Search results: research bias

Conclusions and Relevance  In this randomized clinical trial, we observed cardiometabolic advantages for the healthy vegan vs the healthy omnivorous diet among healthy, adult identical twins. Clinicians may consider recommending plant-based diets to reduce cardiometabolic risk factors, as well as aligning with environmental benefits.

The study has its share of detractors, American Council on Science and Health (ACSH), for example: Stanford Medicine Releases Confirmation Bias Study; Media Takes The Bait.  Its chief criticisms

• The improvements were in biomarkers, not health.
• Both diets were healthy,
• Obviously, diets without cholesterol will reduce cholesterol.
• Vitamin B12 levels were ldeficient on the vegan diet.

Comment: The ACSH is an industry-funded front group.  Low B12 is an easy problem to solve, and vegans, who by definition eat no foods of animal origin, have to make sure they complensate for its absence.

The twin idea is clever and adorable—and the reason for the press attention and for the Netflix documentary.  The study shows that vegan diets improve cardiovascular risk biomarkers in healthy people.  Why not?  This is further evidence for the benefits of largely plant-based diets.

For years now I have been posting on Mondays something about conflicts of interest in nutrition research and practice on this site .

My goal in doing so is to raise awareness of practices that give the nutrition profession the appearance of undue food industry influence at the expense of public health.

Occasionally someone involved with something I post requests a correction or clarification.

Most recently, I heard from Gunter Kuhnle, a researcher in the UK whom I do not know personally.   He wrote:

In your blog (https://www.foodpolitics.com/2023/11/chocolate-an-update-on-the-food-politics-thereof/), you comment about my article in “The Conversation” on flavanols. This comment concludes with a statement that could be interpreted as if I was paid to write this piece. I would like to make clear that I was not paid to write this article – it was conceived and written in order to address a number of misunderstandings in the reporting of various studies concerning flavanols.  I would appreciate if you could correct this.

Since that was not at all my intention, I clarified the post immediately.

But I also requested his permission to reprint his note so I could do some more explaining about why this issue so concerns me.

I want to start by emphasizing that I do not see this as a personal matter.  My original post did not mention the author’s name and in general I try to avoid mentioning names of authors of industry-funded research unless they report financial ties to companies with vested interests in the outcome of that research.

I see this as a systemic issue.

But to summarize the arguments—and the research—I make and summarize in my book, Unsavory Truth: How Food Companies Skew the Science of What We Eat:

An enormous body of evidence, most of it derived from studies of tobacco, chemical, or pharmaceutical drug industry-sponsored research, consistently shows:

• Industry-funded research generally yields results that favor the sponsor’s interests.
• Industry funding of research influences its outcome.
• The influence of industry funding usually shows up in the framing of the research question or in the interpretation of results.
• Recipients of industry funding do not recognize the influence, do not intend to be influenced, and deny the influence (“science is science”).
• Denial of influence contradicts an enormous body of evidence to the contrary.
• Disclosure of funding source or relationships is necessary but not sufficient; considerable evidence exists to show that the statement “the sponsor had nothing to do with the design, conduct, or publication of the study” is often misleading or false.
• Exceptions do exist, but they are rare.

That researchers do not recognize the risks of industry funding is disturbing.  At the very least, when nutrition researchers accept funding from food companies, they give the appearance of conflict of interest.

And that is all it takes to reduce public trust in nutrition research, nutrition professionals, and nutrition professional societies.

I think there is something seriously wrong when I can look at the title of a nutrition research article and make a good guess about what company or industry trade association funded it.

I think there is something seriously wrong when I can look at the funder of a study and guess what the outcome is.

One more point: an argument I hear often is that all nutrition researchers are biased because they have dietary or ideological preferences.  There is research on this point too.  It argues that all researchers have personal or ideological biases—that’s what motivates them to do studies to test their hypotheses.  Personal biases, therefore, are universal and do not cause conflicts of interest.

Industry funding introduces a quite different motive: proving the health benefits or safety of a food product for commercial—not scientific—purposes.

Unsavory Truth provides references for all of this.

Also see Science in the Private Interest:  Has the Lure of Profits Corrupted Biomedical Research? by the late Sheldon Krimsky (I miss him terribly).

Professor Kuhnle, I thank you for writing and for the opportunity to respond.

I received an emailed press release from Gary Ruskin at US Right to Know: Report: Nearly Half of Dietary Guidelines Advisory Committee Have Conflicts of Interest.

Nine out of 20 members of the Dietary Guidelines Advisory Committee have conflicts of interest with food, pharmaceutical, or weight loss companies or industry groups with a stake in the outcome of the guidelines, according to a new report published today by the nonprofit public health research group U.S. Right to Know. An additional four members had possible conflicts of interest. The report found that Abbott, Novo Nordisk, National Dairy Council, Eli Lilly, and Weight Watchers (WW) International had ties to two or more DGAC members.

My immediate reaction: Only 9?  Last time, it was 19 out of 20.

Some background

The agencies responsible for the guidelines, HHS and USDA, issued aggregated disclosures of committee members relationships with industry. These treated real conflicts (Mars, Egg Nutrition Center, Novo Nordisk) with non-conflicts (National Science Foundation, Ohio Department of Medicaid) as if they were equivalent; they are not.

The sponsoring agencies have always argued that it is impossible to find nutrition experts without industry ties.  I disagree.  It’s just that people like me who are careful to avoid industry ties are considered too biased to serve on such committees (or so I’ve been told, repeatedly—I’ve not been asked to serve on a federal committee since Food Politics came out).

Do industry ties influence the report?  This is less of a problem than it used to be.  When I was on the DGAC in 1995, our committee set the research questions, did the research, wrote the research report, and wrote the actual Dietary Guidelines.  The agencies did light editing.

That changed in 2010 (administration of Bush II) when the agencies took over writing the guidelines.

In 2020, the agencies wrote the research questions, and they did so again this round.

This means that the only thing left for the DGAC to do is to review the research on questions determined by the agencies.

What is US Right to Know?

This group has initiated and “co-authored 15 peer-reviewed public health studies revealing how the food and beverage industries and industry-funded groups try to influence public opinion, scientific research, public health conferences and government policies related to diet and nutrition.”

A reader, Leah Murphy, wrote me questioning USRTK’s funding (see Appendix D in the report).

“Funding for the report was provided by Feed the Truth, a 501c3 non-profit that is funded by the Lubetzky Family Foundation.”

Daniel Lubetzky is the founder of KIND, a food company.  My point is that a food company funds the non-profit that funded the report. And that seems to undermine the credibility of their report and could qualify under their definition as a COI.

Ordinarily, I would agree that this could be a problem, but not in this instance.  In a previous post on Feed the Truth, I say:

 I was part of a team that suggested names for members of the group’s board.  Once Lubetzky set up the funding, he has had nothing further to do with the group.

From what I’ve been told, that is still true.  Feed the Truth does not have a website, in part because it is closing shop and not giving out more grants.  You can read about its earlier stages in Influence Watch,  Cause IQ, and Cision PR Newswire, but these are now out of date.

USRTK is doing important work and lots of it.  It’s worth following it.

Resources

• The report: Full Disclosure: Assessing Conflicts of Interest of the 2025 Dietary Guidelines Advisory Committee.
• The Guardian: US nutrition panel’s ties to top food giants revealed in new report
• The BMJ: US dietary committee is plagued with “high risk conflicts of interest,” report finds.
• The New York Times: Food Industry Influence Could Cloud the U.S. Dietary Guidelines, a New Report Says (I’m quoted)

I have been sent so many examples of industry-funded studies that I can’t keep up with them.  This is a slow news week and I’m traveling, so how about I post several.  Here’s the first.

My thanks to Katie Iwanowski for sending this one.

The study: The Relationship of Ready-to-Eat Cereal Intake and Body Weight in Adults: A Systematic Review of Observational Studies and Controlled Trials Lisa M. Sanders, Mary R. Dicklin, Yong Zhu, Kevin C. Maki.  Advances in Nutrition, Volume 14, Issue 4, 2023, Pages 671-684.  https://doi.org/10.1016/j.advnut.2023.05.001.

Results:  RTEC[Ready to Eat Cereal] consumers (2 – 4 servings a week), as compared with non- and less frequent consumers have lower BMI, lower prevalence of overweight/obesity, less weight gain over time,  less anthropometric evidence of abdominal adiposity.

Conclusions:

• RTEC may be used as a meal or snack replacement as part of a hypocaloric diet, but this approach is not superior to other options for those attempting to achieve an energy deficit.
• RTEC consumption was not associated with significantly less loss of body weight, or with weight gain, in any of the RCTs.
• RTEC intake is associated with favorable body weight outcomes in adults in observational studies.
• RTEC does not hinder weight loss when used as a meal or snack replacement within a hypocaloric diet.

Funding: This research was funded by Bell Institute of Health and Nutrition, General Mills Inc. The funding sponsor commented on the study design’s early aspects, reviewed the final data, and provided input to the manuscript.

Author disclosures: LMS is a consulting scientist, and MRD and KCM are employees of Midwest Biomedical Research, which has received research funding from General Mills Inc and Kellogg Company. LMS has received funding from Kellogg Company. YZ is an employee of General Mills Inc.

Comment: This cereal study was funded by a cereal company which—this is quite unusual—disclosed its involvement in the study’s design, interpretation, and writing.  The study results are a classic example of interpretation bias.  Basically, breakfast cereals don’t make much difference to body weight (it’s overall calorie balance that counts), but the conclusions are spun positively.  I especially like the double negative, “not associated with significantly less loss….”

The U.K.’s Scientific Advisory Committee on Nutrition (SACN) has released its statement on ultra-processed foods.

It dealt with the NOVA classification system (the one I used in yesterday’s post to define ultra-processed foods).  The committee does not like it much.

Assessment beyond the initial screen identified that the literature is currently dominated by NOVA, raising the risk that any limitations or biases present within the NOVA classification system may be replicated throughout the research literature.
While NOVA also met criterion 2 on a clear, usable definition and criterion 4 on the availability of data on inter-assessor agreement, assessment beyond the initial screen dentified less certainty on the clarity, reliability and feasibility of the system.

The SACN’s conclusions:

The SRs identified have consistently reported that increased consumption of (ultra-) processed foods was associated with increased risks of adverse health outcomes. However, there are uncertainties around the quality of evidence available. Studies are almost exclusively observational and confounding factors or key variables such as energy intake, body mass index, smoking and socioeconomic status may not be adequately accounted for.

…In particular, the classification of some foods is discordant with nutritional and other food-based classifications. Consumption of (ultra-) processed foods may be an indicator of other unhealthy dietary patterns and lifestyle behaviours. Diets high in (ultra-) processed foods are often energy dense, high in saturated fat, salt or free sugars, high in processed meat, and/or low in fruit and vegetables and fibre.

…The observed associations between higher consumption of (ultra-) processed foods and adverse health outcomes are concerning – however, the limitations in the NOVA classification system, the potential for confounding, and the possibility that the observed adverse associations with (ultra-) processed foods are covered by existing UK dietary recommendations mean that the evidence to date needs to be treated with caution.

Comment: Kevin Hall  et al’s well controlled clinical trial of ultra-processed versus merely processed diets is neither discussed nor cited in this statement.  Once again, I have no personal knowledge of how this statement was developed, but the U.K.s Soil Association has published a statement with the provocative title, Sticky fingers of food industry on government ultra-processed food review.

While we’re pleased that SACN has prioritised this review, and has acknowledged that ultra-processed foods are of “concern”, we’re disturbed that the committee’s conclusions may have been skewed by industry ties, conflicted financial interests, and a narrow framing of the science.

…But the committee is also guilty of losing the wood for the trees, failing even to raise concern about how ultra-processed foods have overtaken their own nutritional advice….Most people in the UK are failing to eat such a [healthy] diet, precisely because these foods have been displaced by ultra-processed products. The average child’s diet is more than 60% ultra-processed, and rates of obesity and ill health are rising sharply in turn. …SACN is oddly silent on case for re-balancing the diet and addressing the corporate capture of children’s food.

These omissions should prompt us to look more closely at the composition of the committee. SACN has sixteen members. One is a paid consultant working for Cargill, Tate & Lyle, and CBC Israel (a manufacturer and marketer of fizzy drinks such as Coca-Cola and Sprite); two are in receipt of funding from the meat and dairy industry; one is a shareholder in Sainsbury’s; and five are members of the American Society of Nutrition, which is funded by Mars, Nestlé, and Mondelez. Among SACN’s members is the Chair of International Life Sciences Institute (ILSI) Europe, a body that receives funding from some of the world’s largest food companies, such as Barilla, Cargill, Danone, General Mills, Mondelez, and PepsiCo; and two individuals with financial relationships with the British Nutrition Foundation, an organisation funded by British Sugar, Cargill, Coca Cola, Danone, Greggs, Kellogg, KP Snacks, Mars, McDonald’s, Mondelez, Nestlé, PepsiCo, Tate & Lyle, and Tesco. Two SACN members have been funded by Danone, one of the largest ultra-processed food companies in the world; one sits on the council of the Nestlé Foundation; and another is a former employee of Unilever, with current shares in the company worth “more than £5000”.

These declared interests do not imply corruption or bias on the part of SACN members, but they illustrate how pervasive are industry ties at the interface of science and policy.

In a strange partnership, the Nutrition Coalition and the Center for Science in the Public Interest (CSPI) are jointly complaining about the way the USDA and HHS have “disclosed” conflicts of interest among members of the 2025-2030 Dietary Guidelines Advisory Committee.

Why strange?  Because the Nutrition Coalition has long urged relaxations on advice about dietary fat, whereas CSPI has long urged restrictions.

Why “disclosed” in quotes?  Because the agencies’ disclosure statement lists the combined conflicts for the entire group, not for individual members of the committee.

Here’s the committee, courtesy of a tweet from Christopher Gardner.

Dietary Guidelines Advisory Committee

2nd in person meeting of DGAC this week.
Committee members are a pleasure to work with – thoughtful, critical, informed group.

HHS/USDA staff supporting the effort are an incredible resource! Wow!

2-year process is off to a great start! pic.twitter.com/6Cx5npxJcH

— Christopher Gardner (@GardnerPhD) May 13, 2023

Here is a small part of what the disclosure list looks like.

Because these are all jumbled together, you have to look hard to pull out the genuine conflicts—-relationships of committee members with food companies with vested interests in the outcome of the guidelines.

The Nutrition Coalition points out that USDA and HHS are failing to:

• Comply with a National Academies of Science report calling for publicly posting financial and nonfinancial biases and conflicts of interest of committee members.
• Fully adopt the National Academies’ 11 recommendations.
• Recognize the significance of the first-ever systematic review of a DGAC’s financial ties. This review found 95% of the 2020 DGAC members had at least one tie with a food or pharmaceutical company and half had 30 such ties or more.

In its statement, CSPI says that it, the Coalition, and 13 other groups are calling on the federal government to disclose potential financial conflicts of interest, including sources of research funding, speakers’ fees, and other relationships.

Press coverage, the statement says, “has already uncovered one 2025 Dietary Guidelines Advisory Committee member with a conflict of interest that seems relevant to their role.”

Comment:  I agree that the credibility of the committee and the guidelines depends on transparency, but it’s hard to know how much of a problem this is.

I wanted to compare the disclosure list to the research questions set by the agencies for the committee, but I can no longer find them online.

This reminds me that’s it’s hard to know how much influence the committee will have, in any case, now that the agencies set the research questions and write the actual guidelines.

The advisory committee is just that, advisory.  The agencies do not have to take its advice.

I will be following this closely.  Stay tuned.

Additions, May 17 (thanks to Jerry Mande)

• The original list of Proposed Scientific Questions
• The list as posted on the current website: Step 3: Advisory Committee Reviews Scientific Evidence

NutraIngredients, a newsletter I read daily, caught my eye with this headline:

Blueberries benefit postmenopausal women with high blood pressure: Study:  Daily blueberry consumption improves endothelial function in postmenopausal women with high blood pressure, according to a recent study…. Read more

I looked it up, of course.

• The study: Daily blueberry consumption for 12 weeks improves endothelial function in postmenopausal women with above-normal blood pressure through reductions in oxidative stress: a randomized controlled trial. Food Funct., 2023,14, 2621-2641
• Objective: “to examine the efficacy of blueberries to improve endothelial function and blood pressure in postmenopausal women with above-normal blood pressure, and to identify potential mechanisms for improvements in endothelial function.”
• Method: Postmenopausal women with elevated blood pressure or hypertension were given 22 g/day of freeze-dried highbush blueberry powder or placebo powder for 12 weeks.
• Findings: The sum of plasma (poly)phenol metabolites increased in the blueberry group compared to baseline, and were higher than the placebo group.  Increases in several plasma flavonoid and microbial metabolites were also noted. No major differences were found for blood pressure, arterial stiffness, blood biomarkers, or endothelial cell protein expression following blueberry consumption (my emphasis).
• Conclusion: “These findings suggest daily consumption of freeze-dried blueberry powder for 12 weeks improves endothelial function through reduced oxidative stress in postmenopausal women with above-normal blood pressure”
• Conflicts of interest: There are no conflicts to declare.
• Acknowledgements: This research was funded by the US Highbush Blueberry Council, the USDA National Institute of Food and Agriculture [Grant No. 2020-67017-30833/Project Accession No. 1021875], and the College of Health and Human Sciences at Colorado State University.

Comment: Yes there is a conflict of interest, but the authors don’t seem to recognize it.  This is a classic case of interpretation bias; the study didn’t show much of anything but the authors conclude that blueberry powder does some good.

High marks to NutraIngredients for disclosing the funding source right at the top of the article:

Published in the journal Food and Function, the study was supported by the US Highbush Blueberry Council and the USDA National Institute of Food and Agriculture.

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I always enjoy the Headline vs Study section of the newsletter, Obesity and Energetics Offerings.

• Headline: Healthy New Brain Food for Stressed University Students.
• RCT: No Significant Walnut-Versus-Control Effects Reported for the Primary 16-Week Outcomes of Profile of Mood States (POMS), Salivary Cortisol, or Brain-Derived Neurotrophic Factor.
• Trial Registration: The Effects of Walnuts on General Well­being and Mood Related Factors in a Sample of University Students.

I particularly like this one because the headline says one thing but the study says another, and the authors put a positive spin on the results (interpretation bias).

The study: The Effects of Walnuts and Academic Stress on Mental Health, General Well-Being and the Gut Microbiota in a Sample of University Students: A Randomised Clinical Trial.  Nutrients 2022, 14(22), 4776; https://doi.org/10.3390/nu14224776

Rationale: Poorer mental health is common in undergraduate students due to academic stress. An interplay between stress and diet exists, with stress influencing food choices.

Results: Academic stress was associated with lower gut microbial diversity in females, which was improved by walnut consumption.  The effects of academic stress or walnut consumption in male participants could not be established due to small numbers of participants. Thus, walnut consumption may have a protective effect against some of the negative impacts of academic stress, however sex-dependent mechanisms require further study.

Overall conclusion: While daily consumption of walnuts could not alleviate disturbances in mood, it had a protective effect against the negative impacts of academic stress on mental health…daily walnut consumption over 16 weeks was able to alleviate the negative effects of academic stress on the diversity of the gut microbiota in females, however the relevance of these changes to the biochemistry of chronic stressors such as academic stress requires further study.

Funding: This research was co-funded by the University of South Australia (UniSA) and the California Walnuts Board & Commission…Walnuts for the study participants were provided by the California Walnuts Board & Commission. ..We thank Walnuts Australia for providing walnuts to the control group (upon completion of the study)….

Conflicts of interest: The sponsors had no role in the design, execution, interpretation, or writing of the study. The authors declare no conflict of interest.

Comment: The study didn’t show much, despite the enormous amount of work that went into it.  This looks like an excellent example of interpretation bias—putting a positive spin on barely significant results.  Industry-funded research usuall gets interpreted positively and recipients of industry funding believe that it does not influence them or cause conflicted interests.  But much research says it does.  And then, of course, this is a study of the effects of one food, usually not eaten in large amounts (nuts are expensive!) in diets containing large numbers of other foods.  Attributing big health effects to any one food hardly ever makes sense.

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