Swimming time to exhaustion was different for all three groups with the Specific Pathogen-Free mice being able to swim the longest, Germ-Free being able to swim the shortest amount of time and the Germ-Free with added Bacteroides Fragilis being able to swim for an intermediate length of time.
- Germ-Free mice had the highest levels of uric acid and urea nitrogen in their blood.
- Germ-Free with added Bacteroides Fragilis had the lowest levels of total cholesterol and triglycerides in their blood.
- Antioxidant activity of glutathione peroxidase, and catalase in blood, was greatest in Specific Pathogen-Free mice.
- Antioxidant activity of superoxide dismutase in blood was lowest in Germ-Free with added Bacteroides Fragilis mice.
- This study was conducted in mice, so application to humans is limited.
- Mice where swam to exhaustion (near drowning) which is an extremely stressful form of exercise that may not translate to exercise that most humans would conduct to stay healthy.
- This study does not address the possible effects of resistance exercise.
- The decline in exercise ability from Specific Pathogen-Free mice to Germ-Free mice, which was then partially recovered using Germ-Free with added Bacteroides Fragilis mice does not match the anti-oxidant data. That is, although Germ-Free with added Bacteroides Fragilis mice were better swimmers than Germ-Free, they had either similar or lower anti-oxidant levels to Germ-Free mice, making the link between exercise and anti-oxidant levels weak at best.
In today’s video post, I talk about 5 tools everyone should own to assist in daily maintenance and recovery of their bodies – specifically their muscles, which can get very tight from non-deal lifestyle factors, sports, or training. Be sure to go to Science for Fitness’ YouTube channel and subscribe if you haven’t already.