Category Archives: Disease Prevention

Healthy or Hype? Turmeric

Turmeric seems to be everywhere these days. This signature spice that lends curries and mustards their distinct colour is now popping up in unlikely foods and beverages like golden spice lattes, hot chocolate, and even sodas.

And you can count on more foods adopting turmeric’s characteristic yellow-orange hue, as the turmeric food trend is a strong one. A recent Google food trend analysis ranks turmeric as the number 1 rising star, as interest in turmeric has grown significantly in a short period.

Source: Google internal data, August 2015-February 2016, United States
Source: Google internal data, August 2015-February 2016, United States

The Internet is a go-to source for information about food and health. But teasing out the evidence-based information from the hype is becoming increasingly more difficult.  Is the turmeric trend supported by the body of scientific evidence?

What Is Turmeric?

Turmeric and Turmeric powder on white background

Turmeric comes from the thick root of the turmeric plant: it looks a bit like a small ginger root, and cooks prepare it in a similar way to add a subtle earthy flavour and bright colour to dishes.  If you are new to cooking with turmeric, be aware that turmeric can stain hands, clothes, and even cooking utensils bright yellow orange (historically turmeric was a popular dye, and some use it as a dye today).   Most people are more familiar with turmeric ground to a golden powder, which is available in the spice isle of most grocery stores.

Health Claims

Recognized as an ancient home remedy in Asia, and commonplace in Ayurvedic and Chinese medicine, many believe that turmeric has medicinal properties.  A quick search reveals turmeric as a “cure-all.” The claims for turmeric’s healing properties are wide ranging — from improving cognitive function, cardiovascular function, and weight loss to fighting cancer, Alzheimer’s disease, diabetes, arthritis, headaches, depression, digestive diseases, the common cold, and many more health conditions.  No wonder people are sprinkling turmeric on everything. . . (whether it tastes good or not).  Does this sound too good to be true?


A large body of research has looked into turmeric and health, focusing on curcumin, a polyphenol compound thought to be responsible for turmeric’s potential therapeutic effects. Curcumin makes up only about 3-5% of turmeric.

Curcumin, the potential health-promoting compound, makes up only about 3-5% of turmeric
Curcumin is the potential health-promoting compound in turmeric

Preclinical studies suggested that curcumin’s anti-inflammatory action might help prevent or treat various chronic diseases.  Though promising, it is important to categorize this research as preliminary or hypothesis generating, as much of it is “in vitro” (conducted in test tubes) or in animals. Researchers have studied curcumin in humans, but results have been inconclusive. Also, best to interpret this research with caution as most studies had a small number of participants, short durations, and many did not compare curcumin to a placebo. Though we shouldn’t generalize conclusions from these small-scale studies, their findings can inform larger scale trials.

Another issue with research in humans is that the body doesn’t absorb regular curcumin very well:  you can consume a lot of it, but very little reaches the blood or tissues where it can have a clinical effect.  Research shows that rodents absorb little (<1%) of the curcumin they consume. However, one line of research is investigating ways to improve absorption: for example, some studies suggest that black pepper boosts the bioavailability of curcumin.

So, turmeric contains <5% of curcumin, and most of this tiny amount isn’t bioavailable . . . why are so many stretching the culinary uses of this standard curry spice to desserts and convincing themselves that turmeric flavoured smoothies “taste good,” or are even “good for you?”Turmeric Smoothie Healthy

It’s too easy to be persuaded of turmeric’s potential healing powers. Those championing turmeric’s benefits are citing individual studies without proper scientific context.  Critically evaluating the available research is a challenge and requires substantial expertise. Luckily, a new comprehensive review published in January 2017 has done just that. Investigators at the University of Minnesota reviewed the evidence for curcumin, which included thousands of studies and over 120 clinical trials.  The authors raise important questions about the research and comment that curcumin’s health benefits are “much ado about nothing.”

There is no rigorous human study (double-blinded, placebo controlled clinical trial) showing benefit to turmeric.  Another serious problem overlooked by many is that curcumin’s chemical structure is unstable and can produce “false hits” in studies – i.e., showing that it is acting on a disease-causing protein, when it really isn’t.

What about Curcumin Supplements?

Are concentrated supplements of turmeric’s potential beneficial compound (curcumin) a good choice?  It seems many North Americans think so, as the market for curcumin is large (US$20 million in 2014) and growing.  And marketing by the likes of Dr Oz, Dr Hyman, Dr Mercola, or the Food Babe always persuades many. Curcumin supplements are likely a waste of money, as the recent comprehensive research review shows that they lack sufficient evidence of efficacy.Curumin Supplements Scientific Evidence

In general, you should be wary of all dietary supplements and their claims. The supplement industry is unregulated (which means questionable dosage, efficacy, and safety), but clever marketing manages to persuade many.

Bottom Line

Although many studies have investigated turmeric/curcumin, and some have shown promise, at this point these findings aren’t good enough evidence to suggest that consuming turmeric improves any health condition.  It’s important to consider the preliminary nature of the research and recent review questioning of curcumin’s biological activity. Turmeric is certainly not a cure-all panacea as some have touted.  More research may help uncover specific benefits to curcumin or other compounds in turmeric.

Typical North Indian spicy dish or cuisine called Chana Masala
Using turmeric in healthful dishes is a great idea!

But cooking with spices like turmeric is a great idea.  These plant-based seasonings can flavour food deliciously without the need for excess salt or fat.  And looking for recipes featuring turmeric may help you cook more and inspire you to prepare healthful dishes.  But even if effective, turmeric is a small-player for promoting health and preventing disease: better to focus efforts on eating a good diet, maintaining a healthy weight, and getting enough physical activity, measures that have proven benefits for health and well-being.

Healthy or Hype Series

More Healthy or Hype Resources at this link.

Healthy Or Hype General

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Fats vs Carbs: Clarifying Conspiracies, Controversies, and Confusion

Are you confused about how much fat you should eat? You have good reason! Many journalists and “internet experts” skillfully weave convincing stories about a large body of research.  We are often told to ignore academic experts and decades of nutrition research. What’s going on here?

A recent example is journalist Ian Leslie’s “The Sugar Conspiracy.” This was indeed a good story and quite persuasive.  Leslie provides a historical account of the research on the role of fat intake and heart disease. He states that the current recommendations of nutrition experts are wrong, and explains that nutrition researchers are biased and discount studies that don’t fit with their thinking.

Leslie has many convincing arguments, relying heavily on work of popular journalists Gary Taubes (Good Calories Bad CaloriesWhy We Get Fat) and Nina Teicholz (Big Fat Surprise), but he ignores a large body of evidence that would support any counter-arguments. Is he, and other sugar conspiracy proponents, guilty of the biased thinking for which they accuse nutrition researchers?

I’ll will examine Leslie’s arguments below, and summarize the following topics to help you understand the current nutrition debates.

John Yudkin vs. Ancel Key’s: Does Fat or Sugar Cause Heart Disease?

Leslie provides a fascinating account of how in the 1970’s, prominent nutrition researchers ridiculed the work and destroyed the reputation of a scientist (John Yudkin) who proposed that sugar was responsible for heart disease, diabetes, and obesity. Good story material for sure – bad guys, a good guy, and a conspiracy.

Did this really happen?  A nutrition scientist has scrutinized Leslie’s account of the story and provides an evidenced-based interpretation of Ancel Key’s research here. (Spoiler alert: Not really). Have a look! You’ll also figure out how to interpret the graph below: 

Ancel Keys Seven Countries Study
Ancel Keys Seven Countries Study

Does the research of good guy John Yudkin stand up to scrutiny? Kevin Klatt has reviewed his research here, and concludes that “there were significant limitations of Yudkin’s work and of the hypotheses surrounding sugar at the time.”

Did Americans Get Fat Because of Dietary Guidelines?

Scientists have to reckon with the fact that the obesity epidemic basically began with the first dietary guidelines. You can’t look at that and not think we’ve done something terribly wrong” – Nina Teicholz

O.K., the first set of guidelines weren’t perfect. But, did they cause the obesity epidemic? Maintaining an ideal weight is critical to good health, and featured prominently in Guideline #2.  Only 2/7 guidelines relate to Teicholz’s concerns (#3 and #4 to limit fat and eat adequate starch), but even then they emphasized whole foods. And don’t miss guideline #5 (I think Nina may have) – Avoid Too Much Sugar.

1980 Dietary Guidelines Fat Carbs

Contrary to stories of Leslie, Taubes, and others, these guidelines show there has been longstanding and prominent advice to limit sugar and refined carbohydrates. And, as I wrote in this article, contrary to what Teicholz, Leslie, and others allude most people did not follow the guidelines.

BIG Food = BIG Bodies

Did Americans Follow the Guidelines? While the 1980 Guidelines discouraged too much sugar and refined carbohydrates, Americans increased their intake of these foods: importantly, they also increased total calories and did not follow the low-fat recommendations, and they got fatter. Was eating this way an unintended consequence of the Guidelines to reduce fat intake? Doubtful.

The "Snackwell Effect" People eat more foods labeled as healthy/low fat
The “Snackwell Effect” People eat more of foods they believe to be healthy

Although nutrition experts emphasized vegetables, fruits, beans, and fiber-rich grains, the food industry latched onto “low fat,” and replaced fat in junk food with less healthful ingredients (more sugar/refined carbohydrates).  Food giants like Pepsico and Nabisco (Snackwell’s) produced low-fat cookies, chips, and other snacks and cleverly marketed it as healthy, because it was low in fat. And this was quite profitable.

The food industry has large budgets, powerful marketing, and their bottom line is money, not public health.  Consumer confusion and distrust in nutrition experts and evidence-based guidelines can actually be good for their bottom line. The food industry’s influence is far-reaching: consider also that they have a big say in Dietary Guidelines.  James Hamblin’s How Agriculture Controls Nutrition Guidelines is a good example of the industry sowing distrust in science.

So, clever food marketing and not nutrition experts convinced people that anything labeled “low fat” was healthy (even cookies . . . so why not eat two?). And it worked! Research now confirms that simply seeing the words “low fat” on a label encourages consumers to eat more.

Mammoth MuffinPortion sizes have increased dramatically and we eat more when served larger portions, another factor that has contributed to the obesity epidemic and chronic disease. Consider that an average restaurant meal contains almost a day’s worth of calories. The fact that we are simply eating too much shouldn’t be ignored or misconstrued while debating the merits of fats vs carbs in the diet.

Beyond the food industry, sedentary behavior, our obesogenic environment, and other influences have contributed to rising rates of obesity and preventable diseases. It is deceptive to blame these conditions on nutrition recommendations.

The 2015 Guidelines were generally well received by the nutrition community –  see a review by Marion Nestle and my interpretation, which I summarized in the graphic below. The scientific committee also recommended a goal of environmental sustainability, but lobbying power was strong and this was not included in the final guidelines.

How I interpreted the 2015 Dietary Guidelines Report

Ms. Teicholz launched a full-fledged campaign against the 2015 Guidelines.  Her criticisms are explained in this article.

Making Sense of Nutrition Science

Making dietary recommendations requires considerable expertise to interpret research from various fields, put it in context, and consider the cumulative scientific knowledge in the area. Many have criticized Teicholz’ ability to objectively critique research. According to Teicholz

“Americans have been the subjects of a vast, uncontrolled diet experiment with disastrous consequences.”

But how much weight should you give to individual studies? Just because a study was conducted in mice, or because a human study was “observational” doesn’t mean it should be discounted. And even the results of long-term well-designed clinical trials need to be carefully interpreted. (If you’re curious about how to weight various evidence, here’s a good primer).   Nutrition researchers do recognize the limitations of dietary data and implications for making evidence-based recommendations.  Importantly, experts often have strict methodologies for examining the scientific literature (see examples below). Unfortunately, the same can’t be said for many popular books and news articles, as is evident in a critical review of the Big Fat Surprise.

WCRF Colorectal Caner RiskEven Experts Disagree. . . But That’s O.K.! People complain that findings of research studies contradict each other. But, as explains epidemiologist Michael Marmot, who chaired the WHO World Cancer Research Fund’s examination of the evidence of diet and lifestyle influences on cancer, “That is the nature of science and a source of its strength.” For example, the World Cancer Research Fund review has a panel of expert scientists who examine and debate the scientific evidence to come up with recommendations to guide new research, prevention guidelines, and policy. They categorize the evidence as (1) convincing; (2) probable, or (3) substantial effect on risk unlikely. For example, this graphic shows how they categorized lifestyle risks on colorectal cancers.

The Scientific Committee for the Dietary Guidelines reports also follow a detailed protocol to interpret the literature, as explained here.

Do you think authors of newspaper articles and popular books or “internet experts” have such rigorous protocols or methodologies when they interpret the scientific literature?  It’s something to think about before you trust their stories.

Fats or Carbs?

What’s All the Fuss About FATS?

The 1980’s Guidelines advised avoiding too much fat or saturated fat. Now more evidence shows that certain fats are beneficial and should be part of a healthy eating pattern. These “healthy’ fats include monounsaturated and polyunsaturated fats found in nuts, seeds, fatty fish, and some vegetable oils. Trans fats – found primarily in processed foods – are considered unhealthy and should be avoided.

The role of saturated fat in health is a topic of much debate (and confusion!). Years of research have associated saturated fat with heart disease, some cancers, and diabetes. But more recent studies suggest that some types of fats may not be as harmful to some conditions as once thought. However, the evidence isn’t strong enough to disregard research showing saturated fat intake is harmful.

Red Meat And Poultry MED Public Domain Nci Vol 2402 150Are Meat and Butter Good for You? Many headlines interpret the emerging research on saturated fats as meaning that certain foods are good for us. While the role of saturated fat in heart disease needs more study, saturated fat intake is linked to other diseases. In terms of cancer, there is still considerable evidence linking high consumption of meat and/or processed meat with an increased risk of cancer mortality and an increased risk of incident cancers, particularly colorectal cancer.  Just because something is not as bad as once thought, doesn’t mean it’s beneficial, especially in copious amounts.  Replacing cookies with cheese might be a good swap, but replacing cookies with nuts is likely better.

CARBOHYDRATES Can Be Confusing, but That Doesn’t Make Them Bad

The type of carbohydrate you eat is likely more important than the amount. Carbohydrate critics tend to lump all carbohydrates into one category (somewhat like equating candy to broccoli). Vegetables, fruits, whole grains, and legumes are carbohydrate-rich foods, and affect the body differently than the refined and processed carbohydrates found in many popular foods.

Certain people may be more susceptible to the influences of carbohydrates on insulin (but again, eating lentils will influence the body differently than cake . . .). And how we metabolize carbohydrates has a lot to do with how active we are: though some studies do account for physical activity, even those participants categorized as “active” do not move much.

Kenyan Runners-Berlin_marathon_2012The world’s fastest distance runners have very high carbohydrate diets (about 75% carbs for Kenyans and 65% carbs for Ethiopians): and good evidence shows carbs are the preferred fuel for endurance athletes. New research recommends tailoring carbohydrate consumption to activity intensity and duration.  Some athletes seem keen to try High Fat Low Carb (HFLC) diets, despite the fact that carb restriction compromises the effectiveness of high intensity interval training and no evidence shows performance benefits.  The research is quite limited: an expert in this area, Louise Burke, provides a good evidence-based summary of the state of research on HFLC diets for athletes here.

Dietary Patterns Matter More than Nutrients

Mediterranean Diet FoodsExperts agree that it’s critical to consider the overall dietary pattern: eating less saturated fat won’t be helpful if the rest of your diet is full of highly processed foods. Though there are many healthy ways to eat (low carb and low fat), a large body of research shows that the most disease-protective dietary patterns are Mediterranean, DASH (Dietary Approaches to Stop Hypertension), or patterns assigned by studies as “Prudent” “High Quality” or “Healthy Eating” – they all contain healthful carbohydrates.

Examining the Credibility of Two Popular Anti-Carb Crusaders

Nina Teicholz and Gary Taubes are journalists with a disturbing degree of influence.  Should we be trusting them to interpret nutrition research?

Nina Teicholz

Big Fat Surprise “Painstakingly Researched?” While Leslie calls Teicholz’s book “painstakingly researched,” most evidence-based reviews show that Teicholz lacks the appropriate nutrition expertise to critique studies and put decades of research in context.  Many experts question her credibility and you should too.

Here is a detailed scientific critique that fact checks Teicholz’s text that outlines the many errors and biases (see The Big Fat Surprise: A Critical Review (Part 1; Part 2). Here are a few examples:

Big Fat Surprise Critique

Big Fat Surprise Critique Atkins 2

Gary Taubes

Gary Taubes argues that the main cause of obesity is eating too many carbohydrates. Many talk about the insulin-carbohydrate hypothesis of obesity as if it is fact. In reality, numerous studies don’t support this hypothesis. Obesity researcher Stephan Guyenet does a nice job explaining the insulin-carbohydrate hypothesis and outlines why you should question this reasoning.

The latest study to refute this hypothesis, published in Cell Metabolism, showed that for the same number of calories, a low-fat diet was better than a low-carb diet to lose body fat.  This was a “feeding study” – one of the most rigorous forms of studies that I summarize below:

Study participants received two diets in random order (a low-carb diet and low-fat diet) and spent part of the study in a “metabolic chamber” that captured all the air they inhaled and exhaled. Urine and body gases collected allowed researchers to determine the number of calories participants were burning and whether those calories came from carbohydrates, fat, or protein. Calories were restricted, so, as expected, participants lost weight and body fat on both diets. The low-fat diet seemed to have a metabolic advantage, and the low-carb diet slowed metabolism. A low-fat diet didn’t slow metabolism, and had increased fat burning and fat loss compared to the low-carb diet.

Do these results mean that “low-fat diets are best to lose fat” or “low-carb diets don’t work”? No, although this type of interpretation is common. The study authors caution that they conducted the research to better understand metabolism and energy balance, and not to form the basis of dietary recommendations. Here’s a good interview with the lead author explaining the study results, and if you’re interested in how this study relates to the carbohydrate-insulin hypothesis of obesity, obesity researcher Stephan Guyenet explains that here.

The insulin-carbohydrate hypothesis is an important theme in Taube’s anti-carb campaign and his books “Good Calories/Bad Calories” (you’ll find an excellent critical review here) and “Why We Get Fat.”  Obesity expert Yoni Freedhoff provides an excellent and detailed review of the book.  Among many other criticisms . . .

Taubes seems to have decided to abandon journalistic and scientific integrity in place of observational data, straw men and logical fallacy.”

“Taubes doesn’t just rely on non-scientific argument, he also appears to be comfortable in ascribing his beliefs to other people and to omitting facts when it’s convenient.”

Bottom Line

Should we trust the work of nutrition scientists? Critics claim that their diet recommendations led us to eat more sugar and refined carbohydrates, but this is not true.  On the contrary, the first recommendations issued in 1980 recommended limiting sugar and refined carbohydrates.  Obesity is a complex problem and it does not have a single cause.  Put simply, people eat too much, likely due to a variety of influences, including the food industry, sedentary behavior, and our obesogenic society. Understanding the multiple factors that influence obesity and preventable chronic diseases is critical, and undermining the public trust in nutrition research is not helping progress.

Some Key Points:

  • Nutrition science is difficult to conduct and interpretation can be complicated. Experts in the field are the best ones to interpret this research, not clearly biased journalists
  • Conspiracies make for a good story, but typically don’t represent good science
  • Nutrition experts never recommended increasing sugar intake or intake of refined carbohydrates, and it is doubtful that this was a direct consequence of nutrition guidelines
  • Food industry marketing is more persuasive than the advice of nutrition scientists


Photo of Kenyan runners in Berlin Marathon By Dirk Ingo Franke (Own work) CC BY 3.0  via Wikimedia Commons

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An Athlete’s Guide to Staying Healthy During Cold and Flu Season

Marit Bjørgen on her way to Olympic gold on the 15 km pursuit in Vancouver 2010.Photo: Bjarte Hetland / Wikimedia
Marit Bjørgen skiing to Olympic gold at the Vancouver Olympics.Photo: Bjarte Hetland / Wikimedia

The Norwegian team fought off more than their competitors at the Vancouver Olympics: following guidelines developed by their medical team after disappointing results at the Turin Olympics, they managed to fight off viruses at an impressive rate: only 5% of athletes got sick (compared to 17% in Turin) and just 4 missed an event because of illness (compared to 8 in Turin).

Illness can have far reaching effects among athletes if it strikes during an important competition or compromises training.  A mild infection like a cold that wouldn’t cause absenteeism in the general public can influence an athlete’s training and performance. Also, circumstances like travel to races and close contact with teammates can predispose athletes to illness. Upper respiratory tract infections (colds, coughs, flu, sinusitis, throat and ear infections) are some of the most common illnesses reported.

Although generally physical activity strengthens the immune system, high performance athletes may be more susceptible to infection at certain times, especially after intense or prolonged training sessions or during a heavy training load. After hard training, researchers have observed a decreased immune function in athletes, meaning that conditions are ripe for viral illnesses to take hold: these changes include increased cortisol levels, and increases in substances that could negatively impact white blood cell function (white blood cells help protect your body from infectious diseases).

Strengthen Your Immune System

But all sickness isn’t inevitable. Your first and best defense should be to maintain a strong immune system that is primed to fight off the germs, viruses, and other invaders that most of us are constantly exposed to.

Your immune system is not one entity, but an amazing interconnected network that includes cells, organs, and molecules that work together to protect you from colds, flu, and other ailments. The system is so complex that many factors can influence how it performs, including things that you can control, like your training, lifestyle habits, and nutrition.

Do you want your immune system to perform at its best? Here are some tips.

Get Enough Sleep

Woman SleepingSleep gives your body a chance to restore and repair itself. Sleep is also critical to many aspects of your mental, physical, and emotional health. Unfortunately, many athletes sacrifice the sleep they desperately need to squeeze more into each day.

Lack of sleep makes it harder for your immune system to do its job: during sleep, your body produces infection-fighting antibodies and protective “cytokines,” proteins that orchestrate your body’s response to infection and inflammation. Studies suggest that lack of sleep affects the ability to process carbohydrates, manage stress, fight infection, and regulate hormones (and importantly for athletes – it also hinders coordination, reflexes, and the ability to learn a new skill). Sleep deprivation can also reduce the effectiveness of flu vaccines.

People who don’t get enough sleep are more susceptible to getting sick after exposure to a virus. In fact, a recent study found that too little sleep can quadruple your risk for colds. Researchers exposed individuals to a cold virus, and found that those who slept less than 6 hours a night were 4.5 times more likely to catch a cold than those who slept more than 7 hours a night. The influence of sleep on colds was far greater than all other factors measured (which included age, stress, race, education, income). Don’t assume that 7 hours is an optimal amount of sleep based on this study (which looked at non-athletes); athletes generally need more sleep than the general population.

If you want to keep colds, flu, and bacterial infections at bay, prioritize sleep!

Practice Good Sports Nutrition

eload+clif bottleMany athletes neglect the importance of sports nutrition. This takes planning and a bit of time, but is definitely worth the effort. What you eat before workouts, during workouts, and after workouts not only supports your athletic endeavors, but can keep your immune system strong. One area that I see many athletes neglecting is consuming carbohydrates during long or intense training sessions, or coming to training sessions underfueled.

Athletes who don’t consume sufficient carbohydrates during intense or long training sessions might be decreasing their ability to fight off infections. Carbohydrates help maintain blood glucose concentration and limit metabolic stress: this study found that carbohydrate consumption during exercise was associated with lower stress hormones (cortisol and adrenaline) and reduced symptoms of overreaching, and another study found that exercising in a glycogen (stored carbohydrate) depleted state negatively influenced stress hormones. This article updates the latest recommendations for carbohydrate intake during exercise.

Eat a Healthy Diet

Mediterranean Diet FoodsAthletes should consume a nutrient-rich diet with adequate calories to support their activities and the vitamins and minerals necessary for good health. A dietary pattern that has been found to prevent chronic disease is also your best bet to fight off infectious diseases. Focus on vegetables and fruits, legumes, whole grains, lean proteins, and healthy fats while limiting processed foods, refined grains, and sugars.

Sugar intake can be confusing for athletes, because during workouts sugar is often your body’s fuel of choice for optimal performance. The trick is to save these sweet foods for when you need them during intense or long bouts of activity and when your body processes them to help you move, and limit them at other times.

What About Supplements?

supplements (640x482)In general, there is no convincing evidence to suggest that supplements boost immunity or prevent colds in healthy individuals, although they may help malnourished or some individuals deficient in critical nutrients.

Here is the the latest research on popular cold and flu supplements . . .

Vitamin C.  Despite being disproven by countless studies, many people believe high doses of Vitamin C will help prevent the common cold.  Some inconsistent evidence suggests that low-dose (250 mg – 1000 mg/day) supplementation with vitamin C might reduce the duration of a cold, and 5 studies in people exposed to severe physical exercise (including marathon runners and skiers) suggest that vitamin C might cut the risk of getting a cold in half (though 2 studies in competitive swimmers and marine recruits showed no effect).

Zinc. High doses of zinc acetate may reduce the duration of a cold, according to a recent analysis of three clinical trials. But zinc has potential side effects so don’t take for over a week, or as a cold-preventative.

Cold-FX  boasts many questionable claims, and there’s no evidence of benefit at symptom onset (and very weak evidence as a cold preventative).

“Immune boosting supplements” are a waste of money. And you may see lists of “immune-boosting” foods, but your best bet is to consume a healthy diet that includes a variety of fruits and vegetables.  In case you’re compelled to take Vitamin C based on the research noted above, here’s a list of foods rich in vitamin C (and many other protective compounds).

It’s important to consider research showing that megadoses of certain vitamins can actually suppress the immune system; for example, zinc is important for immune function, but high dose supplements may actually suppress immune response.

Also, athletes should keep in mind the emerging evidence showing that antioxidant supplements might actually hurt performance by reducing the health-promoting effects of training.

Food Sources of Vitamin C

Maintain a Healthy Weight

Runner Athletics 659444 1280 PubdomainFat cells influence the immune system. While most people consider fat inert, scientists now view it as an endocrine or immune organ that secretes hormones and other substances that influence many of the body’s processes. Excess body fat promotes the production of inflammatory immune cells that predispose to illness and disease and a weaken the immune system’s response to infections. So if you are overweight losing weight can improve immune function.

But inadequate body fat stores are problematic as well, and this could be a problem for athletes focused on becoming too lean.  Some fat is essential for a healthy body and immune system, and too little body fat can promote illness, increase susceptibility to colds and other viruses, and lead to immune system abnormalities.  Also, athletes should avoid rapid weight loss or severe calorie restriction as it compromises performance, health, and increases susceptibility to infections.

Respect Rest and Recovery Days

Sportlog CommentsIntense training is necessary to improve, but without adequate recovery built into a training program intense or excessive training can lead to a compromised immune system and decreased performance. Athletes react differently to training loads, so adjust your training or talk to your coach if you’re feeling unusually tired.

It’s a good idea to keep a detailed training log where, in addition to noting workout specifics, you can keep track of your sleep and fatigue levels. While some fatigue is expected after hard weeks or hard workouts, prolonged or unusual periods of fatigue are a sign that you need some time off.

Get the Flu Shot

Even healthy people can get pretty sick from influenza and spread it to others. Some experts believe athletes might be at higher risk of becoming infected if they have a high training load that compromises their immunity. And if infected with the flu, athletes may be at higher risk for complications like myocarditis.

A seasonal flu shot will help you develop antibodies against the viruses contained in the vaccine, greatly reducing your chance of getting infected with the flu. If you do get infected, it will reduce the severity of the illness. Importantly, protecting yourself from flu will also help protect those around you who may be more vulnerable  if they become infected (i.e., older people, those with compromised immune systems).

Time it Right. Elite athletes may have concerns about the timing of the flu shot and other vaccinations. This recent article outlines vaccination guidelines for elite athletes. It is a great resource and discusses vaccines recommended for athletes, and optimal timing to minimize interference with training and racing, and other issues specific to athletes.

Learn How to Respond to Stress

stress woman study homeworkBeyond the stress of intense exercise sessions, athletes may have stress related to school work/exams, job responsibilities, family obligations, and social interactions.

High academic stress can increase illness and injuries in athletes. Athletes are more than three times more likely to get injured during times of high academic stress compared to periods of low academic stress, according to a recent study by researchers at the University of Missouri.

Strategies to help cope with stress. Avoiding stressful situations isn’t always possible or practical. In fact, it’s likely how we respond to stress and not the stressor itself that contributes to illness. One study found that collegiate athletes (rowers) assigned to a group that learned strategies to cope with stress (Cognitive Behavioral Stress Management – CBSM) experienced significant reductions in the number of illness and injury days and reported half the number of health services visits compared to athletes who didn’t learn these strategies. (You can learn more about CBSM strategies in this lecture).

Mindfulness training is an additional strategy that is gaining popularity among athletes.  A study of elite junior athletes in Norway found that 12 weeks of mindfulness training had a positive impact on the athletes’ recovery and prevention of burnout, and a study in BMX riders found that a 7-week mindfulness training course improved several measures of self-awareness and stress response.

It might be helpful to keep in mind that stress isn’t necessarily a bad thing. As athletes, stress allows us to get stronger, fitter, and faster: hard workouts stress our body’s systems and they respond by adapting to handle the stress. Mental stresses allow us to figure things out, become more resilient, and learn to adapt to difficult situations.

That said, sometimes life throws you more stressors than you are primed to deal with. Try to anticipate periods of added stress (e.g., exam period) and adjust your workouts accordingly.

Don’t worry too much . . . Worrying is a form of stress and can affect health —  and that includes worrying too much about getting sick!  At least you can put the fears of sickness caused by airplane air, germs in gyms, and necessity of wearing face masks aside, according to UC Berkeley Wellness.

Limit the Invaders

While a strong immune system will improve your odds of staying healthy, you can also reduce your risk of infection by limiting your exposure to cold and flu causing germs.


Washing HandsHandwashing is an effective way to reduce the risk of infections. Many viruses are easily spread by direct contact, and unwashed hands are a terrific vehicle for germs. Your eyes, nose, and mouth are the route that most cold and flu viruses enter your body, and most people touch these areas many times throughout the day, often without realizing it.

So keep those hands away from your face, and wash them, especially after being in contact with someone who has a cold and other obvious times (e.g., preparing food, after using the toilet, playing with pets, etc.).

Most people could use a refresher in handwashing: a recent study found that only 5% of people wash hands the right way.

Here’s how to do it right:

  • Wash all surfaces of your hands with plain soap and hot water for about 20 seconds (about the time it takes to sing Happy Birthday twice – or if you prefer One Republic check out the video below!). Handwashing reduces the risk of getting sick by creating a slippery environment that causes microorganisms to slip off the hands.
  • Use a hand sanitizer (alcohol gels and wipes with at least 60% alcohol) when you don’t have access to soap and water. (Generally handwashing is preferable and just as effective at reducing the spread of germs).
  • Skip antibacterial soaps and antiseptic products. Research shows they have no benefit over regular soap and water, can cause skin irritation, and promote drug-resistant bacteria.

Limit exposure

Keep your distance and limit your exposure to infected people, and be sure to wash your hands after coming into contact. If facilities are available, coaches might consider giving a sick athlete their own sleeping quarters.

I Got Sick! Now What?

  • Cold And Flu Blow NoseTry not to expose others. Limit contact with others, and cover your mouth and nose with a tissue when you cough or sneeze to prevent the spread of germs. If you don’t have a tissue cough or sneeze into your upper sleeve or elbow, not your hands.
  • Get plenty of sleep and stay hydrated. Warm liquids may feel soothing to a sore throat, ease congestion, and increase the flow of mucus.
  • Over the counter products won’t cure your cold but can help ease symptoms. Keep in mind that they aren’t without side effects: some can cause drowsiness or disrupt sleep. Also, some contain a stimulant (pseudoephedrine) that is banned during competition (WADA advises athletes to avoid pseudoephedrine-containing cold and flu products for several days in advance of competition).
  • Supplements. Although marketing efforts will lead you to think otherwise, the evidence that supplements, pharmaceuticals, or products will shorten the duration of your cold is nonexistent or weak.  Some evidence suggests that zinc lozenges taken at the first symptoms may help a cold (be sure not to take them for more than a week, or long-term in the hopes you’ll prevent a cold). Cold-FX is a popular remedy boasting questionable claims, but there’s no evidence of benefit at symptom onset (and very weak evidence as a cold preventative). Sorry if I’ve ruined any placebo effect these supplements might have!
  • If you suspect you have the flu see your doctor. Ask about antiviral drugs that can shorten the duration of the flu and possibly reduce its intensity.
  • Home Remedies. Gargling with salt water might ease cold symptoms, and this study suggested that regularly gargling with salt water decreased colds by 40%.

soupChicken soup for a cold? A handful of studies have looked into this folk remedy, but the benefits aren’t clear. In 1978, Mount Sinai researchers conducted a study and found that a classic chicken soup was more effective at fighting congestion than hot or cold water. A more recent study found that a traditional  “Grandma’s” chicken soup with onions, sweet potatoes, parsnips, turnips, carrots, celery, parsley, might ease cold symptoms, possibly due to mild anti-inflammatory effect (although researchers could not isolate which soup ingredients were protective). Generally the evidence for chicken soup helping colds is weak, but it seems that any nourishing hot soup might have some benefits, due to their nutrition-filled broth that rehydrates, easy feeding for a sore throat or poor appetite, or hot vapors to help clear nasal passages.

Should You Exercise When You’re Sick?

Runner Stretching SmallLow intensity exercise can sometimes be helpful, but high intensity workouts or long training sessions aren’t a good idea; let the severity of your symptoms and how you feel guide you.

Some exercise physiologists encourage low to moderate exercise, especially for head colds where symptoms are above the neck (runny noses and sneezing), but advise more caution for colds that produce fevers or chest congestion.

Although this hasn’t been studied extensively, research has found that exercising with a cold didn’t affect lung function or exercise capacity, cold symptoms, or recovery time, and this study (in mice) found that moderate exercise lessened flu symptoms in mice infected with the virus.

You might consider illness a good time to focus on other sports-related activities (stretching, recovery techniques, mental training) or activities that don’t elevate heart too much or require strenuous breathing (skills and technique training).

Bottom Line

Strengthening your immune system and limiting invaders will help keep you healthy. A bonus is that beyond reducing illness, many of these strategies (getting more sleep, eating a healthy diet, reducing stress) will benefit other areas of health and athletic performance.


Reviewed & updated October 24, 2016

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This Week in Food, Health, and Fitness

This week, read about how coffee drinkers live longer, anti-odor exercise apparel, how strong legs predict a healthier brain, the Mediterranean diet and breast cancer, healthful holiday baking, and a preview of Just Eat It: A Food Waste Story.

coffee_© Vincent Mo_LatteCoffee drinkers may live longer. Although many people believe that coffee drinking is a bad habit, a growing body of research is showing that coffee can be good for health.  A new study published this week in the journal Circulation adds to this evidence. Researchers from Harvard University studied long-term coffee-drinking habits (3 decades) in three large prospective cohorts that included 208,500 men and women. They found that coffee drinkers lived longer, and had a lower risk of heart disease and neurological conditions. Other research has linked coffee drinking to reduced risk of diabetes, several types of cancer, and neurological conditions including Parkinson’s, MS, and Alzheimer’s. A prospective study such as this can’t prove cause and effect, but given the large body of evidence that corroborates these findings, further research into coffee drinking is warranted. (WebMD reporting on Circulation, Nov. 2015).

What’s the deal with anti-odor exercise apparel? Some high-tech workout clothes have anti-odor properties derived from silver-based compounds and chemical treatments. Grist takes a look at the effectiveness and potential environmental impact of these compounds.  (Grist).

Powerful Female LegsMuscle fitness predicts cognitive aging The link between physical fitness and brain health is an exciting area of research, and this longitudinal study adds the body of literature showing that what’s good for the body is good for the brain.  Researchers studied 10-year health and fitness data of 162 female twin pairs, using leg power as an objective measure of fitness. Women with the most powerful legs 10 years earlier had better thinking and memory skills than their weaker counterparts, and brain scans revealed healthier brains in women with strong legs. (Gretchen Reynolds, reporting on Gerontology, Nov 2015).

nutsEating nuts can lower cardiovascular disease risk.  Nuts contain healthy fats that are associated with favorable blood lipid profiles.  In this meta-analyis, researchers looked at 61 studies that examined the effect of tree nuts on blood lipids (tree nuts include walnuts, pistachios, macadamia nuts, pecans, cashews, almonds, hazelnuts, and Brazil nuts).  They found that tree nut consumption was linked to blood markers associated with lower heart disease risk (lower total cholesterol, triglycerides, LDL cholesterol, and ApoB). The greatest effect was linked with consuming 60 grams of nuts or more daily (60 g nuts is equivalent to about 15 walnut halves). (American Journal of Clinical Nutrition).

Cheerios Protein Healthwashing.  Research shows that many people could benefit from eating more protein in the morning. Cheerios has a new cereal – Cheerios Protein – but don’t be fooled, since it is not a healthy breakfast option. It might be considered a dessert, as it has 17 times more sugar than regular Cheerios.  And although it advertises that it contains 11 grams of protein, 4 of those grams come from the milk. (Center for Science in the Public Interest).

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Why foods that make you fart can be a good thing. New research into the gut microbiome (the bacteria in your intestine) suggests that producing gas means that your body is hosting beneficial bacteria. Resistant starch appears to be a beneficial food component that offers cancer and disease protection. Beans and legumes are one of the best sources of resistant starch.

Mediterranean Diet FoodsMediterranean diet, olive oil & breast cancer risk.  Another study adds to the growing evidence that eating a Mediterranean-style diet helps prevent disease. In this study (Predimed), women eating a Mediterranean diet reduced post-menopausal breast cancer risk by 51% compared to women in a control group.  Karen Collins of the American Institute for Cancer research takes an in-depth look at this study, explaining how research typically characterizes Mediterranean-style diets by the amount of vegetables, fruits, legumes, nuts, whole grains, with olive oil as the primary source of added fat,  and limited red meats or processed meats. The Predimed study found that olive oil consumption offered additional protection against cancer.  Collins suggests that it’s possible that studies linking greater olive oil consumption with lower cancer risk may be “because olive oil use tends to go hand in hand with an overall healthy pattern that involves eating more vegetables and other healthful plant foods” and stressed that it’s important that increased olive oil consumption doesn’t increase overall calories, as being overweight is an established risk factor for breast cancer. (Karen Collins, reporting on JAMA Internal Medicine, Nov 2015.)

sugarsA day’s worth of sugar in a single good.  The current recommended sugar intake for average individuals is about 12.5 teaspoons of sugar daily (average individuals are unfortunately sedentary, which exacerbates the effects of sugar; if you’re active you can get away with eating more sugar). For an overall healthy diet, it’s a good idea to reduce sugar intake, especially when you’re not moving your muscles. This article shows surprising foods that have over 12 teaspoons of sugar . . . and most of them aren’t even desserts! (The Atlantic).

Pumpkin Spice Bread_Evan_small
Healthy Pumpkin Spice Bread

Healthful holiday baking.  I do believe it is possible to produce great-tasting baked goods that are healthier than the typical holiday fare.  Some smart ingredient substitutions can reduce the sugar, fat, and calories and add a bit of nutrition to traditionally empty calories. Leslie Beck offers some clever substitutions in Globe and Mail column (a year old, but still relevant!). Also check out the baked goods in my recipe section.

READ  Ginger Bars with Chocolate

Healthy Or Hype Gluten FreeNew in my Healthy or Hype Series: Gluten-Free Diets. There is certainly a lot of hype about gluten-free diets.  In terms of diet trends assessed by Google,  “gluten-free diet” searches have risen dramatically over the last 10 years.  Gluten-free/grain-free diet books remain bestsellers.  And along with the interest is a multi-million dollar industry catering to the growing demand for gluten-free products.  But will going gluten-free benefit your health?

Canadian filmmakers feast for 6 months on discarded food.  Did you know we are throwing out about 50% of food produced? Jen Rustemeyer and Grant Baldwin stopped grocery shopping and set a rule that they would only consume food in the trash (or destined to be thrown out). They document their experiment of eating discarded food in their documentary Just Eat It: A Food Waste Story. (NPR).

Be sure to check out their website, which has educational materials and more.  Here is the movie trailer:

Just Eat It – A food waste story (Official Trailer) from Grant Baldwin on Vimeo.








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