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Calcium supplements and heart attacks: More data, more questions

Why take a drug, herb or any other supplement? It’s usually because we believe the substance will do something desirable, and that we’re doing more good than harm. To be truly rational we’d carefully evaluate the expected risks and benefits, estimate the overall odds of a good outcome, and then make a decision that would weigh these factors against any costs (if relevant) to make a conclusion about value for money. But having the best available information at the time we make a decision can still mean decisions turn out to be bad ones: It can be that all relevant data isn’t made available, or it can be that new, unexpected information emerges later to change our evaluation. (Donald Rumsfeld might call them “known unknowns.”)

As unknowns become knowns, risk and benefit perspectives change. Clinical trials give a hint, but don’t tell the full safety and efficacy story. Over time, and with wider use, the true risk-benefit perspective becomes more clear, especially when large databases can be used to study effects in large populations. Epidemiology can be a powerful tool for finding unexpected consequences of treatments. But epidemiologic studies can also frustrate because they rarely determine causal relationships. That’s why I’ve been following the evolving evidence about calcium supplements with interest. Calcium supplements are taken by almost 1 in 5 women, second only to multivitamins as the most popular supplement. When you look at all supplements that contain calcium, a remarkable 43% of the (U.S.) population consumes a supplement with calcium as an ingredient. As a single-ingredient supplement, calcium is almost always taken for bone health, based on continued public health messages that our dietary intake is likely insufficient, putting women (rarely men) at risk of osteoporosis and subsequent fractures. This messaging is backed by a number of studies that have concluded that calcium supplements can reduce bone loss and the risk of fractures. Calcium has an impressive health halo, and supplement marketers and pharmaceutical companies have responded. There are pills, liquids, and even tasty chewy caramel squares embedded with calcium. It’s also fortified in foods like orange juice. Supplements are often taken as “insurance” against perceived or real dietary shortfalls, and it’s easy and convenient to take a calcium supplement daily, often driven by the perception that more is better. Few may think that there is any risk to calcium supplements. But there are now multiple safety signals that these products do have risks. And that’s cause for concern. (more…)

Posted in: Herbs & Supplements, Nutrition

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Who takes dietary supplements, and why?

If you’re a regular reader of this blog, I’ll bet you’re not a regular consumer of vitamins or supplements. I’m in that group. Aside from sporadic vitamin D in winter, I don’t take any vitamins or supplements routinely, nor do I give any to my children. Your reasons may be close to mine: There is little to no evidence suggesting that dietary deficiencies are widespread, nor is there good evidence to suggest that vitamin supplements are beneficial in the absence of deficiency. I don’t have any need for an other supplements, nor am I confident in the scientific evidence for many of them.This position of “no supplements” is a cautious and conservative one, but is based on a consideration of the scientific evidence. I view decisions about healthcare as evaluations of risk and benefit, and then cost if necessary. Given supplementation (with some exceptions) has no demonstrable benefits and, in some cases, a little risk, the odds favour not supplementing in most cases. Add in costs, and it’s even less attractive as a routine health strategy.

Yet a decision not to take vitamins or supplements regularly is becoming a minority position. Supplement use has grown over the past 40 years among Americans, with the National Health and Nutrition Examination Survey (NHANES) showing steadily increasing utilization among younger and older adults:
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Posted in: Herbs & Supplements, Nutrition, Science and Medicine

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Death as a Foodborne Illness Curable by Veganism

Most reputable sources of nutrition information recommend a diet high in fruits and vegetables and low in red meat. Vegans go much further. Strict vegans reject all animal products including fish, eggs, and milk. Some vegans come across like religious zealots. Here are some comments recently posted by vegans on Facebook:

  • Right now the biggest social issue facing the world is the violence and suffering of animals.
  • The dairy industry is the number one feminist issue facing our modern society.
  • I expect within a generation that milk will be viewed as the most unhealthy habit after cigarettes. I bet it is responsible for more disease than anything else in the US. Dairy products promote all stages of cancer. [In fact, low fat dairy can be protective against some types of cancer]
  • Milk contains blood and puss[sic]
  • Humans are not omnivores; they are herbivores. [Most biologists would disagree.]

I was even told that that anyone who really cares about the welfare of others must promote veganism. It seems I am an evil, uncaring person if I waste my time writing about any other subject.

Vegans offer some good arguments based on ethics, environmental protection, cruelty to animals, and sustainability.  I won’t get into those issues here. I’ll only address the scientific evidence behind the health claims. How does this description of a video strike you?:

Death in America is largely a foodborne illness. Focusing on studies published just over the last year in peer-reviewed scientific medical journals, [Hardly any of the studies he cites were published over the last year.] Michael Greger, M.D., offers practical advice on how best to feed ourselves and our families to prevent, treat, and even reverse many of the top 15 killers in the United States.[emphasis added] (more…)

Posted in: Nutrition

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Should you be “Eating Clean”?

Like many of you I’m interested in the science of good nutrition. In general, I’ve come to be pretty skeptical of the nutritional literature, as so many studies seem to follow the same trajectory that we see with drug studies: Trivial changes in non-relevant outcomes, a failure to consider the results in the context of the accumulated scientific evidence and often, significant conflicts of interest. What’s worse, “real world” nutritional studies aren’t blinded and they’re rarely prospective. So we’re left to dig through observational studies and try to sort out correlation from causation. It’s little wonder that so many consumers are confused about the basics of healthy eating. Many believe that vitamins supplements are both beneficial and routinely necessary (they are not) and that the latest “superfood” is all that’s standing between themselves and immortality. But nutritional science is important, and I’m always pleased when patients initiate discussions about weight loss, or just improving their dietary habits. After all, obesity is a significant risk factor for an array of chronic illnesses. Improving our dietary patterns should pay off with improved health.. A regular challenge I face is that my patient that has already decided to use a highly restrictive weight loss plan in order to achieve a specific weight loss goal. I always caution them to take a long-term view. Weight loss is easy. Maintaining that loss is the challenge. Most “diets” fail. So I’m critical of useless interventions (like food intolerance blood tests) or faddy diets (like going gluten-free) with the hope of easy weight loss. At its core, weight loss and weight maintenance comes down to caloric balance. Permanent weight loss requires permanent dietary changes. And how we spend our “calories” matters.

Over the past few months I’ve seen a few friends and colleagues announce that they’ve decided to transform their diet, lose weight, and “eat clean”. When I asked what was “clean” food, no-one seems to have a consistent answer. The most common response was that “eating clean” meant cutting out processed foods. But to others, eating clean meant avoiding meat, anything with GMOs, wheat and sometimes milk. It seemed to mean something different to everyone. It reminds me a bit of Humpty Dumpty in Through the Looking Glass:

‘When I use a word,’ Humpty Dumpty said, in rather a scornful tone, ‘it means just what I choose it to mean — neither more nor less.’

Is “eating clean” just a faddish buzzword? There are a number of personalities competing in the “eating clean” dietary space. The pioneer seems to be Tosca Reno, who has the Eat-Clean Diet and about a dozen related books based on the same idea. But  she’s not alone, as there are several other books with related names, including Terry Walters with her “Clean Food” books. Success breeds competition, it seems. Given Reno’s book appears to be the most popular, I’ll take her plan as the template. She outlines the principles of how she defines eating clean in her 2007 book. I’ve added my comments after each principle. (more…)

Posted in: Nutrition

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The Shred Diet: A Minimally Kooky Way To Lose Weight

book-cover-shred

With New Years’ weight loss resolutions freshly made, let’s take a science-based look at another of the latest diet books being promoted by various public relations agencies. In my last post we explored the claims made by the hysterical Eat To Save Your Life authors in their book featuring a demonic cheeseburger on its cover jacket. Today I will review, Shred: The Revolutionary Diet ‚ 6 Weeks, 4 Inches, 2 Sizes, by Ian K. Smith, M.D.

I’m not sure what images the word “shred” conjures up for you, but if they have anything to do with muscle-bound, uber-lean bodybuilders on steroids you will be pleased to note that this book has nothing to do with them. In fact, what you’ll find in this book is a rather practical and healthy eating and exercise prescription with recipes and careful calorie counting. You’ll also find one fairly harmless chapter of liver detox pseudoscience, and an odd command to stare at yourself in the mirror at the beginning of week six.

Quietly stand in front of the mirror, and look deeply into your eyes as if you’re trying to see all the way into the depths of your soul… [p. 167]

The purpose of this visual exercise is never explained.

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Posted in: Nutrition, Science and Medicine

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The Dr. Oz Red Palm Oil (non-) Miracle

Red Palm Oil Dr. Oz

If there is an antithesis to the principles of science-based medicine, it’s probably the Dr. Oz show. In this daytime television parallel universe, anecdotes are evidence. There are no incremental advances in knowledge — only medical miracles. And every episode neatly offers up three or four takeaway health nuggets that, more often than not, seem to leave the audience more ill-informed about health and medicine than they were 30 minutes earlier.

After I completed my post on Dr. Oz’s prolonged embrace of the “miracle” that is green coffee bean extract, a number of readers brought me up to speed. Green coffee beans are yesterday’s miracle. The new weight loss miracle for 2013 is red palm oil. This constant drive for miracles must keep the producers in a perpetual panic. They need at least five miracles per week. Having now watched a few episodes, I’m reminded of the classic “That Mitchell and Webb Look” skit where two nutritionists pick a new superfood. It could be just a matter of time until we see white veal profiled as a superfood in a future Dr. Oz episode.

If there is a common characteristic of complementary and alternative medicine (CAM) proponents who believe themselves to be scientific (and I include Dr. Oz in this group), it is that they extrapolate from weak clinical evidence to grandiose claims by cherry picking the most supportive strands of evidence to give the impression of being evidence-based. They have the belief, and then they look for the supporting evidence to bolster the claim. In short, to paraphrase a quote attributed to Hahns Kuhn, they use scientific evidence like a drunkard uses a light post: for support, not for illumination. As I noted with green coffee bean extract, Dr. Oz extrapolated from ambiguous, preliminary data to recommendations to consume green coffee bean extract as a weight loss strategy. Frankly, the evidence isn’t there, so I didn’t have high expectations with the latest miracle. All I knew going in about palm oil is that it’s used in most industrial food production and the demand for it is linked to massive destruction of tropical rainforests. But who doesn’t want longevity? So I sat down and watched another episode.

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Posted in: Nutrition

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Everything we eat causes cancer…sort of

Read meat causes cancer. No, processed meat causes cancer. OK, it’s both read meat and processed meat. Wait, genetically modified grain causes cancer (well, not really). No, aspartame causes cancer. No, this food coloring or that one causes cancer.

Clearly, everything you eat causes cancer!

That means you can avoid cancer by avoiding processed meats, red meat, GMO-associated food (no, probably not), aspartame, food colorings, or anything “unnatural.” Or so it would seem from reading the popular literature and sometimes even the scientific literature. As I like to say to my medical students, life is a sexually transmitted fatal disease that gets us all eventually, but most of us would like to delay the inevitable as long as possible and remain as healthy as possible for as long as possible. One of the most obvious ways to do accomplish these twin aims is through diet. While the parameters of what constitutes a reasonably healthy diet have been known for decades, diet still ranks high on the risk of concerns regarding actions we take on a daily basis that can increase our risk of various diseases. Since cancer is disease (or, I should say, cancers are diseases) that many, if not most, people consider to be the scariest, naturally we worry about whether certain foods or food ingredients increase our risk of cancer.

Thus was born the field of nutritional epidemiology, a prolific field with thousands of publications annually. Seemingly, each and every one of these thousands of publications gets a news story associated with it, because the media love a good “food X causes cancer” or “food Y causes heart disease” story, particularly before the holidays. As a consequence, consumers are bombarded with what I like to call the latest health risk of the week, in which, in turn, various foods, food ingredients, or environmental “toxins” are blamed and exonerated for a panoply of health problems, ranging from the minor to the big three, cardiovascular disease, diabetes, and cancer. It’s no wonder that consumers are confused, reacting either with serial alarm at each new “revelatory” study or with a shrug of the shoulders as each new alarm joins other alarms to produce a tinnitus-like background drone. Unfortunately, this cacophony of alarm also provides lots of ammunition to quacks, cranks, and crackpots to tout their many and varied diets that, they promise, will cut your risk of diseases like cancer and heart disease to near zero—but only if adhered to with monk-like determination and self-denial. (Yes, I’m talking about you, Dean Ornish, among others.)

All of this is why I really wanted to write about an article I saw popping up in the queue of articles published online ahead of print about a month ago. Somehow, other topics intervened, as did my vacation and then the holidays, and somehow I missed it last week, even though a link to the study sits in my folder named “Blog fodder.” Fortunately, it just saw print this week in its final version, giving me an excuse to make up for my oversight. It’s a study by one of our heroes (despite his occasional misstep) here on the SBM blog, John Ioannidis. It comes in the form of a study by Jonathan D. Schoenfeld and John Ioannidis in the American Journal of Clinical Nutrition entitled, brilliantly, Is everything we eat associated with cancer? A systematic cookbook review.
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Posted in: Cancer, Nutrition

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Nutrigenomics – Not Ready for Prime Time

Quackery in medicine takes many forms – use of bad science (pseudoscience), fraud, and reliance on mysticism are a few examples. Perhaps the most insidious form of dubious practice, however, is to use genuine and promising medical science to promote treatments that are simply not at the point of clinical application. New treatments, and especially new approaches to treatment, in medicine often take years or decades of research before we get to the point that we have sufficient clinical evidence of safety and effectiveness to apply the treatment in clinical practice.

One example of the premature promotion of an otherwise legitimate scientific medical treatment are the many dubious stem cell clinics promising cures for serious diseases. Stem cell science is real, but we are still in the long period of build up when we are mostly doing basic and animal research. Human clinical trials are just beginning.

Another treatment approach that is being prematurely promoted by some is nutrigenomics. The claim is that by analyzing one’s genes a personalized regimen of specific nutrients can be developed to help their genes function at optimal efficiency. One website that promises, “Genetics Based Integrative Medicine” contains this statement:

Nutrigenomics seeks to unravel these medical mysteries by providing personalized genetics-based treatment. Even so, it will take decades to confirm what we already understand; that replacing specific nutrients and/or chemicals in existing pathways allows more efficient gene expression, particularly with genetic vulnerabilities and mutations.

The money-quote is the phrase, “it will take decades to confirm what we already understand.” This is the essence of pseudoscience – using science to confirm what one already “knows.” This has it backwards, of course. Science is not used to “confirm” but to determine if a hypothesis is true or not.

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Posted in: Diagnostic tests & procedures, Nutrition

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Eat To Save Your Life: Another Half-True Diet Book

I am hesitant to review diet books because they are so often a tangled mess of fact and fiction. Teasing out their truth from falsehood is about as exhausting as delousing a long-haired elementary school student. However, after being approached by the authors’ PR agency with the promise of a book that contains science-based nutrition information I decided to agree to the review. This is how the book was described to me in an email:

In their provocative new book, Eat to Save Your Life, best-selling authors Dr. Jerre Paquette and Gloria Askew, RRN, sort through the piles of information and misinformation about nutrition to reveal the true connection between food and health. Fed up with the advertising hype and conflicting nutritional advice, the duo provides common sense explanations for consumers everywhere who are looking to make smart nutritional choices.

Unfortunately, I was sold (quite predictably) a bill of goods. And rather than ignore the book and simply not do a review, I figured that maybe a negative review would reduce the number of incoming PR requests for future tomes of pseudoscience. In the end, I’ll probably just become the focus of personal attacks by dedicated proponents of various snake oils. 

That being said, I thought it might be somewhat instructive to remind SBM readers of certain basic “warning signs of pseudoscience” that I accidentally overlooked in agreeing to review the book. For a more complete review of similar “signs” I highly recommend Dr. David Gorski’s 2007 classic, humorous take on predictable arguments and behaviors of alternative medicine proponents (written in the style of comedian Jeff Foxworthy).  As for me, I tend to think of much of the world of integrative medicine as a militant group of bakers eager to add odd, inert and occasionally toxic substances to cake recipes. 
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Posted in: Book & movie reviews, Nutrition

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The Obesity Paradox

Being fat is bad except when it’s good. It’s called “the obesity paradox.” (No, that isn’t a mis-spelling for “two physicians who treat fat people.”) The adverse health effects of obesity are well established, but there are exceptions. Obesity appears to confer an advantage in certain subgroups with conditions like heart disease and diabetes.

In the News

Casual consumers of some recent media reports might interpret them as an excuse to stop trying to lose excess weight, especially if they are diabetic. Others might think we have been lied to about the dangers of the obesity epidemic. The reality is more complicated. (more…)

Posted in: Nutrition

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