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Plant-Heavy Diets May Harm Brain Health
Vegan and vegetarian diets need to include key brain nutrients

09/16/2019 By Craig Weatherby

People adopt “plant-based” diets for various reasons, but what does that term mean?

By “plant-based”, most researchers mean diets that — compared with the standard American diet — provide substantially more of their calories from plant foods.

As well as vegan and vegetarian diets, the term “plant-based” covers eating plans — such as the Mediterranean diet — that get most of their calories from vegetables, fruits, beans, nuts, and seeds.

Vegan and vegetarian diets are often called environmentally and nutritionally superior, but the evidence for both propositions is equivocal.

For example, recent population studies in the U.S. and Japan both linked plant-source protein to reduced death risks and animal protein — especially processed red meat — to higher risks (Song M et al. 2016; Budhathoki S et al. 2019).

However, the Japanese study found no link between those risks and the amount of animal protein people ate — probably because most animal protein in the Japanese diet comes from fish rather than red meat.

There's much better evidence for the environmental superiority of vegetarian and other plant-centric diets, versus diets featuring lots of beef and pork, such as the standard American diet (Sadly, the environmental claims made for "holistic planned grazing" in Allan Savory's famous TED talk don't seem to hold up under close scrutiny.)

However, debates about plant-rich versus meat-rich diets often fail to distinguish between types of animal protein, with pasture-raised poultry and wild fish being far more sustainable sources than beef or pork. 

And, importantly, modest consumption of grass-fed beef or bison — especially from cattle fed methane-curbing seaweed — appears much more sustainable.

Now, an editorial in the British Medical Journal (BMJ) adds to a chorus of experts who are raising alarms about the absence or scarcity of key brain nutrients in vegetarian and vegan diets.

Before we get to the concerns raised in that editorial, let’s look at a recent and widely publicized but highly controversial report recommending a plant-based diet.

Prominent commission’s Planetary Plate plan draws fire
The EAT-Lancet Commission on Food, Planet, Health included 37 of what the British medical journal Lancet called “world-leading” scientists.

They were charged with the task of devising a sustainable, healthy diet to feed the planet’s near-future population of 10 billion people.

Unsurprisingly, the EAT-Lancet commission’s report — issued earlier this year — recommended that we transform global eating habits, improve food production, and reduce food waste (Willett W et al. 2019).

Those are worthy goals, given the unhealthfully sugary, starchy, oily diets that have quickly spread across the globe, and the clearing (often by burning) of vast areas of carbon-capturing forest to produce soybeans, palm oil, and beef.

But, as well-informed critics have pointed out, EAT-Lancet Commission’s “Planetary Plate” diet plan — which calls for a dramatic shift from animal foods to plant-based foods — relies on outdated science.

Sadly, in part because it slashes animal protein to a small portion of daily calories, the EAT-Lancet Commission’s Planetary Plate plan calls for very little fish — an astonishing recommendation, given the mountain of evidence in favor of fish-rich diets.

The EAT-Lancet commission’s Planetary Plate diet plan — see the graphic depictions below and the original, larger graphics here — has been criticized by expert observers who question its scientific validity and express concerns about its health impacts.

Planetary Plate eating plan
(animal protein in small red slice) 

Animal & plant proteins by source
(animal proteins in red slice)

 

 

 

 

Some of the plan's expert critics place blame on the Lancet's choice to chair the commission, Walter Willett, M.D., a famed nutritional epidemiologist and long-time professor at the Harvard School of Public Health.

Dr. Willett — and some of his prominent protégés — are accused of promoting outdated advice, based on potentially biased research: see Big Sugar Paid Scientists to Pin Heart Disease on Saturated FatsOily Omega Myths Persist, and Experts Critique Saturated-Fat/Cardio-Harm Claims.

In fact, the World Health Organization (WHO) reversed its initial decision to endorse the EAT-Lancet commission’s Planetary Plate diet, due to concerns about its scientific validity.

Many experts echoed the critique offered by Gian Lorenzo Cornado — Italy’s representative to the WHO — who warned that a global shift toward the EAT-Lancet Planetary Plate diet could lead to serious problems:

  • Harm human health
  • Cost millions of jobs linked to animal husbandry
  • Promote the production of unhealthful processed foods
  • Destroy demonstrably healthful traditional diets at the core of many cultural heritages

Let’s return to the focus of this article: a widely publicized editorial in the British Medical Journal that raises concerns about plant-heavy diets with few-to-no animal foods.

Nutrition expert echoes concerns about plant-heavy diets
Recently, we reported on a university study from Finland that linked higher choline intakes to better brain performance and reduced dementia risks: see The “Secret” Brain-Saver in Meat and Seafood.

Nutrition scientist Emma Derbyshire, Ph.D., recently penned a widely publicized — and critiqued as exaggerated — editorial in the British Medical Journal's Nutrition, Prevention, & Health publication.

She is a former Senior Lecturer at Britain’s Manchester Metropolitan University, but has also served on the Meat Advisory Panel and received funding from the Agriculture and Horticulture Development Board, which represents the interests of beef, lamb, pork, and dairy producers.

Ms. Derbyshire fears that growing momentum toward plant-based and vegan diets risks worsening already low intakes of essential brain nutrients (Derbyshire E 2019).

It's important to note that there haven't been reports of brain harm among vegans and vegetarians due to choline deficiencies. However, the concern is long-term effects of deficiencies, which could be subtle but significant.

Her essay focuses on deficiencies of choline — an essential nutrient that is produced by the liver, but not in amounts big enough to meet the needs of our bodies and brains.

As Derbyshire noted in her editorial, choline — sometimes called vitamin B4 — is critical to brain health, particularly during fetal development, and affects liver function.

Unfortunately, like many people around the world, the average American doesn’t get enough choline. That shortage matters because — in addition to raising the risk of dementia — choline deficiencies are linked to unhealthful blood-fat metabolism and to free radical damage in our cells.

For more about choline, see The “Secret” Brain-Saver in Meat and Seafood, in which we reported on a Finnish university study that supports prior evidence linking higher choline intakes to better brain performance and reduced dementia risks.

The primary sources of dietary choline are beef, eggs, dairy products, fish, and chicken, with much smaller amounts found in nuts, and certain vegetables.

Beans rank as the richest plant sources of choline, and soybeans have the most, providing more choline than equal amounts of fish, poultry, or ground beef.

In 1998, the US Institute of Medicine recommended minimum daily choline intakes of 425 mg/day for women, 550 mg/day for men, and 450 to 550 mg/day for pregnant and breastfeeding women, respectively. Likewise, the European Food Safety Authority published similar guidelines in 2016.

As Derbyshire said about global shortages of dietary choline, “This is … concerning given that current trends appear to be towards meat reduction and plant-based diets.”

She fears that the reduced intakes of whole milk, eggs and animal protein — like those recommended in the EAT-Lancet Planetary Plate guidelines — hold negative implications for brain and metabolic health.

Her editorial stressed the need for greater awareness, and the need for choline supplements in plant-heavy diets: “More needs to be done to educate healthcare professionals and consumers ... if choline is not obtained in the levels needed from dietary sources per se then supplementation strategies will be required ...”.

A well-rounded vegan/vegetarian diet can provide sufficient amounts, and as Ms. Derbyshire said, supplemental choline is readily available as a brain-function "insurance policy".

Choline per 3.5-ounce (100g) serving

 

British nutritionist also expresses concern about low omega-3 intakes
Derbyshire also worries that heavily plant-reliant diets will further reduce most people’s already-low intakes of the omega-3 fats (DHA and EPA) critical to brain and immune functions, which abound only in fish and seafood.

Last year, her review of the evidence from 25 randomized, controlled clinical trials involving 3,633 people concluded that — compared with control groups — people assigned to take omega-3 supplements showed improvements in blood markers for cardiovascular and metabolic health (Derbyshire E 2018).

Perhaps unsurprisingly, her evidence review also found that omega-3 supplements deliver the greatest benefits to those with low omega-3 blood levels, breastfeeding women, and people diagnosed with depression.

As she wrote, “Bearing in mind the scale of aging populations and rising healthcare costs linked to poor brain health, omega supplementation could be a useful strategy for helping to augment dietary intakes and support brain health across the lifespan.”

As it happens, fatty fish are the only foods rich in both choline and omega-3 DHA and EPA, making them ideal foods for promoting optimal brain and metabolic health.

Sources

  • American Academy of Pediatrics. Food for Thought: AAP Aims to Ensure Kids Get Key Nutrients for Brain Development. January 22, 2018. Accessed at https://www.aap.org/en-us/about-the-aap/aap-press-room/Pages/Food-for-Thought-AAP-Aims-to-Ensure-Kids-Get-Key-Nutrients-for-Brain-Development.aspx
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  • Briske DD, Bestelmeyer BT, Brown JR, Fuhlendorf SD, Polley HW. 2013. The Savory Method can not green deserts or reverse climate change. A response to the Allan Savory TED video. Rangelands 35: 72–74
  • Budhathoki S, Sawada N, Iwasaki M, Yamaji T, Goto A, Kotemori A, Ishihara J, Takachi R, Charvat H, Mizoue T, Iso H, Tsugane S; Japan Public Health Center–based Prospective Study Group. Association of Animal and Plant Protein Intake With All-Cause and Cause-Specific Mortality. JAMA Intern Med. 2019 Aug 26. doi: 10.1001/jamainternmed.2019.2806. [Epub ahead of print]
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  • Derbyshire E. Could we be overlooking a potential choline crisis in the United Kingdom? BMJ Nutrition, Prevention, & Health. 2019;0:1–4. doi:10.1136/bmjnph-2019-000037
  • European Food Safety Authority. Dietary reference values for choline. EFSA Panel on Dietetic Products, Nutrition and Allergies (NDA) EFSA Journal 2016;14.
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