Can You Believe Clinical Studies

Written by Dr. Steve Chaney on . Posted in Believe Clinical Studies

The “Secret” About Clinical Studies Nobody Is Telling You

Author: Dr. Stephen Chaney

 

can you believe clinical studiesIt is so confusing. You get lots of advice in today’s world.

  • Your friend shares a new diet they read about and tells you how well it worked for her.
  • Your trainer puts you on a diet his sports guru recommended.
  • You read Dr. Strangelove’s health blog and decide you need to throw out all the foods in your refrigerator.
  • Your doctor tells you what you should eat and whether you should take supplements.
  • You decide to follow the recommendations of the American Heart Association or American Diabetes Association because they are the experts.

The problem is you are told all this advice is based on clinical studies – AND – most of the advice is conflicting. You don’t know who to believe, and, even worse, you are starting to wonder whether you can believe clinical studies.

I have covered the source of much of this confusion in my two books “Slaying The Food Myths”  and “Slaying The Supplement Myths.”  The Cliff Notes summary from these books is:

  • The placebo effect approaches 50% for things like feeling good, energy and mood.
  • Reputable scientists ignore testimonials and look for clinical proof.
  • What works for your friend or trainer may not work for you.
  • Any extreme diet that eliminates foods and food groups from your diet will cause short-term weight loss and improvements in health parameters like cholesterol, blood sugar, and blood pressure.
  • Reputable scientists look for studies documenting the long-term health outcomes of those diets. Some diets that look healthy short-term are unhealthy long-term.
  • Advocates of these fad diets emphasize short-term successes of their favorite diet and don’t even look for studies on long-term health outcomes.

Every clinical study has its flaws.

  • can you believe clinical studies doctorReputable scientists recognize this and don’t base their recommendations on individual studies. Instead, they base their recommendation on the preponderance of evidence from multiple studies.
  • Strangelove and other bloggers don’t understand that. They select studies that support their viewpoint and ignore the rest.
  • Some clinical studies are better than others. In fact, some really bad clinical studies get published.
  • Reputable scientists know how to distinguish between good studies and bad studies. They ignore bad studies and base their recommendations on good studies.
  • Strangelove, other bloggers, and the news media aren’t scientists. They don’t know how to distinguish between good and bad studies. They simply report the studies that support their viewpoint.
  • Strangelove, other bloggers, and the new media prefer audience over accuracy. They measure success by the number of readers rather than the accuracy of their articles.
  • “Man bites dog” stories gather the most readers. Dr. Strangelove and the media focus on studies that challenge the advice you have been getting from the health and nutrition establishment. The studies may not be accurate, but they attract a lot of readers.
  • Responsible scientists will give you the boring truth, even if it doesn’t attract many readers.

In my books I help you navigate through the world of conflicting clinical studies, so you can base your decisions on the very best clinical studies. However, there is one more “secret” you need to know. It is one that every scientist knows, but the public almost never hears about.

However, before I tell you the secret, let me set up this discussion by talking about glycemic index and use one food, the lowly banana, as an example.

 

Glycemic Index – How Sweet It Is

can you believe clinical studies glycemic indexIf you are a diabetic or are following one of the many low-carb diets, you probably know all about glycemic index. You probably have a glycemic index list in your kitchen or on your phone. You probably consult that list often to determine which foods you can eat and which you can’t. (If you aren’t familiar with the term, it is simply a measure of how big a blood sugar increase each food causes).

What if I were to tell you the glycemic index list you are relying on may not apply to you?

Then there is the lowly banana. You have probably heard from your trainer or favorite nutrition blog that you should avoid bananas because they are too high in sugar. However, if you were to consult a nutrition expert, they would tell you that bananas are a great choice. Bananas are nutrient powerhouses. In addition, a ripe banana has a glycemic index of 51 and anything under 55 is considered low-glycemic.

What if I were to tell you that the advice about bananas that both your trainer and nutrition experts give you is correct for some people? You just need to find out which advice applies to you.

 

The Secret About Clinical Studies Nobody Is Telling You

 

can you believe clinical studies secretNow, you are ready to learn the secret. It is this: Clinical studies are based on averages, and none of us are average. Because of that, even the very best clinical study results may not apply to you.

In a way, this reminds me of “The Wizard Of Oz.” You remember the story. If you were sitting in front of the curtain, the wizard was impressive. He was all powerful. He was making learned pronouncements about the way things should be. But, behind the curtain, the reality was quite different.

The authors of most clinical studies and most nutrition gurus make learned pronouncements about the life changes you should make based on the results of their study. They seldom let you peak behind the curtain to see how much the results vary from one individual to the next.

One exception is a recent study that reported individual variation in blood sugar responses to various foods. There are lots of examples from that study I could share with you, but I will use bananas versus sugar cookies as an example.

When they reported average values, bananas had a glycemic index of 51 and sugar cookies had a glycemic index of around 59. Both of those values are very close to what you find in most glycemic index lists.

The glycemic index of a banana is only 13% less than the glycemic index of sugar cookies. However, since the cut-off between high and low glycemic indices is 55, bananas are classified as low-glycemic and sugar cookies are classified as high-glycemic. According to conventional wisdom, bananas are good for you and sugar cookies are bad for you. But, what about individual variation? Does that wisdom really apply to you?

can you believe clinical studies blood sugarBased on the range of blood-sugar responses reported in the paper, I have created the scatter plot on the left to help you visualize the range of individual responses. The horizontal line represents the average glycemic index for sugar cookies and bananas. The dots represent the glycemic response of individuals in the study. For some people in the study the glycemic response to bananas was greater than the average glycemic response to sugar cookies. For other individuals the glycemic response to sugar cookies was less than the average glycemic response to bananas.

You can see the extent of individual variability even more clearly in the figure on the right, which was reproduced from one of the figures in the paper. The authors reported that for some individuals, bananas caused no increase in blood sugar while sugar cookies caused a big spike in blood sugar (the response most people would expect). However, for other individuals, sugar cookies caused no increase in blood sugar while bananas caused a big spike in blood sugar.

can you believe clinical studies glycemic loadNow you understand why I told you the glycemic list you are relying on may not apply to you. You also understand why I said the advice you have been given about bananas might not apply to you.

Lest you think this just applies to bananas, the same study reported that individual blood sugar responses varied by:

  • 4-fold for sugar-sweetened soft drinks, grapes, and apples.
  • 5-fold for rice.
  • 6-fold for bread and potatoes.
  • 7-fold for ice cream and dates.

 

Can You Believe Clinical Studies?

 

can you believe clinical studies provenI used glycemic index as an example. The same principle is true for almost any clinical study.

Let’s consider clinical studies looking at the effect of diet on health outcomes such as heart disease.

  • The headlines may say that a particular diet significantly decreases your risk of heart disease.
  • When you read the paper behind the headlines, you discover that the diet decreases heart disease by 15%. That result may be statistically significant, but it is hardly life changing.
  • If you could peak behind the curtain you might discover that the diet cut heart disease risk in half for some individuals and had no effect on heart disease risk for others.

Clinical studies looking at weight loss are another example.

  • You might be told “Clinical studies show people who follow diet X lose 12 pounds in 6 weeks”.
  • That’s an average value. If you could peak behind the curtain, you would discover that nobody lost exactly 12 pounds. Some lost more. Some lost less. Some may have actually gained weight.

I am not saying that well-designed clinical studies are useless. They are a good foundation for general nutrition guidelines. What I am saying is that not every nutritional guideline applies to you.

What Does This Study Mean For You?

Some of you may be saying: “What does this mean for me?” When you carry the concept of individual variability through to its ultimate conclusion, the bottom line message is:

  • Conclusions from clinical trial results are based on averages – none of us are average.
  • Daily Values (DV) are based on averages – none of us are average.
  • Nutritional recommendations for optimal health are based on averages – none of us are average.
  • The identified risk factors for developing diseases are based on averages – none of us are average.
  • Glycemic index lists are based on averages. None of us are average.

That means lots of the advice you may be getting about your risk of developing disease X, the best diet to prevent disease X, the best foods to keep your blood sugar under control, or the role of supplementation in preventing disease X may be generally true – but it might not be true for you.

So, my advice is not to blindly accept the advice of others about what is right for your body. Just because some health guru recommends it, doesn’t mean it is right for you. Just because it worked for your buddy, doesn’t mean it will work for you. Learn to listen to your body. Learn what foods work best for you. Learn what exercises just feel right for you. Learn what supplementation does for you.

Don’t ignore your doctor’s recommendations, but don’t be afraid to take on some of the responsibility for your own health. You are a unique individual, and nobody else knows what it is like to be you.

 

Final Thought: Glycemic Index Versus Glycemic Load

Since I used glycemic index as an example in this discussion, I feel obligated to discuss the difference between glycemic index and glycemic load. Glycemic index is based on the blood sugar response to 50 gm of carbohydrate in various foods. Glycemic load is based on the blood sugar response to a serving of that food. In some cases, that’s a big difference.

Glycemic index can sometimes be deceiving. Let me give you two examples. Carrots and watermelon are often found on lists of high glycemic foods. If that sounds a bit weird to you, it is.

One serving (one medium carrot) of carrots has 6 grams of carbohydrate (of which, only 2.9 grams is sugar). To get 50 grams of carbohydrate, you would need to eat 8 carrots. Watermelon is, not surprisingly, mostly water. One serving (a 1-inch thick sliced wedge or one cup) of watermelon contains 11 grams of carbohydrate (of which, 9 grams of sugar). To get 50 grams of sugar, you would need to eat 4.5 cups of watermelon. For both carrots and watermelon, their glycemic load is a more accurate measure of their effect on your blood sugar than is their glycemic index.

Leaving individual variation out of consideration, here is a simple guide for choosing low-glycemic foods if you are trying to control your blood sugar levels.

  • Foods with a low glycemic index are generally a good choice.
  • Many foods with a high glycemic index also have a high glycemic load.
  • If you are uncertain about some foods on the high glycemic index list, also check their glycemic load.

 

The Bottom Line

Clinical studies are the bedrock on which we build recommendations for diet, exercise, and supplementation. In the article above I discuss how to distinguish between good and bad clinical studies. I also discuss how individual variability influences the interpretation of clinical studies.

 

For more details read the article above.

 

These statements have not been evaluated by the Food and Drug Administration. This information is not intended to diagnose, treat, cure or prevent any disease.

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Latest Article

What Is The Planetary Diet?

Posted May 21, 2019 by Dr. Steve Chaney

Is Your Diet Destroying The Planet?

Author: Dr. Stephen Chaney

 

Earth Day has come and gone, but you are still committed to saving the planet. You save energy. You recycle. You drive an electric car. But is your diet destroying the planet?

This is not a new question, but a recent commission of international scientists has conducted a comprehensive study into our diet and its effect on our health and our environment. Their report (W. Willet et al, The Lancet, 393, issue 10170, 447-492, 2019 ) serves as a dire warning of what will happen if we don’t change our ways. I touched on this report briefly in a previous issue of “Health Tips From The Professor,” What Is The Flexitarian Diet , but this topic is important enough that it deserves an issue all its own.

The commission carefully evaluated diet and food production methods and asked three questions:

  • Are they good for us?
  • Are they good for the planet?
  • Are they sustainable? Will they be able to meet the needs of the projected population of 10 billion people in 2050 without degrading our environment.

The commission described the typical American diet as a “lose-lose diet.” It is bad for our health. It is bad for the planet. And it is not sustainable.

In its place they carefully designed their version of a primarily plant-based diet they called a “win-win diet.”  It is good for our health. It is good for the planet. And, it is sustainable.

In their publication they refer to their diet as the “universal healthy reference diet” (What else would you expect from a committee?). However, it has become popularly known as the “Planetary Diet.”

I have spoken before about the importance of a primarily plant-based diet for our health. In that context it is a personal choice. It is optional.

However, this report is a wake-up call. It puts a primarily plant-based diet in an entirely different context. It is essential for the survival of our planet. It is no longer optional.

If you care about global warming…If you care about saving our planet, there is no other choice.

How Was The Study Done?

The study (W. Willet et al, The Lancet, 393, issue 10170, 447-492, 2019 ) was the report of the EAT-Lancet Commission on Healthy Diets from Sustainable Food Systems. This Commission convened 30 of the top experts from across the globe to prepare a science-based evaluation of the effect of diet on both health and sustainable food production through the year 2050. The Commission included world class experts on healthy diets, agricultural methods, climate change, and earth sciences. The Commission reviewed 356 published studies in preparing their report.

 

Is Your Diet Destroying The Planet?

When they looked at the effect of food production on the environment, the Commission concluded:

  • “Strong evidence indicates that food production is among the largest drivers of global environmental change.” Specifically, the commission reported:
  • Agriculture occupies 40% of global land (58% of that is for pasture use).
  • Food production is responsible for 30% of global greenhouse gas emissions and 70% of freshwater use.
  • Conversion of natural ecosystems to croplands and pastures is the largest factor causing species to be threatened with extinction. Specifically, 80% of extinction threats to mammals and bird species are due to agricultural practices.
  • Overuse and misuse of nitrogen and phosphorous in fertilizers causes eutrophication. In case you are wondering, eutrophication is defined as the process by which a body of water becomes enriched in dissolved nutrients (such as phosphates from commercial fertilizer) that stimulate the growth of algae and other aquatic plant life, usually resulting in the depletion of dissolved oxygen. This creates dead zones in lakes and coastal regions where fish and other marine organisms cannot survive.
  • About 60% of world fish stocks are fully fished and more than 30% are overfished. Because of this, catch by global marine fisheries has been declining since 1996.
  • “Reaching the Paris Agreement of limiting global warming…is not possible by only decarbonizing the global energy systems. Transformation to healthy diets from sustainable food systems is essential to achieving the Paris Agreement.”
  • The world’s population is expected to increase to 10 billion by 2050. The current system of food production is unsustainable.

When they looked at the effect of the foods we eat on the environment, the Commission concluded:

  • Beef and lamb are the biggest contributors to greenhouse gas emissions and land use.
  • The concern about land use is obvious because of the large amount of pasture land required to raise cattle and sheep.
  • The concern about greenhouse gas emissions is because cattle and sheep are ruminants. They not only breathe out CO2, but they also release methane into the atmosphere from fermentation in their rumens of the food they eat. Methane is a potent greenhouse gas, and it persists in the atmosphere 25 times longer than CO2. The single most important thing we can do as individuals to reduce greenhouse gas emissions is to eat less beef and lamb. [Note: grass fed cattle produce more greenhouse gas emissions than cattle raised on corn because they require 3 years to bring to market rather than 2 years.]
  • In terms of energy use beef, lamb, pork, chicken, dairy and eggs all require much more energy to produce than any of the plant foods.
  • In terms of eutrophication, beef, lamb, and pork, all cause much more eutrophication than any plant food. Dairy and eggs cause more eutrophication than any plant food except fruits.
  • In contrast, plant crops reduce greenhouse gas emissions by removing CO2 from the atmosphere.

 

What Is The Planetary Diet?

In the words of the Commission: “[The Planetary Diet] largely consists of vegetables, fruits, whole grains, legumes, nuts, and unsaturated oils. It includes a low to moderate amount of seafood, poultry, and eggs. It includes no or a very low amount of red meat, processed meat, sugar, refined grains, and starchy vegetables.”

When described in that fashion it sounds very much like other healthy diets such as semi-vegetarian, Mediterranean, DASH, and Flexitarian. However, what truly distinguishes it from the other diets is the restrictions placed on the non-plant portion of the diet to make it both environmentally friendly and sustainable. Here is a more detailed description of the diet:

  • It starts with a vegetarian diet. Vegetables, fruits, beans, nuts, soy foods, and whole grains are the foundation of the diet.
  • It allows the option of adding one serving of dairy a day (It turns out that cows produce much less greenhouse emissions per serving of dairy than per serving of beef. That’s because cows take several years to mature before they can be converted to meat, and they are emitting greenhouse gases the entire time).
  • It allows the option of adding one 3 oz serving of fish or poultry or one egg per day.
  • It allows the option of swapping seafood, poultry, or egg for a 3 oz serving of red meat no more than once a week. If you want a 12 oz steak, that would be no more than once a month.

This is obviously very different from the way most Americans currently eat. According to the Commission:

  • “This would require greater than 50% reduction in consumption of unhealthy foods, such as red meat and sugar, and greater than 100% increase in the consumption of healthy foods, such as nuts, fruits, vegetables, and legumes.”
  • “In addition to the benefits for the environment, “dietary changes from current diets to healthy diets are likely to substantially benefit human health, averting about 10.8-11.6 million deaths per year globally.”

What Else Did The Commission Recommend?

In addition to changes in our diets, the Commission also recommended several changes in the way food is produced. Here are a few of them.

  • Reduce greenhouse gas emissions from the fuel used to transport food to market.
  • Reduce food losses and waste by at least 50%.
  • Make radical improvements in the efficiency of fertilizer and water use. In terms of fertilizer, the change would be two-fold:
    • In developed countries, reduce fertilizer use and put in place systems to capture runoff and recycle the phosphorous.
    • In third world countries, make fertilizer more available so that crop yields can be increased, something the Commission refer to as eliminating the “yield gap” between third world and developed countries.
  • Stop the expansion of new agricultural land use into natural ecosystems and put in place policies aimed at restoring and re-foresting degraded land.
  • Manage the world’s oceans effectively to ensure that fish stocks are used responsibly and global aquaculture (fish farm) production is expanded sustainability.

What we can do: While most of these are government level policies, we can contribute to the first three by reducing personal food waste and purchasing organic produce locally whenever possible.

What Does This Mean For You?

If you are a vegan, you are probably asking why the Commission did not recommend a completely plant-based diet. The answer is that a vegan diet is perfect for the health of our planet. However, the Commission wanted to make a diet that was as consumer-friendly as possible and still meet their goals of a healthy, environmentally friendly, and sustainable diet.

If you are eating a typical American diet or one of the fad diets that encourage meat consumption, you are probably wondering how you can ever make such drastic changes to your diet. The answer is “one step at a time.”  If you have read my books “Slaying The Food Myths” or “Slaying the Supplement Myths,”  you know that my wife and I did not change our diet overnight. Our diet evolved to something very close to the Planetary Diet over a period of years.

The Commission also purposely designed the Planetary Diet so that you “never have to say never” to your favorite foods. Three ounces of red meat a week does not sound like much, but it allows you a juicy steak once a month.

Sometimes you just need to develop a new mindset. As I shared in my books, my father prided himself on grilling the perfect steak. I love steaks, but I decided to set a few parameters. I don’t waste my red meat calories on anything besides filet mignon at a fine restaurant. It must be a special occasion, and someone else must be buying. That limits it to 2-3 times a year. I still get to enjoy good steak, and I stay well within the parameters of the Planetary diet.

Develop your strategy for enjoying some of your favorite foods within the parameters of the Planetary Diet and have fun with it.

The Bottom Line

 

Is your diet destroying the planet? This is not a new question, but a recent commission of international scientists has conducted a comprehensive study into our diet and its effect on our health and our environment. Their report serves as a dire warning of what will happen to us and our planet if we don’t change our ways.

The Commission carefully evaluated diet and food production methods and asked three questions:

  • Are they good for us?
  • Are they good for the planet?
  • Are they sustainable? Will they be able to meet the needs of the projected population of 10 billion people in 2050 without degrading our environment.

The Commission described the typical American diet as a “lose-lose diet.”  It is bad for our health. It is bad for the planet. And it is not sustainable.

In its place they carefully designed their version of a primarily plant-based diet they called a “win-win diet.”  It is good for our health. It is good for the planet. And, it is sustainable.

In their publication they refer to their diet as the “universal healthy reference diet” (What else would you expect from a committee?). However, it has become popularly known as the “Planetary Diet.”

The Planetary Diet is similar to other healthy diets such as semi-vegetarian, Mediterranean, DASH, and Flexitarian. However, what truly distinguishes it from the other diets is the restrictions placed on the non-plant portion of the diet to make it both environmentally friendly and sustainable (for details, read the article above).

I have spoken before about the importance of a primarily plant-based diet for our health. In that context it is a personal choice. It is optional.

However, this report is a wake-up call. It puts a primarily plant-based diet in an entirely different context. It is essential for the survival of our planet. It is no longer optional.

If you care about global warming…If you care about saving our planet, there is no other choice.

For more details read the article above.

 

These statements have not been evaluated by the Food and Drug Administration. This information is not intended to diagnose, treat, cure or prevent any disease.

 

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