Currently browsing posts about: Nuts

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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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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As regular readers know, I subscribe to the weekly newsletter, Obesity and Energetics Offerings, and particularly enjoy its section on Headline vs Study.

Here’s a particularly amusing example, which right away triggers my question: Who paid for this?

Headline vs Study

• Headline: Snacking on Almonds Can Help People Reduce Calorie Intake: Study.  
• Press Release: Believe It or ‘Nut’, Almonds Can Help You Cut Calories, Study Finds.  
• Study: “There was no significant difference in total energy intake ([…] p = 0.286) or energy from core ([…] p = 0.860) or discretionary foods ([…] p = 0.158) between [almonds and an isocaloric carbohydrate-rich snack bar].”

Let’s take a look.

Headline: Snacking on Almonds Can Help People Reduce Calorie Intake: Study.

A handful of almonds may be the latest weight loss hack, new research suggests.

A new study from the University of South Australia found that eating 30 to 50 grams of almonds could regulate appetite, leading to less calories consumed each day.

The research, which examined both the hormones that regulate appetite and how almonds could aid in controlling hunger, discovered that the consumption of the nut ultimately led to about 300 fewer calories [sic*]consumed at the following meal.

Press Release: Believe It or ‘Nut’, Almonds Can Help You Cut Calories, Study Finds.

Examining how almonds can affect appetite, researchers found that a snack of 30-50 grams of almonds could help people cut back on the number of kilojoules they consume each day.

Published in the European Journal of Nutrition, the study found that people who consumed almonds — as opposed to an energy-equivalent carbohydrate snack — lowered their energy intake by 300 kilojoules (most of which came from junk food) at the subsequent meal.

Study:  Acute feeding with almonds compared to a carbohydrate-based snack improves appetite-regulating hormones with no effect on self-reported appetite sensations: a randomised controlled trial. Carter, S., Hill, A.M., Buckley, J.D. et al.Eur J Nutr (2022). https://doi.org/10.1007/s00394-022-03027-2

Results: “…Cholecystokinin, ghrelin, glucagon-like peptide-1, leptin and polypeptide YY AUCs were not different between groups. Self-reported appetite ratings and energy intake following the buffet did not differ between groups.”

Conclusion: “More favourable appetite-regulating hormone responses to AL did not translate into better self-reported appetite or reduced short-term energy consumption. Future studies should investigate implications for longer term appetite regulation.”

Funding: “This work was funded by the Almond Board of California. This funding source had no role in the design of this study or the analysis and interpretation of the data.”

Conflict of interest: “AMC has consulted for Nuts for Life (an initiative of the Australian Tree Nut Industry). S-YT has previously been involved in studies funded by the Californian Walnut Commission. AMC, JDB and S-YT have previously been involved in studies funded by International Nut and Dried Fruit Council.”

*Comment: How could the headline get it so wrong?  The authors write: “Although not significant, the AL group consumed 300 kJ less energy in the meal challenge than the SB group, 270 kJ of which came from discretionary foods, which may be a clinically important benefit in weight management.”  The sic partly explains the problem.  The 300 refers to kilojoules (kj), not calories.  300 kj = 72 calories, not 300.  No wonder the result wasn’t statistically significant.

But the press release and resulting headline explain why the nut industry funds studies like this.  Even when the result shows no difference, the PR people can spin the data to produce the expected favorable result.

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I haven’t posted anything about pistachio industry conflicts of interest since 2019 so it’s time for another one.

Here’s a press release sent to me by a reader, Matthew Kadey:

NEW STUDY REVEALS PISTACHIOS ARE AN ANTIOXIDANT POWERHOUSE…Antioxidant-rich foods are regularly encouraged as part of a healthy lifestyle, and research suggests that a diet high in antioxidants may even help to reduce the risk of death.¹ While certain fruits and vegetables are often thought of as high-antioxidant foods, a new study conducted by Cornell University and published in the journal, Nutrients, produced surprising results². Pistachios have a very high antioxidant capacity, among the highest when compared to values reported in research of many foods commonly known for their antioxidant capacity, such as blueberries, pomegranates, cherries, and beets.^3,4,5  (I’ve posted the references at the end).

My first question, as always when I see a press release like this: Who paid for it?

The study: uan, Wang, Bisheng Zheng, Tong Li, and Rui Hai Liu. 2022. Quantification of Phytochemicals, Cellular Antioxidant Activities and Antiproliferative Activities of Raw and Roasted American Pistachios (Pistacia vera L). Nutrients 14, no. 15: 3002. https://doi.org/10.3390/nu14153002

Conclusion:  It is shown that the roasting of pistachios could produce a series of beneficial phytochemical changes, leading to enhanced biological activity. Pistachios are a nutrient-dense food containing a unique profile of good-quality protein, fats, minerals, vitamins, and antioxidants, such as carotenoids and polyphenols, with cellular antioxidant activity. Dietary Guidelines for Americans 2020–2025 suggested including nuts as a health dietary pattern. Further research on antiproliferative activity and mechanisms of action of free-form extracts of roasted pistachios, and more biological activities related cellular antioxidant activity and oxidative stress, are worthy of further investigation.

Funding: This study was partially supported by Innovative Leading Talents Project of Guangzhou Development Zone and 111 Project: B17018, Cornell China Center, and American Pistachio Growers: 2021-09.

Conflicts of Interest: The authors declare no conflict of interest.

Comment: Roasted pistachios are healthy?  No surprise here.  Further research needed?  Also no surprise.  This is another example of an industry-funded study with unimpressive results but plenty of interpretation bias, along with the usual contention that industry funding does not induce conflicts of interest.  Alas, it does.

References to the press release paragraph

¹ Jayedi A, Rashidy-Pour A, Parohan M, Zargar MS, Shab-Bidar S. Dietary Antioxidants, Circulating Antioxidant Concentrations, Total Antioxidant Capacity, and Risk of All-Cause Mortality: A Systematic Review and Dose-Response Meta-Analysis of Prospective Observational Studies. Adv Nutr. 2018 Nov 1;9(6):701-716. doi: 10.1093/advances/nmy040. PMID: 30239557; PMCID: PMC6247336.
² Yuan W, Zheng B, Li T, Liu RH. Quantification of Phytochemicals, Cellular Antioxidant Activities and Antiproliferative Activities of Raw and Roasted American Pistachios (Pistacia vera L.). Nutrients. 2022; 14(15):3002. https://doi.org/10.3390/nu14153002
³ Wolfe KL, et al. Cellular Antioxidant Activity (CAA) Assay for Assessing Antioxidants, Foods, and Dietary Supplements. J Agric. Food Chem. 2007, 55, 8896–8907.
⁴ Song W, et al. Cellular Antioxidant Activity of Common Vegetables. J. Agric. Food Chem. 2010, 58, 6621–6629. DOI:10.1021/jf9035832
⁵ Wolfe, K., Kang, X., He, X., Dong, M., Zhang, Q., and Liu, R.H. Cellular antioxidant activity of common fruits. J. Agric. Food Chem. 56 (18): 8418-8426, 2008.

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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.

Two studies of the role of nuts in health.

I.  This one comes from ObesityandEnergetics.org’s “Headline vs. Study.”

Headline: Maximum Wellness: Walnuts are a Life-Extension Food:  “Looks like your [sic] nuts not to include walnuts in your diet. For more information and to read this study…go to maxwellnutrition.com, where you can find top wellness and nutrition products made in the United States – shipped to your door.”  [Comment: Clearly, we are dealing here with marketing]

Study: Association of Self-Reported Walnut Consumption with Total and Cause-Specific Mortality and Life Expectancy in U.S. Adults. Maximum Wellness nor Causation Necessarily Established.  Liu, X.; Guasch-Ferré, M.; Tobias, D.K.; Li, Y.  Nutrients 2021, 13, 2699. https://doi.org/ 10.3390/nu13082699

Conclusion: A greater life expectancy at age 60 (1.30 years in women and 1.26 years in men) was observed among those who consumed walnuts more than 5 servings/week compared to non-consumers.  Higher walnut consumption was associated with a lower risk of total and CVD mortality and a greater gained life expectancy among U.S. elder adults.  [Comment: association, not causation, and the difference is small].

Conflict of interest: The last (senior?) author reports having received research support from California Walnut Commission, but states that ” The funder has no role in the design and conduct of the study, in the collection, analysis, and interpretation of the data, and in the preparation, review, or in the decision to publish the results.”  [Comment: That’s what they all say, but research often demonstrates otherwise, as I review in my book Unsavory Truth].

And now for the second:

II.  Association of nut consumption with risk of total cancer and 5 specific cancers: evidence from 3 large prospective cohort studies.  Zhe Fang, You Wu, Yanping Li, Xuehong Zhang, Walter C Willett, A Heather Eliassen,1Bernard Rosner,
Mingyang Song, Lorelei A Mucci,and Edward L Giovannucci.  The American Journal of Clinical Nutrition, Volume 114, Issue 6, December 2021, Pages 1925–1935, https://doi.org/10.1093/ajcn/nqab295

Conclusion: In 3 large prospective cohorts, frequent nut consumption was not associated with risk of total cancer and common individual cancers.  [Comment: What? An industry-funded study that finds no benefuts?]

Funding: Supported by the California Walnut Commission and Swiss Re Management Ltd (to YL),… and NIH grants U01 CA167552 (to LAM and the Health Professionals Follow-up Study), UM1 CA186107 and P01 CA87969 (to the Nurses’ Health Study), and U01 CA176726 (to AHE and the Nurses’ Health Study II). The funding sources did not participate in the study design; or
collection, analysis, or interpretation of the data; or preparation, review, or approval of the manuscript.

Here’s how the authors explain their highly unusual no-benefit result:

Given the scarcity of available high-quality data, our findings add to current evidence to more precisely determine the relation between nut consumption and cancer risk. So far, the population based evidence has not been strong enough to conclude that nut consumption is protective against total cancer and these 5 common cancers. Future studies on other cancer sites are still needed to examine the benefits of nuts on cancer development.

Really?  Why?  Do the authors not believe their own data?  Their findings ought to settle the matter and encourage the authors to move on to more significant research.  “More research needed” keeps the California Walnut Commission busy.

Research funded by food companies always requires a degree of skepticism, no matter what the results.

I learned about this one from an article in FoodNavigator: Study: Walnut consumption linked to improved life expectancy

New research from the Harvard T.H. Chan School of Public Health funded by the California Walnut Commission has found a possible link between higher walnut consumption and increase in life expectancy among older US adults.

The article quotes the senior author:

What we’ve learned from this study is that even a few handfuls of walnuts per week may help promote longevity, especially among those whose diet quality isn’t great to begin with. It’s a practical tip that can be feasible for a number of people who are looking to improve their health, which is top of mind for many people.

Washington Post columnist Tamar Haspel tweeted about this study: “I have a pretty big beef with nutritional epidemiology, and there’s a new study on walnuts that pushes all my button[s].”

Her beefs:

• Difficulties interpreting information from food frequency questionnaires
• Complications of correcting for confounding variables (18 in this case)
• Implications of causation (“lots of talk about the cardioprotective aspects of walnuts”)
• The study was not pre-registered
• It was funded by the walnut industry

Her view (with which I concur):

• “Studies like the [sic] have helped create the mess that is nutrition advice”
• “We DO NOT have the tools to assess the health impact of specific foods.”
• “Eat a wide variety of whole-ish foods you enjoy in quantities consistent with the weight you want to be.  Eat walnuts if you like them.”

The study: Association of Walnut Consumption with Total and Cause-Specific Mortality and Life Expectancy in U.S. Adults.  Xiaoran Liu, Marta Guasch-Ferré, Deirdre K. Tobias, Yanping Li.

Method: Correlated information on dietary intake of walnuts from two large epidemiological studies  with mortality.

Conclusions: We reported that higher consumption of walnut was associated with a lower risk of all-cause mortality and CVD mortality in two large prospective studies of U.S. elder adults, especially among those with suboptimal dietary quality. We estimated a greater life expectancy at age 60 of 1.3 years in women and 1.26 years in men, among those who consumed walnuts more than 5 servings/week compared to non-consumers.

Conflicts of interest: Li has received research support from California Walnut Commission. The funder has no role in the design and conduct of the study, in the collection, analysis, and interpretation of the data, and in the preparation, review, or in the decision to publish the results. All other authors have reported that they have no relationships relevant to the contents of this paper to disclose.

Comment: In addition to Haspel’s comments, I would add that the statement that the funder had no role is difficult to evaluate.  Industry funders generally do not pay for research likely to come out with results unfavorable to their products and much evidence suggests that influence is exerted at an unconscious level.  I provide evidence for this and other observations about industry “funding effects”—observations that research sponsored by food companies almost invariably produces results favorable to the sponsor’s interests but that recipients of industry funding typically do not recognize its influence—in my book, Unsavory Truth: How Food Companies Skew the Science of What We Eat.

I must also point out that walnuts are not the only nuts singled out for specific health benefits.  See, for example, “Pecan-Enriched Diets Alter Cholesterol Profiles and Triglycerides in Adults at Risk for Cardiovascular Disease in a Randomized, Controlled Trial” in a recent issue of the Journal of Nutrition.  Its sponsor was the Georgia Pecan Commission.

The bottom line: eat whatever nuts you like.

I know I’ve already posted one of these this week, but this one is too good not to share.

Let’s start with the press coverage: Snack yourself young: Study investigates the effects of daily almond consumption on wrinkles

A study by American research found that eating almonds daily reduces wrinkle severity – along with improving skin pigmentation – in postmenopausal women.

The 2021 study – published in Nutrients and funded by the Almond Board of California – expands upon findings of a 2019 study​​ that found there may be more than one reason to add almonds to a daily skin care routine.​​

And here’s the study in question: Prospective Randomized Controlled Trial on the Effects of Almonds on Facial Wrinkles and Pigmentation.  Authors: Sivamani RK, Rybak I, Carrington AE, Dhaliwal S, et al.  Nutrients. 2021; 13(3):785

This is not their first on this topic.  See: Prospective randomized controlled pilot study on the effects of almond consumption on skin lipids and wrinkles.  Author: Sivamani RK, Foolad N, Vaughn AR, Rybak I, et al   Phytother Res. 2019 Dec;33(12):3212-3217

Nor are these the first studies to link specific foods to wrinkle prevention.  I’ve written previously about a study on mangos and wrinkle prevention, sponsored—of course—by a mango trade association.

I wish companies and trade associations would stop doing studies of one food and some health outcome. Diets that contain reasonable proportions of fruits, vegetables, and whole grains are demonstrably healthy.  Can any one food really make all that much difference?

The sellers of these foods would like you to think they are “superfoods.”  Alas, no such thing exists.  But it’s a great marketing strategy.

As for sponsored research in general?

For a summary of research on the “funding effect”—the observation that research sponsored by food companies almost invariably produces results favorable to the sponsor’s interests but that recipients of industry funding typically do not recognize its influence—see my book, Unsavory Truth: How Food Companies Skew the Science of What We Eat.