by Marion Nestle

Search results: superfood

Mar 1 2024

Weekend reading: the ironies of drinking fluid milk

Anne Mendelson.  Spoiled: The Myth of Milk as Superfood.  Columbia University Press, 2023 (396 pages).

 

I am an admirer of Anne Mendelson’s books and did a blurb for her Chow Chop SueyBut this one is over the top—original, compelling, brilliantly written.

Driving this book is a question I’ve not heard asked before, at least not so directly: Why and how did the consumption of fresh liquid milk (“drinking-milk”)—as opposed to fermented dairy products—become framed as a nutritional necessity?

Her question derives from some basic facts about cow’s milk and its industrial production:

  • Once cow’s milk leaves the udder, it is easily contaminated with pathogenic bacteria.
  • Most adults have stopped making the enzyme that digests the sugar lactose in milk and can’t drink it without getting unpleasant digestive systems.
  • To produce milk safely requires complicated and expensive industrial processes.
  • The cost of milk production exceeds the price people are willing to pay for it; dairy farming is a losing proposition even with taxpayer subsidies.
  • Industrial milk production is hard on cows and pollutes the environment.

Why are we even doing this?  For this, she blames 19th and 20th century European and American doctors who thought the ability to digest lactose normal, nutritionists (calcium!), and the USDA (3 servings a day!).

She is not against eating dairy foods when they are fermented.  These, yogurt and the like, are much safer.  Friendly bacteria split the lactose along with producing acid that destroys pathogens.

You don’t have to agree with all her points to appreciate how well they are argued.

To wit:

[The book] argues that influential nutritional theories about fresh and fermented milk took a disastrously wrong turn in the eighteenth century.  The reason is that the founders of modern Western medicine had no way of understanding the genetic fluke that allowed them, unlike most of the world’s peoples, to digest lactose from babyhood to old age.  In other words, today’s mega-industry stemmed from a lack of scientific perspective.  That lack turned the one form of milk that is most fragile, perishable, difficult to produce on a commercial scale, and economically pitfall-strewn into a supposed daily necessity for children and, to a lesser extent, adults.  [pp x, xi].

No other food product is as staggeringly difficult and expensive to get from source (in this case, a cow) to destination (milk glass on table) in something loosely approximating its first condition.  If one existed, it would be treated as an astounding luxury. [p. 1].

Mendelson takes deep dives into the history of dairy use, dietary recommendations, industrial production, and government dairy policy.  In attempting to teach about the Farm Bill, I was defeated by Milk Marketing Orders, the formulas used by the government to set price support levels required to be paid by “handlers” (milk processors) to dairy producers in different areas of the country.  I could not find anything about this in the index, alas, but I loved what she says about them on page 205.

These formulas gradually became as abstruse, and as unintelligible to anyone outside a small charmed circle, as anything in the bad old days before the federal government stepped in.  Far from abolishing the buyer’s market, they trapped farmers selling fluid milk within the marketing order system in endless struggles to wring enough out of handlers to recoup production costs….What I do understand is that as the postwar era advanced, the sheer incomprehensibility of producer-handler milk price schemes again became an endless frustration to dairy farmers, above all those trying to make a living within the marketing order system for drinking-milk.

One final irony:

Nothing is going to dislodge supermarket drinking-milk from its towering economic importance.  It is certain to continue along the track of expansion, consolidation, and increasingly complex technological infrastructure that it has pursued for almost three quarters of a century.  Big Milk is going to become Bigger Milk.  Its absurdities are also sure to become more entrenched.  The greatest of these is the plain fact that Americans are drinking less milk while dairy farms are producing more of it.

A personal comment: The book triggered a memory.  I once visited a school lunch program in Barrow (now Utqiaġvik), Alaska.  Inuit children were served the standard USDA lunch, which requires half-pint cartons of milk.  I did not see any of them drinking it.  The untouched cartons were discarded.  The milk was not only culturally inappropriate, but wasteful.  All food in that part of North Alaska has to be flown in on airplanes.

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Feb 12 2024

Industry-funded study of the week: Et tu saffron?

I learned about this one from NutraIngredients-Europe:

The ‘promising’ role of saffron in stress resilience:  New research conducted in partnership with botanical product manufacturer Pharmactive reveals that its standardized saffron extract Affron was able to normalise HPA [hypothalamic-pituitary-adrenal] axis dysregulation following chronic mild stress stimulation in a rat model…. Read more

I thought this was worth a closer look and went right to the paper.

Effects of Saffron Extract (Affron®) with 100 mg/kg and 200 mg/kg on Hypothalamic–Pituitary–Adrenal Axis and Stress Resilience in Chronic Mild Stress-Induced Depression in Wistar Rats. Nutrients 202315(23), 4855; https://doi.org/10.3390/nu15234855

Conclusion: These findings elucidate AFN’s [Affron®] role in stress mitigation, affirm its health benefits, validate its potential as a treatment for stress-related symptoms, confirm its physiological effectiveness, and emphasize its therapeutic promise.

Guess who generated and conducted this study.

Conflict of interest statement: For commercial affiliations, J.K. and S.Y. were employed by the company iCONNECTOME Co., Ltd., which had the roles of curation, formal analysis, and visualization in this study; S.-S.Y. was employed by the company iCONNECTOME Co.,Ltd., which had the roles of conceptualization, funding acquisition, investigation, supervision, review and editing in this study; M.-Y.K. and J.S. were employed by the company Hyundai Bioland Co.,Ltd., which had the roles of methodology and/or writing original draft in this study; M.I.M.-V. was employed by the company Pharmactive Biotech S.L.U., which had the role of investigation in this study. The remaining 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.

In case you wondered, Pharmactive Biotech makes Affron.  The other enterprises do the studies.

Who paid for this?

Funding: This research was funded by Hyundai Bioland Co., Ltd., grant number IC22_02, and Soonchunhyang University Research Fund. Hyundai Bioland Co., Ltd. had the following involvement with the study: participating in the research Investigation, and paid all costs for editing and publishing the Paper. The funder was not involved in the study design, collection, analysis, interpretation of data, the writing of this article or the decision to submit it for publication.

Comment: Huh?  I often suspect that the statement “the funder was not involved….” may not accurately represent the funder’s involvement (to put the matter politely).  In this case,  the role of Hyundai Bioland is self-contradictory.  Its employee-authors say they determined the study’s methods and/or wrote the paper, and the funder says it participated in the research but had no involvement in the study design, etc.  This is confusing, if not contradictory.

I do have to say something about marketing saffron as a superfood.  Saffron consists of the stigmas of crocus flowers, and these are hugely expensive.  Walmart is selling 2 grams for $42.

The Wikipedia entry iexplains why.

The high retail value of saffron is maintained on world markets because of labour-intensive harvesting methods, which require some 440,000 hand-picked saffron stigmas per kilogram…150,000 crocus flowers per kilogram…Forty hours of labour are needed to pick 150,000 flowers…One freshly picked crocus flower yields on average 30 mg of fresh saffron or 7 mg dried; roughly 150 flowers yield 1 g (132 oz) of dry saffron threads.

Once again, we have here an industry-funded marketing study pretending to be science.  But really, saffron?   OK, an extract that maybe can be synthesized, but still.  There have to be easier and less expensive ways to reduce stress and depression in rats.

Oh.  And in case you were wondering how scientists determine whether rats are depressed?

Our previous animal behavioral assays assessing anxiety and depression, including the elevated plus maze, forced swim, and sucrose preference tests, have revealed that AFN-treated animals (200 mg/kg) exhibit behaviors indicative of anhedonia and depression mitigation [27]. For example, increased consumption of sugar solutions and improved specific escape responses have been observed in forced swim tests.

Ref 27 is: Orio, L.; Alen, F.; Ballesta, A.; Martin, R.; Gomez de Heras, R. Antianhedonic and Antidepressant Effects of Affron®, a Standardized Saffron (Crocus sativus L.) Extract. Molecules 202025, 3207. [Google Scholar]

Oct 16 2023

Industry funded studies of the week: Nuts and more nuts

I have so many of these waiting to be posted that I might as well do a bunch of them all at once.

Almonds

The study: Prospective Randomized Controlled Trial on the Effects of Almonds on Facial Wrinkles and Pigmentation. Nutrients 2021, 13(3), 785; https://doi.org/10.3390/nu13030785.

Conclusion: “the daily consumption of almonds may contribute to the improvement of facial wrinkles and reduction of skin pigmentation among postmenopausal women with Fitzpatrick skin types I and II.”

Funder: Almond Board of California

Comment: Thanks to Lori Rothman for sending this one.  It’s not the first time I’ve posted an almonds-and-wrinkles study; here’s the other from 2021.   And please note.  It’s not just almonds.  Mangos do this too.  But the Almond Board is working hard on turning almonds into superfoods. Members of the Academy of Nutrition and Dietetics were sent an announcement “Exciting new research investigates the link between almonds and these three key areas: Exercise recovery, prediabetes and skin health. That ad sends you to “Dietitian Tools” on the California Almonds website, where you can find a handy link to the study.

Here’s another one:

The study: Almond intake alters the acute plasma dihydroxy-octadecenoic acid (DiHOME) response to eccentric exercise.Front. Nutr., 09 January 2023  Volume 9 – 2022 | https://doi.org/10.3389/fnut.2022.1042719

Conclusions: “In general, 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. Other almond-related benefits for exercisers revealed in this study include reduced feelings of fatigue and tension, better leg-back strength during recovery, and decreased muscle damage during the first day of recovery.”

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.

Comment: That’s what they all say.

Macadamias

The study: Macadamia nut effects on cardiometabolic risk factors: a randomised trial  J Nutr Sci. 2023.

Conclusion: “Daily consumption of macadamia nuts does not lead [sic]to gains in weight or body fat under free-living conditions in overweight or obese adults; non-significant cholesterol lowering occurred without altering saturated fat intake of similar magnitude to cholesterol lowering seen with other nuts.”

Funding: This study was funded by Hort Innovation, Sydney, Australia (Project code MC17005).  J. J., K. O. and F. M. – None; J. S., S. R. and C. H. have received research funding through their institution from Hort Innovation, Sydney, Australia.  Note: “Hort Innovation is a grower-owned, not-for-profit research and development corporation with the goal of creating value for horticulture growers and those across the horticulture supply chain. It invests more than $120 million in R&D, marketing and trade programs on behalf of industry.”

Peanuts

The study:  Urinary Phenolic Metabolites Associated with Peanut Consumption May Have a Beneficial Impact on Vascular Health Biomarkers. Antioxidants. 2023; 12(3):698. https://doi.org/10.3390/antiox12030698.

Conclusion:  “the present study shows for the first time that regular peanut and peanut butter consumption could have a positive impact on vascular biomarkers in healthy young adults.”

Funding: This research was supported by funding from the Peanut Institute.

Tree Nuts

The study: Tree Nut and Peanut Consumption and Risk of Cardiovascular Disease: A Systematic Review and Meta-Analysis of Randomized Controlled Trials. Advances in Nutrition.  May 04, 2023  https://doi.org/10.1016/j.advnut.2023.05.004

Conclusion: “The findings of this review provide evidence of a combined effect of tree nuts and peanuts on a range of biomarkers to create an overall CVD risk reduction.”

Funding: “The findings of this review provide evidence of a combined effect of tree nuts and peanuts on a range of biomarkers to create an overall CVD risk reduction.”

Author disclosures: Two of the authors received previous funding from the International Nut and Dried Fruit Council or the California Walnut Commission.

Comment: If you are interested in doing nut research, trade associations will be happy to fund it.  But maybe only if the results come out the way the funder wants them to?

And another one on tree nuts.

The study: Mixed Tree Nuts, Cognition, and Gut Microbiota: A 4-Week, Placebo-Controlled, Randomized Crossover Trial in Healthy Nonelderly Adults.  J. Nutrition.   VOLUME 152, ISSUE 12, P2778-2788, DECEMBER 2022.  https://doi.org/10.1093/jn/nxac228

Conclusions: “These findings indicate a positive effect of nut on cognition following only 4 wk of consumption in a healthy nonelderly sample, as well as upregulation of a microbial taxa associated with gut health.

Funding: This study was supported by funding from the INC (International Nut and Dried Fruit Council).

Walnuts

The California Walnut Commission and the USDA have put out a request for research proposals on the effects of walnuts on sleep and mental health (I learned about this one from a Tweet (oops, X).  Want to do it?  You can get up to $300,000.

Comment: I guess I don’t have much imagination but I cannot think of a reason why walnuts in particular would have anything to do with sleep or mental health.  But I’ll bet enterprising investigators can figure something out.  Stay tuned on this one.

Overall comment

My point about all of these studies is that you can usually predict who paid for them by their titles and if you know who paid for them, you can pretty well predict what they will find.  Nut trade associations want you to eat more nuts, preferably the kind they represent.  Nuts are just fine for health, but watch the calories.  And do not expect miracles—ever—from eating just one healthy food.

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Nov 17 2022

Hyping research: coffee

I always appreciate the Headline vs. Study sections of the Obesity and Energetics newsletter that arrives in my email once a week.

This one concerns coffee.  It amuses me that researchers are always trying to prove either that coffee is a superfood or that it is poison.

It’s neither, but never mind.  The research is fun to track.

Headline: Coffee Lowers Risk of Heart Problems and Early Death, Study Says, Especially Ground and Caffeinated.

Researchers found “significant reductions” in the risk for coronary heart disease, congestive heart failure and stroke for all three types of coffee. However, only ground and instant coffee with caffeine reduced the risk for an irregular heartbeat called arrhythmia. Decaffeinated coffee did not lower that risk, according to the study published Wednesday in the European Journal of Preventive Cardiology.

Press-Release: Coffee Drinking Is Associated with Increased Longevity.

Study: Self-Reported Coffee Consumption in the UK Biobank… Again. Causation Not Established.

Drinking two to three cups of coffee a day is linked with a longer lifespan and lower risk of cardiovascular disease compared with avoiding coffee, according to research published today in the European Journal of Preventive Cardiology, a journal of the ESC.1 The findings applied to ground, instant and decaffeinated varieties.

Headline vs Study Déjà Vu: For More Coffee in the UK Biobank Headlines, See Headline vs Study from July 30, 2021.

And just for fun, here’s the Washington Post’s adorable interactive comparison of the relative benefits of coffee vs. tea.

My view?  Drink whichever you like, don’t worry, be happy, enjoy!

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Jul 26 2022

Tara flour: a quick review of the research

A review article finds it nontoxic.You may recall that on June 17,  Daily Harvest issued a recall of its frozen vegan Crumbles product  after 500 or so adverse event reports, many of  severe liver damage among the 28,000 customers who ordered it.

Here’s what the front of the package looked like.

This product has lots of ingredients:

organic butternut squash, organic hemp seeds, organic cauliflower rice, organic extra virgin olive oil, organic french lentils, organic red lentils, organic tri-colored quinoa, organic cremini mushrooms, organic tara flour, organic leeks, organic parsley, water, organic cassava root flour, organic flax seeds, organic sacha inchi powder, chia seeds, organic porcini powder, himalayan sea salt, organic apple cider vinegar, organic onion powder, nutritional yeast, organic garlic powder, organic tomato powder, organic white pepper, organic coriander seeds, organic mustard powder, organic thyme.

As food safety lawyer Bill Marler predicted, tara flour has been identified as the ingredient at fault.

I had never heard of tara and had to look it up.  Since then, I’ve gotten curious and did some quick research.

Tara is a legume—a bean plant—grown in Peru and other Latin American countries.

Tara is grown for several purposes:

  • Pod tannins for industrial leather, keeping ships free of marine animals, and preparing textiles to accept dyes
  • Cosmetics (polysaccharides isolated from the seeds)
  • Food additives—protein flours and gums (from the endosperm)

The research literature on tara is remarkably extensive (Who knew?).

On the tannins:

On cosmetics:

On tara as a food ingredient:

From everything previously reported about tara over the past 20 years, there is no reason to think it might be unsafe.

So what’s going on?  How to explain “only” hundreds of cases of severe liver injury when 28,000 Crumbles meals were shipped during the time when cases were reported.

Possibilities:

To prevent this from happening again, it’s necessary to identify the toxin.  I hope that happens soon.

Jul 11 2022

Industry-funded studies: avocados yet again

It’s been more than a year since I last wrote about avocado industry funding of research but the Avocado Nutrition Center has been sending out press releases so it’s time for another look.

Given the Superbowl—105 million pounds of avocados consumed that day by one estimate—you might not think that the avocado industry would have to work as hard as it does to convince you that avocados are a superfood.

But maybe what it is trying to do is to get us to ignore the effects of our demand for avocados on deforestation and social unrest in Mexico.

The avocado industry is a good example of how to fund research for marketing purposes.  It funds the Avocado Nutrition Center’s research program.

The program’s website covers dozens of industry-funded studies that demonstrate benefits of avocados for cardiovascular health, weight management, type 2 diabetes, and healthy living at every age.

Here’s how the Center uses them.

Another recent study of 2,886 older adults, published in Frontiers in Nutrition, examined cognitive function among older American avocado consumers compared to nonconsumers.

On that basis, the Center produced a fact sheet: Proactive thinking on cognition.  

The Center also lists a few independently funded studies that produced equally beneficial results.

I picked one at random and looked it up: Avocado Consumption and Risk of Cardiovascular Disease in US Adults.

  • Conclusion: Higher avocado intake was associated with lower risk of CVD and coronary heart disease in 2 large prospective cohorts of US men and women. The replacement of certain fat-containing foods with avocado could lead to lower risk of CVD.
  • Funding: mostly by NIH
  • Conflicts of interest: the lead author reports having “collaborated in the Hass Avocado Board–funded trial Effects of Avocado Intake on the Nutritional Status of Families during 2016 to 2019 as a graduate student researcher, but the present study was not supported or endorsed by the Hass Avocado Board. The remaining authors have no disclosures to report.”

And here’s the most recent study: Effect of Incorporating 1 Avocado Per Day Versus Habitual Diet on Visceral Adiposity: A Randomized Trial

  • Conclusion: Addition of 1 avocado per day to the habitual diet for 6 months in free‐living individuals with elevated waist circumference did not reduce visceral adipose tissue volume and had minimal effect on risk factors associated with cardiometabolic disorders.
  • Funding: This work was supported by the Avocado Nutrition Center.

Why be concerned?  Aren’t avocados good for you?

Sure, and I love them.  But superfoods?  All fruits and vegetables have useful nutrients, but some have fewer calories (a serving size is one-third of an avocado) and most are less caught up in ecological damage.

I discuss the scientific reasons for concern in my book, Unsavory Truth: How Food Companies Skew the Science of What We Eat.  In it, I review the literature on the “funding effect”—the observation that research sponsored by food companies almost invariably produces results favorable to the sponsor’s interests.  Research on conflicts of interest also demonstrates that recipients of industry funding do not recognize its influence, did not intend to be influenced, and deny the influence, despite vast amounts of research to the contrary.

Jul 5 2022

What’s up with the Daily Harvest recall?

Daily Harvest is a company that makes vegan meals, mostly organic, and freezes them for home delivery.

By mid-June, it had received 470 complaints from customers who ate a new product, French Lentil + Leek Crumbles, but developed severe liver and gall bladder problems.  On June 23,  Daily Harvest issued a recall of the product “due to potential health risk” (also see After 470 reports of illnesses, Daily Harvest recalls French Lentil + Leek Crumbles).

I was especially interested in this event for two reasons: Daily Harvest twice sent me meals to sample (before it introduced this one) and I knew they had to be cooked before eating, which would kill harmful microbes, and I could not imagine what could possibly cause reactions this toxic (as I explained to the New York Times).

This product’s ingredient list seems benign:

organic butternut squash, organic hemp seeds, organic cauliflower rice, organic extra virgin olive oil, organic french lentils, organic red lentils, organic tri-colored quinoa, organic cremini mushrooms, organic tara flour, organic leeks, organic parsley, water, organic cassava root flour, organic flax seeds, organic sacha inchi powder, chia seeds, organic porcini powder, himalayan sea salt, organic apple cider vinegar, organic onion powder, nutritional yeast, organic garlic powder, organic tomato powder, organic white pepper, organic coriander seeds, organic mustard powder, organic thyme.

More than that, on June 25, food safety lawyer Bill Marler was asking the same question: What is it in Daily Harvest’s French Lentil and Leek Crumbles that is causing liver failure?  He was sending samples out to his own labs.

On June 28, Daily Harvest responds to customers sickened, hospitalized from 1 of its products.

On June 30, the FDA published its Investigation of Adverse Event Reports: French Lentil & Leek Crumbles

On June 17, 2022, in response to consumer complaints submitted to the company, Daily Harvest voluntarily initiated a recall of their French Lentil & Leek Crumbles…From April 28 to June 17, 2022, approximately 28,000 units of the recalled product were distributed to consumers in the continental United States through online sales and direct delivery, as well as through retail sales at the Daily Harvest store in Chicago, IL, and a “pop-up” store in Los Angeles, CA. Samples were also provided to a small number of consumers. Daily Harvest emailed consumers who were shipped the affected product, and other consumers for whom the company had contact information and consumers were issued a credit for the recalled product. Consumers who may still have the recalled product in their freezers should immediately dispose of it.

On July 1, the FDA announced the recall and issued an advisory for these events.

Also on July 1,  Daily Harvest issued UPDATES ON OUR VOLUNTARY RECALL OF FRENCH LENTIL + LEEK CRUMBLES

Rachel here – I want to give you another update on the French Lentil + Leek Crumbles recall. As you know, we’ve been conducting exhaustive testing over the course of the last two weeks. Despite this, we still have not identified a possible cause. I am sorry that it’s taking as long as it is to pinpoint exactly what may have made people sick. We are deeply committed to finding answers for those impacted. We’re working with top doctors, microbiologists, toxicologists as well as 3 independent labs.   While additional testing is underway, results to date rule out the following:

  • Hepatitis A

  • Norovirus

  • A range of mycotoxins, including aflatoxins

  • Food-borne pathogens including Listeria, E.Coli, Salmonella, Staphylococcus Aureus (Staph), B.Cereus, and Clostridium Species

  • Major allergens including egg, soy, milk, and gluten

I assure you, we will not stop until we get to the bottom of this. We’re continuing to work in close cooperation with the FDA, CDC and other health agencies. The FDA released an update on their investigation yesterday, which can be found here on their website.

I’m baffled.  I can’t understand why toxin testing hasn’t come up with anything.  The illnesses are real and all traced to this product.

The FDA’s recommendation: “Consumers should not eat, sell, or serve recalled products. Consumers who may still have the recalled product in their freezers should throw it away.”

Bill Marler agrees with don’t eat it, but he wants the product saved as evidence.  He has questions and suggestions:

His hypothesis: the Tara ingredient.

We believe that the illnesses may well be linked to a common ingredient called Tara that comes exclusively from Peru (this due because it is a unique ingredient to the French Lentil + Leek Crumbles AND to certain Revive Smoothies where people are reporting identical symptoms).

Here’s what Wikipedia says about Tara:

Tara gum…is produced by separating and grinding the endosperm of T. spinosa seeds…The major component of the gum is a galactomannan polymer similar to the main components of guar and locust bean gums that are used widely in the food industry….Tara gum has been deemed safe for human consumption as a food additive… Medicinal uses in Peru include gargling infusions of the pods for inflamed tonsils or washing wounds; it is also used for fevers, colds, and stomach aches. Water from boiled, dried pods is also used to kill fleas and other insects.

Bill Marler is on the case.  He has 175 clients so far.

I’ve heard privately from people who experienced sickness after eating this product.  I’ve read about others like this one:

I wish everyone a speedy recovery, and hope the toxin gets identified soon.  Stay tuned.

May 2 2022

Industry-influenced study of the week: diet and brain atrophy

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.