Search results: research bias

Aubrey Gordon.  What We Don’t Talk About When We Talk About Fat.  Beacon Press. 2020.

I didn’t think I’d want to read or write about this book but I couldn’t put it down and ended up doing a blurb for it:

In What We Talk About, Audrey Gordon gives us an authoritative, forceful, splendidly written, and deeply moving account of the shockingly personal hostility she and other fat people must endure on a daily basis.  You don’t have to agree with her interpretation of the research on fatness and its consequences to sign on to her thoroughly convincing demand for respect as a human being and for what she calls “fat justice.”  This book changed my thinking, and in the best possible way.

Here are two short excerpts:

While these [other fat activist] approaches work for many, I describe mine as work for fat justice.  Body positivity has shown me that our work for liberations must explicitly name fatness as its battlground—because when we don’t, each of us are likely to fall back on our deep-seated, faulty cultural beliefs about fatness and fat people, claiming to stand for “all bodies” while we implicitly and explicitly exclude the fattest among us.  I yearn for more than neutrality, acceptance, and tolerance—all of which strike me as a meek plea to simply stop harming us, rather than asking for help in healing that harm or requesting that each of us unearth and examine our existing biases against fat people (p. 6)

But the first step for all of us will be to let go of the magical thinking of thinness.  Stop believing that a thinner body will bring us better relationships, dream jobs, obedient children, beautiful homes.  Stop waiting to do the things we love until we’ve lost ten, twenty, fifty, one hundred pounds.  Come to truly believe what we already know, and what so much data tells us: the vast majority of us don’t lose significant amounts of weight and the few who do don’t maintain weight loss in the long term.  Nearly twenty years of dieting has shown me that I will never be thin….I also believe that my life is worth living, worth embracing, worth loving, and celebrating.  And it’s worth all of that now—not two hundred pounds from now (p. 161).

The potato industry has a problem.  Some nutrition experts do not recommend them and argue that potatoes—especially French fries—raise blood sugar levels and should be excluded from recommendations to increase vegetable intake (I love potatoes in any form but try not to overeat them—everything in moderation if you can manage that, and I can).

In any case, the The Alliance for Potato Research & Education (APRE) is devoted to protecting the reputation—and sales–of potatoes, and funds research for that purpose.

The study: Daily intake of non-fried potato does not affect markers of glycaemia and is associated with better diet quality compared with refined grains: a randomised,crossover study in healthy adults.   EA Johnston et al.  British Journal of Nutrition (2020), 123, 1032–1042.

Results: “Compared with refined grains, the HEI-2015 Healthy Eating Index] scores..were higher following the potato condition. Consuming non-fried potatoes resulted in higher diet quality, K  [potassium] and fibre intake, without adversely affecting cardiometabolic risk.”

Financial Support: The Alliance for Potato Research and Education provided funds for the research conducted. Their staff were not involved in any aspects of conducting the study, analyzing the data or interpreting the results presented.

Comment: The APRE says it remains firmly committed to the scientific integrity of industry-funded research”  Its guidelines for research integrity sound good, but don’t address the inherent problems of industry-funded research: the well established “funding effect” that virtually guarantees that industry-funded research will produce results that favor the sponsor’s interests, and the also well established observation that investigator bias tends to occur at an unconscious level.  The exclusion of fried potatoes from this particular study suggests that the investigators know that frequent eating of French fries is a marker of poor diet quality.  I think potatoes have a place in healthy diets and that much depends on their particular role and preparation.  As with much in nutrition, the potato situation is complicated, and industry funding does not help with clarification.

Stevia Beverage Consumption prior to Lunch Reduces Appetite and Total Energy Intake without Affecting Glycemia or Attentional Bias to Food Cues: A Double-Blind Randomized Controlled Trial in Healthy Adults.  Nikoleta S Stamataki, Nikoleta S Stamataki, Corey Scott, Rebecca Elliott, Shane McKie, Douwina Bosscher, John T McLaughlin. The Journal of Nutrition, Volume 150, Issue 5, May 2020, Pages 1126–1134.

Method: This randomized, controlled, double-blind crossover study gave 20 healthy participants water or beverages with various sweeteners before lunch.  The investigators measured how much participants ate after consuming each drink.

Conclusion:  “This study found a beneficial and specific effect of a stevia beverage consumed prior to a meal on appetite and energy intake in healthy adults.”

Conflict of interest statement: “This study was supported by funding from the UK’s Biotechnology and Biological Sciences Research Council (BBSRC) through a BBSRC Case Studentship awarded to NSS. Cargill prepared and provided the test products free of charge.  Author disclosures: DB and CS were employed by Cargill during the preparation of this manuscript, and Cargill produces stevia. The other authors report no conflicts of interest.”

Comment:  The artificial sweetener Stevia is manufactured by Cargill.  Two of the authors work for Cargill.  Cargill has a vested interest in demonstrating that consumption of Stevia helps people lose weight.  Whether artificial sweeteners help with weight loss is a question much debated.  Industry-funded studies like his one tend to find benefits.  Some independently funded studies do too but others do not.

My guess: artificial sweeteners might help some people, but their overall benefits, if any, are small.

My take: one of my food rules is not to eat anything artificial, so Stevia is off my dietary radar from the get-go.

Arleen Tuchman.  Diabetes: A History of Race and Disease.  Yale University Press, 2020.I did a blurb for this book:

This is a superb, deeply researched history of the role of racism and class bias in perceptions of type 2 diabetes.  Its root causes?  Poverty and discrimination—a new vision for a prevention agenda.

Tuchman does for type 2 diabetes what historians of other diseases have done: explore the central role of race and racism.  Racism, she explains, can

Generate ill health by producing pathological responses to the stress of living in a society in which skin color is endowed with privileges denied to others.  Racism, in other words, can make people sick.  In this way, racism—not race—becomes a fundamental cause of differential disease rates, making it impossible to draw a sharp line between what is biological and what is social.

As she documents, health professionals first viewed diabetes as a disease of the Jews—perhaps because they went to doctors more often.   It took decades for scientists to distinguish type 1 from type 2 diabetes, and more decades to recognize that its higher prevalence among non-white minority groups might be due to the obesity-promoting diets and lifestyles of poverty.

For documentation of the social determinants of health, this book is an instant classic.

The report of the 2020 Dietary Guidelines Advisory Committee is now available in online preprint.

It sets a record at 835 pages.

Its conclusions are highly consistent with those of previous Dietary Guidelines.

It recommends eating more of these foods:

Common characteristics of dietary patterns associated with positive health outcomes include higher intake of vegetables, fruits, legumes, whole grains, low- or nonfat dairy, lean meat and poultry, seafood, nuts, and unsaturated vegetable oils.

It recommends eating less of these foods:

The Committee found that negative (detrimental) health outcomes were associated with dietary patterns characterized by higher intake of red and processed meats, sugar-sweetened foods and beverages, and refined grains.

It retained the recommendation: Eat less red and processed meats

It retained the recommendation to eat less saturated fat (replace with polyunsaturated or monounsaturated)

Thus, the Committee recommends that dietary cholesterol and saturated fat intake be as low as possible within a healthy dietary pattern, and that saturated fat intake be limited to less than of 10 percent of total energy intake, as recommended by the 2015-2020 Dietary Guidelines for Americans. This recommendation applies to adults and children ages 2 years and older.

It tightened up restrictions on alcoholic beverages from 2 drinks a day for men to 1 drink:

The Committee concluded that no evidence exists to relax current Dietary Guidelines for Americans recommendations, and there is evidence to tighten them for men such that recommended limits for both men and women who drink would be 1 drink per day on days when alcohol is consumed.

It tightened up restrictions on added sugars, from 10% of calories to 6%:

After considering the scientific evidence for the potential health impacts of added sugars intake, along with findings from model-based estimations of energy available in the dietary pattern after meeting nutrient requirements, the Committee suggests that less than 6 percent of energy from added sugars is more consistent with a dietary pattern that is nutritionally adequate while avoiding excess energy intake from added sugars than is a pattern with less than 10 percent energy from added sugars.

What’s missing?

• Salt: The report says remarkably little about sodium beyond that it is overconsumed and people should “reduce sodium intake.”  It’s possible that I missed it, but I could not find suggestions for quantitative limits.
• Ultraprocessed: The word does not appear in the report except in the references.  A large body of evidence supports an association of ultraprocessed foods to poor health.  If the committee considered this evidence, it did not spell it out explicitly.
• Sustainability: This was off the table from the beginning but this committee recommends that it be considered next time in the context of a food systems approach to the Dietary Guidelines (p.771).

Comment

This is an impressive, solid, conservative review of the existing science highly consistent with previous Dietary Guidelines but with mostly stronger recommendations.

This committee was up against:

• A tight time frame
• A first-time mandate to review literature on infancy, pregnancy, and lactation in addition to that for adults
• A first-time process in which the agencies set the research agenda, not the committee
• The Coronavirus pandemic

At the outset, I was concerned that the committee members might be heavily biased in favor of food industry interests.  If they were, such biases do not show up in the final report.  I think this committee deserves much praise for producing a report of this quality under these circumstances.

Want to weigh in on it? 

The agencies are taking public comments until August 13.  On August 11, there will be an online public meeting for even more comments.

What’s next?

This report is advisory, only.  USDA and HHS must boil this down to the actual 2020 Dietary Guidelines.  Whereas the committee process was transparent, the boiling down process is highly secretive, or was in 2015.  It will be interesting to see what the agencies do, especially given the heavy lobbying by proponents of meat, saturated fat, and low-carbohydrate diets.

I swear I’m not making this up.

The study: Effect of Nut Consumption on Erectile and Sexual Function in Healthy Males: A Secondary Outcome:  Analysis of the FERTINUTS Randomized Controlled Trial.  Albert Salas-Huetos, Jananee Muralidharan, Serena Galiè, Jordi Salas-Salvadó, and Mònica Bulló.  Nutrients 2019, 11(6), 1372; https://doi.org/10.3390/nu11061372.

The conclusion: “Including nuts in a regular diet significantly improved auto-reported orgasmic function and sexual desire.”

The funder: “This work was partially supported by the International Nut and Dried Fruit Council (INC)…INC is a non-profit entity registered at the Register of Foundations of Catalonia, Spain. Nuts were supplied by Crisolar, Spain.

Comment: I love these results, and have no doubt that the funder did too.  I can only imagine the ads based on this study.  News accounts too (here’s a good one from London’sDaily Mail).

The results were so interesting that a separate group reviewed the data and confirmed that the numbers led to the same results.  This is not surprising.  Most studies of bias in research show that it turns up mainly in the way the research question is framed or in the interpretation of the data, not in the conduct of the science or collection of data.

Hey guys: have problems?  Eat a mixture of raw walnuts, almonds, and hazelnuts and collect your own data!

A headline in FoodNavigator.com got my attention: “Heart-healthy walnuts could be the next big meat alternative as campaigns build on plant-based trend.”

Hoping to exponentially increase consumers’ already growing interest in walnuts, the California Walnut Board today is launching a two-prong marketing effort that will promote the nut’s health benefits and versatility.

The prongs are in-store promotions and a global marketing campaign—in nine countries no less—emphasizing how you only need to eat three handfuls a week to get their health benefits.

The article notes that the health benefits are based on published research.  Alas, it fails to mention that the cited study was ” funded by The California Walnut Commission.”

The study:  Walnuts and Vegetable Oils Containing Oleic Acid Differentially Affect the Gut Microbiota and Associations with Cardiovascular Risk Factors: Follow-up of a Randomized, Controlled, Feeding Trial in Adults at Risk for Cardiovascular Disease.  Alyssa M Tindall, Christopher J McLimans, Kristina S Petersen, Penny M Kris-Etherton, Regina Lamendella.  The Journal of Nutrition, nxz289, https://doi.org/10.1093/jn/nxz289.  

Its conclusion: “…gut microbiota may contribute to the health benefits of walnut consumption in adults at cardiovascular risk.”

The California Walnut Commission has been diligent in funding studies reporting benefits from walnut consumption.  Here’s another one:

The study: Effect of a 2-year diet intervention with walnuts on cognitive decline.  The Walnuts And Healthy Aging (WAHA) study: a randomized controlled trial.  Aleix Sala-Vila, Cinta Valls-Pedret, Sujatha Rajaram, Nina Coll-Padrós, Montserrat Cofán, Mercè Serra-Mir, Ana M Pérez-Heras, Irene Roth, Tania M Freitas-Simoes, Mónica Doménech, Carlos Calvo,1,2 Anna López-Illamola, Edward Bitok, Natalie K Buxton, Lynnley Huey, Adam Arechiga, Keiji Oda, Grace J Lee, Dolores Corella, Lídia Vaqué-Alcázar, Roser Sala-Llonch, David Bartrés-Faz, Joan Sabaté, and Emilio Ros.  Am J Clin Nutr 2020;00:1–11.

Conclusions: “Walnut supplementation for 2 y had no effect on cognition in healthy elders. However, brain fMRI and post hoc analyses by site suggest that walnuts might delay cognitive decline in subgroups at higher risk.”

Conflicts of interest: AS-V, SR, JS, and ER have received research funding through their institutions from the California Walnut Commission, Folsom, CA, USA. JS and ER were nonpaid members of the California Walnut Commission Scientific Advisory Council. ER was a paid member of the California Walnut Commission Health Research Advisory Group. JS has received honoraria from the CaliforniaWalnut Commission for presentations. AS-V has received support from the CaliforniaWalnut Commission to attend professional meetings. All other authors report no conflicts of interest.

Comment: Some of the authors of this study work at Loma Linda, a university run by vegetarian Seventh-Day Adventists.  As is unusual for industry-sponsored studies, this one found no delay in cognitive decline among older people eating walnuts.  But the study’s conclusions spin the results to suggest that walnuts might, in fact, delay cognitive decline in higher risk subgroups—an interpretation bias.

Walnuts are good foods and eating them instead of candy or other high calorie junk-food snacks makes sense.  Are walnuts better for you than any other nut?  This study does not address that question.  Studies funded by walnut trade associations have one and only one purpose: marketing walnuts.

As a reminder, I discussed issues related to sponsored research—including why the conduct of the science is not the problem with these studies—in my book, Unsavory Truth: How Food Companies Skew the Science of What We Eat.

I learned about this from a tweet.

I recognized the clip.  It was from an interview I did in January in Toronto: TVO’s The Agenda: Battling bias in nutrition research (slso on YouTube, and in transcript).  Nam was the terrific interviewer.

But do not miss Minhaj’s last Patriot Act episode of 2019, “How America is Causing Global Obesity.”  This is a brilliantly researched account of obesity politics, from food industry influence to trade policy.

I couldn’t have done better myself and dearly wish I had his production team (and his performance ability).