Search results: american journal of clinical nutrition

I’ve posted several studies sponsored by the blueberry industry , most recently on their effects on menopausal symptoms.  Blueberry trade associations, as I discuss in my book Unsavory Truth: How the Food Industry Skews the Science of What We Eat, led the way in promoting research suggesting this fruit is a “superfood.”

If only.

They are still at it, apparently, but sponsorship does not always guarantee the desired outcome.  Here is a rare exception to the rule that industry-sponsored studies almost invariably give results favorable to the sponsor’s marketing interest.  Let’s give credit where it is due.

• The study:  Chronic and postprandial effect of blueberries on cognitive function, alertness, and mood in participants with metabolic syndrome – results from a six-month, double-blind, randomized controlled trial.  The American Journal of Clinical Nutrition.  Available online 6 February 2024, https://doi.org/10.1016/j.ajcnut.2023.12.006
• Methods: “A double-blind, randomized controlled trial was conducted, assessing the primary effect of consuming freeze-dried blueberry powder, compared against an isocaloric placebo, on cardiometabolic health >6 mo and a 24 h postprandial period (at baseline).”
• Results: “Postprandial self-rated calmness significantly improved after 1 cup of blueberries (P = 0.01; q = 0.04; with an 11.6% improvement compared with baseline between 0 and 24 h for the 1 cup group), but all other mood, sleep, and cognitive function parameters were unaffected after postprandial and 6-mo blueberries.”
• Conclusion: “Although self-rated calmness improved postprandially, and significant cognition-metabolite associations were identified, our data did not support strong cognitive, mood, alertness, or sleep quality improvements in MetS participants after blueberry intervention.”
• Conflict of interest: “AC reports financial support provided by the US Highbush Blueberry Council (USHBC) and Biotechnology and Biological Sciences Research Council (BBSRC, UK). AC and EBR both act as advisors and consultants to the United States Highbush Blueberry Council grant committee. All other authors report no conflicts of interest.”
• Funding: “This work was supported by the United States Highbush Blueberry Council with oversight from the USDA and the Biotechnology and Biological Sciences Research Council (United Kingdom). The funders of this research had no involvement in this publication and have placed no restrictions on the publication of these data.”

Comment: In this instance, the last statement could well be correct (it isn’t always, alas).  I like blueberries but they are not a superfood.  There is no such thing as a superfood.  If you want to eat healthfully, by all means eat fruit—and enjoy the ones you like best.

Here’s another one that several readers have asked me about: Multivitamin Supplementation Improves Memory in Older Adults: A Randomized Clinical Trial.  Authors: Lok-Kin Yeung, Daniel M. Alschuler, Melanie Wall, Howard D. Sesso, JoAnn E. Manson, Adam M. Brickman.  American Journal of Clinical Nutrition. DOI:https://doi.org/10.1016/j.ajcnut.2023.05.011

The study: “Participants were randomly assigned to a daily multivitamin supplement (Centrum Silver) or placebo and evaluated annually with an Internet-based battery of neuropsychological tests for 3 y.”  Primary outcome measure: change in episodic memory (immediate recall performance on the ModRey test, after 1 y of intervention).  Secondary outcome measures: changes in episodic memory over 3 y of follow-up,  and in performance on neuropsychological tasks of novel object recognition and executive function over 3 y.

Results: “Compared with placebo, participants randomly assigned to multivitamin supplementation had significantly better ModRey immediate recall at 1 y, the primary endpoint (t(5889) = 2.25, P = 0.025), as well as across the 3 y of follow-up on average (t(5889) = 2.54, P = 0.011). Multivitamin supplementation had no significant effects on secondary outcomes…we estimated that the effect of the multivitamin intervention improved memory performance above placebo by the equivalent of 3.1 y of age-related memory change.”

Conflict of interest: HDS, JEM, and AMB received investigator-initiated grant support to their institutions from Mars Edge. Pfizer Consumer Healthcare (now Haleon) provided support through the partial provision of study pills and packaging. HDS received investigator-initiated grants from Pure Encapsulations and Pfizer Inc and honoraria and/or travel for lectures from the Council for Responsible Nutrition, BASF, NIH, and the
American Society of Nutrition during the conduct of the study. No funding sources had a role in the design and conduct of the study; collection, management, analysis, and interpretation of the data; preparation, review, or approval of the manuscript; and the decision to submit the manuscript for publication.

Funding: This work was supported by an investigator-initiated grant from Mars Edge, a segment of Mars Inc dedicated to nutrition research. Pfizer Consumer Healthcare (now Haleon) provided support through the
partial provision of study pills and packaging.

Comment:  This study continues to surprise me.  As I’ve written before, it is part of the COSMOS trial, which is also supported by grants from NIH and a private foundation.  In my previous post on it, I noted that despite being funded by Pfizer (which makes Centrum Silver multivitamin supplements), the study did not show benefits of the supplement for prevention of cardiovascular disease or cancer—a rare exception to the rule that industry-funded studies tend to favor the sponsor’s interests.  But here we go again, this time with an equally surprising result but for a different reason: most multivitamin studies have shown no benefits whereas this one says if you take Centrum Silver, it will give you another three years of no loss in memory.  Wow!  I’ll be Pfizer is thrilled.

Here’s what the NIH National Center for Complementary and Integrative Health says about multivitamins:

Unprocessed red meat in the dietary treatment of obesity: a randomized controlled trial of beef supplementation during weight maintenance after successful weight loss.  Faidon Magkos, Sidse I Rasmussen, Mads F Hjorth, Sarah Asping, Maria I Rosenkrans, Anders M Sjödin, Arne V Astrup, Nina R W Geiker. The American Journal of Clinical Nutrition, Volume 116, Issue 6, December 2022, Pages 1820–1830, https://doi.org/10.1093/ajcn/nqac152

Methods: In this 5-mo parallel randomized intervention trial, 108 adults with BMI 28–40 kg/m² (45 males/63 females) underwent an 8-wk rapid weight loss period, and those who lost ≥8% body weight (n = 80) continued to ad libitum weight maintenance diets for 12 wk: a moderate-protein diet with 25 g beef/d (B25, n = 45) or a high-protein diet with 150 g beef/d (B150, n = 35).

Conclusions: Healthy diets consumed ad libitum that contain a little or a lot of unprocessed beef have similar effects on body weight, energy metabolism, and cardiovascular risk factors during the first 3 mo after clinically significant rapid weight loss.

Funding: The study was supported by The Beef Checkoff (a program of the National Cattlemen’s Beef Association, CO, USA) and the Danish Agriculture & Food Council (Copenhagen, Denmark). Lighter Life (Essex, UK) sponsored very-low-calorie diet products for the weight-loss phase of the study. The sponsors had no role in study design; in the collection, analysis, and interpretation of data; in the writing of the report; or in the decision to submit the article for publication.

Conflicts of interest: NRWG has received funding from The Beef Checkoff program (National Cattlemen’s Beef Association, CO, USA) and the Danish Agriculture & Food Council (Copenhagen, Denmark) to conduct additional studies relevant to the role of meat in the diet. AVA is a member of the scientific advisory board for Weight Watchers, USA; congressional chairman for RNCP (Répertoire National des Certifications Professionnelles), France; co-owner of the University of Copenhagen spin-off Flax-Slim ApS; co-inventor on a pending provisional patent application for the use of biomarkers to predict responses to weight-loss diets; and co-inventor of other related patents and patent applications that are all owned by the University of Copenhagen, in accordance with Danish law. All other authors report no conflicts of interest.

Comment: The conclusion of this beef industry-funded study is that you can eat as much beef as you like without its having any effect on your body weight or metabolic risk factors, as long as you first lose weight and keep it off.  This is a perfect example of why looking at one food at a time makes no sense without also taking into consideration everything else you are eating and how much.  The Beef Checkoff got the answer it wanted, so money well spent.

So many people send me these things that I can hardly keep up.  Let’s take a look at two this time.  Thanks to Hugh Joseph and Matthew Kirby for these:

I.  The impact of almonds and almond processing on gastrointestinal physiology, luminal microbiology, and gastrointestinal symptoms: a randomized controlled trial and mastication study   Alice C Creedon, Eirini Dimidi, Estella S Hung, Megan Rossi, Christopher Probert, Terri Grassby, Jesus Miguens-Blanco, Julian R Marchesi, S Mark Scott, Sarah E Berry, Kevin Whelan.  The American Journal of Clinical Nutrition, Volume 116, Issue 6, December 2022, Pages 1790–1804, https://doi.org/10.1093/ajcn/nqac265

• Conclusions: “Almond consumption has limited impact on microbiota composition but increases butyrate in adults, suggesting positive alterations to microbiota functionality. Almonds can be incorporated into the diet to increase fiber consumption without gut symptoms.”
• Funding: Supported by an Almond Board of California grant (to KW). The funders provided financial support, and the whole and ground almonds consumed by participants in the trial, but had no role in study design, conduct, analysis, interpretation, or decision to publish.
• Author disclosures: ACC was funded by a PhD studentship funded by Almond Board of California. ED has received an education grant from Alpro, research funding from the British Dietetic Association, Almond Board of California, the International Nut and Dried Fruit Council, and Nestec Ltd, and has served as a consultant for Puratos. MR and KW have received research funding from Almond Board of California, Danone, and International Dried Fruit and Nut Council, and are co-inventors of volatile organic compounds in the diagnosis and dietary management of irritable bowel syndrome. MR is also cofounder of Bio&Me, a gut health food brand. TG supervises PhD students partially funded by Mondelez and McCain Foods Ltd, and has previously received research funding from Almond Board of California. SEB has received grant funding from Almond Board of California, Malaysian Palm Oil Board, and ZOE Ltd, and receives consultancy and options from ZOE Ltd. All other authors report no conflicts of interest.
• Comment: The Almond Board is doing its job, apparently.

II. Almond intake alters the acute plasma dihydroxy-octadecenoic acid (DiHOME) response to eccentric exercise.   David C. Nieman^1*,  Ashraf M. Omar²,  Colin D. Kay³,  Deepak M. Kasote³,  Camila A. Sakaguchi¹,  Ankhbayar Lkhagva²,  Mehari Muuz Weldemariam² and  Qibin Zhang. Front. Nutr., 09 January 2023. https://doi.org/10.3389/fnut.2022.1042719

• Conclusions: “These data support some positive effects of almond intake in improving mood state, retaining strength, decreasing muscle damage, increasing the generation of gut-derived phenolic metabolites, and altering the plasma oxylipin DiHOME response to unaccustomed eccentric exercise in untrained adults. The elevated post-exercise plasma levels of 12,13-DiHOME with almond intake support positive metabolic outcomes for adults engaging in unaccustomed eccentric exercise bouts.”
• Funding: “This work was supported by Almond Board of California, Modesto, CA. The funder had no role in the study design, data collection, analysis and interpretation, the preparation of the manuscript, or in the decision to submit the article for publication.”
• Conflict of Interest: “The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.”
• Comment:  I disagree.  The fact that the Almond Board funded the study if nothing else gives the appearance of conflicted interests, especially because studies so clearly document the influence of funding whether recognized by recipients or not.

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My theme for this week is meat, poultry, and their alternatives, starting today with this:

The study: Unprocessed red meat in the dietary treatment of obesity: a randomized controlled trial of beef supplementation during weight maintenance after successful weight loss.  Faidon Magkos, Sidse I Rasmussen, Mads F Hjorth, Sarah Asping, Maria I Rosenkrans, Anders M Sjödin, Arne V Astrup, Nina R W Geiker.  The American Journal of Clinical Nutrition, nqac152, https://doi.org/10.1093/ajcn/nqac152.  

Objectives: “We sought to investigate the effects of healthy diets that include small or large amounts of red meat on the maintenance of lost weight after successful weight loss….”

Several people sent me this one:

Prunes preserve hip bone mineral density in a 12-month randomized controlled trial in postmenopausal women: the Prune Study.  The American Journal of Clinical Nutrition,  nqac189, https://doi.org/10.1093/ajcn/nqac189

Conclusions: A 50g daily dose of prunes can prevent loss of total hip BMD [bone mineral density] in postmenopausal females after six months, which persisted for 12-months…we propose that the 50g dose represents a valuable non-pharmacological treatment strategy that can be used to preserve hip BMD in postmenopausal females and possibly reduce hip fracture risk

Sources of Support: California Prune Board (Award Number: 180215)

Acknowledgments: We thank the California Prune Board for the funding and prunes…The California Prune Board had no role in the data collection and analysis, decision to publish, or preparation of manuscript.in this study.

Comment: The California Prune Board did not have to have that kind of role to get the outcome it wanted.  Research on funding effects shows that industry influence is exerted primarily in the ways the research question is framed and the results interpreted.  It also shows that investigators hardly ever recognize how industry funding exerts influence.

Reference:  Unsavory Truth: How Food Companies Skew the Science of What We Eat.

Thanks to a reader in Israel, Yehuda Ben-Hur, for sending this one.

The study: The effect of a high-polyphenol Mediterranean diet (Green-MED) combined with physical activity on age-related brain atrophy: the Dietary Intervention Randomized Controlled Trial Polyphenols Unprocessed Study (DIRECT PLUS) .  Alon Kaplan, Hila Zelicha, Anat Yaskolka Meir, Ehud Rinott, Gal Tsaban, Gidon Levakov, Ofer Prager, Moti Salti, Yoram Yovell, Jonathan Ofer, Sebastian Huhn, Frauke Beyer, Veronica Witte, Arno Villringer, Nachshon Meiran, Tamar B Emesh, Peter Kovacs, Martin von Bergen, Uta Ceglarek, Matthias Blüher, Michael Stumvoll, Frank B Hu, Meir J Stampfer, Alon Friedman, Ilan Shelef, Galia Avidan, Iris Shai.  The American Journal of Clinical Nutrition, nqac001, https://doi.org/10.1093/ajcn/nqac001 Published: 11 January 2022.

Objectives: We aimed to explore the effect of a Mediterranean diet (MED) higher in polyphenols and lower in red/processed meat (Green-MED diet) on age-related brain atrophy.

Methods:  Abdominally obese  participants were randomly assigned to follow one of three diets: (1) healthy dietary guidelines (HDG), (2) MED, or (3) Green-MED diet.  The two MED groups consumed 28 g walnuts/d.  The Green-MED group consumed green tea , mankai (100 g frozen cubes/d as a green shake).  After 18 months, participants got MRI scans.

Results: Indicators of brain atrophy were attenuated in both MED groups, with the best outcomes among Green-MED diet participants.  Therefore, greater Mankai, green tea, and walnut intake and less red and processed meat were significantly and independently associated with reduced atrophy decline .

Conclusions: A Green-MED (high-polyphenol) diet, rich in Mankai, green tea, and walnuts and low in red/processed meat, is potentially neuroprotective for age-related brain atrophy.

Funding: Supported by German Research Foundation, Israel Ministry of Health, Israel Ministry of Science and Technology, and the California Walnut Commission (to I Shai, the senior author). “None of the funding providers were involved in any stage of the design, conduct, or analysis of the study, and they had no access to the study results before publication.”

Comment: I hardly know what to make of this study, which involves so many variables: mankai, (duckweed, supposedly a polyphenol-rich “supergreen”), green tea, walnuts, and low red/processed meat.  The MED groups were instructed to consume a calorie-restricted Mediterranean diet “rich in vegetables, with poultry and fish partly replacing beef and lamb.”  Physical activity instructions (and gym memberships) as well nutrition counseling was also part of this mix.

My questions:

• Why not test the Mediterranean diet on its own without all those polyphenol additives?
• Why walnuts as opposed to any other polyphenol-containing food?  Could sponsorship have anything to do with this choice?
• Why Mankai, which is traditionally a component of Asian diets, not Mediterranean?    Why are Israeli scientists so interested in this plant?
• Don’t classic Mediterranean diets provide enough polyphenols to be protective against brain atrophy?

I will be intersted to see further studies along these lines.

I like French fries as much as anyone but c’mon; they are hardly a health food.

The Alliance for Potato Research & Education sent me a press release about a new study demonstrating that “adding a daily 300-calorie serving of French fries to one’s typical diet every day for one month does not result in differential short-term weight gain or other biomarker changes associated with impaired blood sugar regulation compared to adding an isocaloric daily serving of almonds.”

The study: French-fried potatoes consumption and energy balance: a randomized controlled trial.  Daniel L Smith, Jr, Rebecca L Hanson, Stephanie L Dickinson, Xiwei Chen, Amy M Goss, John B Cleek, W Timothy Garvey, David B Allison.  The American Journal of Clinical Nutrition, nqac045, https://doi.org/10.1093/ajcn/nqac045

Purpose: “We completed an RCT [randomized controlled trial] testing whether increased daily potato consumption influences energy balance (specifically, fat mass (FM)) compared with calorie-matched almond consumption.”  Participants were given 300 calories a day in either fries (~3 oz) or almonds (~40).

Conclusion: There were no significant differences in FM [fat mass] or in glucoregulatory biomarkers after 30 days of potato consumption versus almonds. Results do not support a causal relationship between increased French fried potato consumption and the negative health outcomes studied.

Funding: This study was supported in part by a grant from the Alliance for Potato Research and Education (APRE) to DBA and DLS, by Core services through NIH grant awards P30DK056336 and P60DK079626 and the donation of study food items by J.R. Simplot Company.

Comment:  I’m not surprised by this result.   Biomarkers depend on everything you eat, not just one food.

The purpose of this study was to take away any guilt you might feel about eating French fries.   The potato alliance got the result it wanted.