Fruits & Vegetables May Help Prevent Hip Fracture

During aging and in elderly populations it is very common for bone loss to place individuals at risk for one or more fractures. Mild loss of bone is refereed to as osteopenia, whereas severe loss of bone is known as osteoporosis. Bone fracture risk is higher for those with osteoporosis and a great deal of research is being conducted to diagnose, prevent, and treat fractures in the elderly. Nutrition can pay a role in age-related bone loss and a common recommendation is to make sure you are getting plenty of calcium since calcium is the major mineral building block of bone. This recommendation has resulted in many individuals taking calcium supplements. However supplements are often taken with no consideration to the quality and composition of regular foods being consumed. Perhaps these can have a protective effect if chosen wisely.

In a recent article by Byberg and others (2014) in the Journal of Bone and Mineral Research, fruit and vegetable intake was analyzed in men and women to determine if there were statistical associations between intake levels and incidence of hip fracture. The rationale was that daily intake of at least 5 servings of fruits and vegetables is associated with reduced risk of disease (e.g., diabetes, cardiovascular disease). Further, prior studies have indicated fruit and vegetable intake was associated with increased bone mineral density. Some studies also exist linking fruits and vegetables to reduced forearm fractures, but the specific foods and doses could not be linked to the reduction in fracture risk. Therefore, in the Byberg et. Al 2014 study, the authors sought to clarify the relationship between fruit and vegetable intake and hip fracture risk.

The Takehome: The study indicated that, in both men and women, low intakes of fruit and vegetables (less than 1 serving) were associated with increases of hip fracture compared to 3-5 servings. Over 5 servings of fruits and vegetables did not appear associated with any increased reduction in hip fracture. So, there appears to be a limit to the power fruits and vegetables; you can’t reduce your fracture risk to zero by increasing your intake beyond 5 servings a day. As with all questionnaire-based studies, this study is limited by the ability of the participants to accurately recall the details of their past eating habits. The study also doesn’t address the mechanism by which fruits and vegetables might protect against hip fractures, though the authors speculate it may be tied to the roles these foods might play in reducing oxidative stress and inflammation, and increasing intestinal calcium absorption. Nevertheless, the findings are of note given the study’s large sample size and detailed data set. How many servings of fruits and vegetables are you eating each day?

STUDY DETAILS:

The Experiment

  • Swedish men (40,644) and women (34,947) free of cancer and cardiovascular disease (age 45-83 years old) were studied.
  • Fruit and vegetable consumption was recorded based on surveys given to participants asking them how often, on average, they had consumed each food during the previous year.
  • Responses were converted to average daily intakes based on age and sex-specific portion sizes.
  • There were 14 vegetable entries tracked (carrot, beetroot, broccoli, cabbage, cauliflower, lettuce, onion, garlic, peas, pea soup, pepper, spinach, tomato, and “other” vegetables) and 5 fruit entries tracked (apple, banana, berry, orange/citrus, and “other” fruits)
  • The outcome measure was a participant’s first incidence of a hip fracture.
  • Information on prevalent diseases, body composition, size, medication, smoking and various other variables were incorporated in the statistical design as covariates.
  • Depending on the specific analysis used, 5 or between 3 and 5 servings of fruits and vegetables per day was used as the reference point.
  • Cox’s proportional hazards regression models were used for assessing the association between fruits and vegetables and hip fracture.

The Results

  • The was an inverse association between fruit and vegetable intake and hip fracture such that less than or equal to 1 serving a day was associated with an almost 50% increased rate of fracture, as compared to 3-5 servings per day.
  • Compared with 5 servings a day, lower intakes of fruits and vegetables were associated with higher rates of hip fracture.
  • Intakes above 5 servings per day did not appear associated with any increased benefit to hip fracture incidence.
  • There was no interaction between fruit and vegetable intake and possible co-variants like potassium, magnesium, calcium, or body mass index (BMI). So, at the very least, these factors were not underlying the observed fruit & vegetable association.

The Limitations:

  • Fruit and vegetable consumption was self-reported by the participants (not monitored by the investigators).
  • Only certain covariates (education, physical activity, smoking) were considered and other factors not considered may be contributing to the observed relationship between fruit and vegetable intake and reduced hip fracture incidence.
  • This study does not point to causation, only association between fruit & vegetable intake and reduced hip fracture incidence.
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5 Things Fitness Experts Wish You Would Stop Doing in the Gym

I was a guest contributor on a recent top.me article surveying fitness experts about what they would wish people would stop doing when they go to the gym. I weigh in on #3 and #4. You can read the article here.

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Movie Review – Forks Over Knives

One of the people I train suggested that I watch the movie Forks Over Knives as it is the basis for his, and many other individuals’ switch to a vegan lifestyle. For those that might be unaware, vegans consume foods that are plant-based and in no way derived from animals. I watched the movie last night and it was a very good example of the problems we face in objectively and fairly presenting science to the public. The upside is that this experience can be used as a great learning tool (by virtue of this posting) and it has now made me realize that movie and book reviews will be a great addition to this site. So without further ado, my review of Forks Over Knives.

SUMMARY: The science in this study is disappointing (see Movie Details below). Some claims are dated and no longer valid, key experimental details of other studies are omitted and appear to have been framed just to fit the theme of the movie. But all of this aside, the major message of the movie – that a whole-food, plant based diet is healthiest – simply cannot be supported. Overall the movie spends a large amount of time on personal stories of how a plant-based diet improved the health of many people. But the diets of these individuals were typical western diets full of excessive calories, dairy, and refined carbohydrates. For sure the movie does a good job of showing you that the plant-based diet is better than the traditional western one, but that hard line is not maintained. The movie strays into claiming meat and dairy are bad. Perhaps they are (there is more and more evidence to support that diary is not the best, at least for adults), but the movie can’t separate them out. The movie ends with what sounds like a nice synopsis: “You have two choices. You can eat yourself into poor health and early death or you can eat yourself into good health and a long healthy life…and that road is on a plant-centered dietary pattern.” Unfortunately this claim can’t be substantiated. There are too many diet permutations out there right now and these must be considered. For example, to make this claim you would have to at the very least compare whole food, plant-based diets to whole food, paleo diets. Paleo diets remove dairy, grains, and refined carbohydrates, while including meat. I give this movie a C.

MOVIE DETAILS:

Background: The movie came out in 2011, so it is several years old. The premise is that a whole food, plant-based diet is the answer to preventing many, if not all, of the diet-related diseases and increased mortality rates seen over the past hundred years. Various individuals including scientists, doctors, and those who have tried the diet, were interviewed and give an array of information and personal experiences.

The Health Problem: Forks Over Knives sets the stage well in terms of highlighting the obesity epidemic and noting that western society’s consumption of meat, dairy, and refined carbohydrates has increased dramatically alongside a variety of diseases (such as cancer) and alongside increased mortality rates. But from this point on the movie lumps these three dietary components together (meat, dairy, refined carbohydrates). Scientists have a hard enough time with factors they didn’t consider, but here we have three known factors (some of which may be a problem, some of which might not be) being grouped together.

The Cholesterol Argument: The writers of the movie fall into a common trap of using the old dietary cholesterol (cholesterol you get in your food) literature as support for staying away from meat. The correlative studies of cholesterol and cardiovascular disease began in the 1960s and are hugely problematic. Gary Taubes does a great job of pulling apart all this literature in his books Good Calories, Bad Calories and Why We Get Fat. The science just doesn’t stand up to the test of time.

The Rodent Cancer Reports: The movie highlights a study where high levels of casein (a protein in milk) caused cancer in mice. But the cancer was in combination with Aflatoxin, a known carcinogenic mold toxin. An interaction such as this is hard and dangerous to interpret in terms of the effects of Aflatoxin and casein alone. The movie does note another study (in rats) where only casein levels were altered and the rats became susceptible to cancer and other systemic disruptions. This is a better study for making the case that dairy might be harmful, but again, it was performed in rats and only looked at one milk component. And of course, this only speaks to dairy, not to meat consumption.

Nutrients From Animals Fat Caused Cancer: The movie passingly notes that Dr. Campbell conducted many studies (presumably in animal model) that showed many nutrients in animal fats caused cancer. However, the movie does not indicate which ones, nor the context in which they were tested. For example, were these nutrients only found in animals, and not in plants?

The China Study: Arguably the pillar on which this movie rests is The China Study conducted by Dr. Campbell. This was a huge correlation study and I mean huge. 94,000 correlations between diet and disease were found. Of these around 9,000 were significant. This is quite a lot, but given the vast number of correlations that were considered, it is not surprising to find many significant results. The summary point made was that plant-based diets were correlated with lower disease occurrences and lower mortality rates. But here is where have to go back to the lumping I mentioned above. The study does not control for what could be a drop in meat, dairy, or refined carbohydrates. In fact the study didn’t measure these differences well at all. Gary Taubes was questioned about this study and you can read his response here. On major issue he hits on is how the study don’t control for carbohydrates and, thus, the plant-based individuals were being compared to individuals that had a higher sugar content in their diet. Thus, low sugar intake may very well have been the factor that lead to the better health in the plant-based groups.

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That Sugar Film

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.



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No, A Glass of Wine Doesn’t Equal 1 Hour of Exercise

Wine (Wikipedia)

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.

STUDY DETAILS:

The Experiment:

  • 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.

The Results:

  • 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.

The Limitations:

  • 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.
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Product Recommendation – This Pie is Nuts

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!

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Adult Milk Consumption – Too Much of a Good Thing?

Milk (Wikipedia)

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.

STUDY DETAILS:

The Experiment:

  • 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.

The Results:

  • 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.

The Limitations:

  • 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.
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What is a Virus?

Typical Bacteria (Wikipedia)

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.
 

Typical Virus (Wikipedia)

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.

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Pull-Ups or Chin-Ups?

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:


Pull-Up, Palms facing away (pronated)
Chin-Up, Palms facing you (supinated)

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.

STUDY DETAILS

The Experiment:

  • 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 Results:

  • 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 Limitations:

  • 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).
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Publication Bias – Null Results Are Rarely Published

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?

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