Research shows how a diet change might help US veterans with Gulf War illness

A new study from American University shows the results from a dietary intervention in U.S. veterans suffering from Gulf War Illness, a neurological disorder in veterans who served in the Persian Gulf War from 1990 to 1991.

The veterans’ overall number of symptoms were reduced and they experienced less pain and fatigue after one month on a diet low in glutamate, which is a flavor enhancer commonly added to foods, and that also functions as an important neurotransmitter in the nervous system.

Because the symptoms of GWI are similar to those of fibromyalgia, the U.S. Department of Defense provides funding for previously tested treatments in fibromyalgia that could also help veterans suffering from GWI. The low glutamate diet was previously shown to reduce symptoms in fibromyalgia, and thus, was a candidate for this funding. There are no cures for either illness, and treatments are being sought for both to manage chronic pain. GWI is thought to be connected to nervous system dysfunction in veterans. In the Gulf War, soldiers were exposed to various neurotoxins such as chemical warfare agents, pyridostigmine bromide (PB) pills, pesticides, burning oil fields, and depleted uranium.

“Gulf War Illness is a debilitating disorder which includes widespread pain, fatigue, headaches, cognitive dysfunction, and gastrointestinal symptoms. Veterans with GWI have a reduced quality of life as compared to veterans who do not have the illness,” said AU Associate Professor of Health Studies Kathleen Holton, who explores how food additives contribute to neurological symptoms and is a member of AU’s Center for Behavioral Neuroscience. “In this study testing the low glutamate diet, the majority of veterans reported feeling better. We saw significant reductions in their overall number of symptoms and significant improvements in pain and fatigue.”

The study, published in the journal Nutrients, details the experiments in a clinical trial of 40 veterans with GWI. The study participants were randomized to either immediately start the low glutamate diet for one month, or to a control group. After completion of the one-month diet, participants were challenged with monosodium glutamate and placebo to see if symptoms returned.

The challenge with MSG versus placebo resulted in significant variability in response among participants, with some subjects worsening, while others actually improved. This suggests that while a diet low in glutamate can effectively reduce overall symptoms, pain, and fatigue in GWI, more research is needed to understand how the diet may be altering how glutamate is handled in the body, and the specific role that nutrients may play in these improvements.

The role of glutamate

Glutamate is most easily identified when it is in the form of the food additive MSG; however, it appears most commonly in American diets hidden under many other food additive names in processed foods. Americans also consume glutamate through some foods where it occurs naturally, such as soy sauce, fish sauce, aged cheeses like parmesan, seaweed, and mushrooms.

Glutamate is known to play a role in pain transmission, where it functions as an excitatory neurotransmitter in the nervous system. When there’s too much of it, it can cause disrupted signaling or kill cells, in a process called excitotoxicity. Previous research has shown that glutamate is high in pain processing areas of the brain in individuals with fibromyalgia and migraine. High concentrations of glutamate have also been linked to epilepsy, multiple sclerosis, Parkinson’s disease, ALS, cognitive dysfunction (including Alzheimer’s), and psychiatric issues such as depression, anxiety and PTSD.

In her research, Holton limits people’s exposure to glutamate, while also increasing intake of nutrients known to protect against excitotoxicity. She analyzes how diet affects cognitive function, brain wave activity, brain glutamate levels, and brain function using MRI. In the study of veterans, the low glutamate diet was made up of whole foods low in additives and high in nutrients. Holton theorizes that the increased consumption of nutrients that are protective against excitotoxicity may have led to improved handling of glutamate in the nervous system. The study and diet tested in the veterans were similar to her previous studies, where she observed improvements in those with fibromyalgia, as well as in Kenyan villagers living with chronic pain.

It will take more research to determine if reducing exposure to glutamate can be used as a treatment for chronic widespread pain and other neurological symptoms in U.S. veterans with GWI. Holton is currently pursuing funding for her next grant, which will recruit 120 veterans for a Phase 3 clinical trial to confirm the study’s findings in a larger group, and further explore the mechanisms for these effects.

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Materials provided by American University. Original written by Rebecca Basu. Note: Content may be edited for style and length.


Japanese sake: the new pick-me-up? Yeast strain makes fatigue-fighting ornithine

Fans of sake, the traditional Japanese alcoholic beverage, may have even more reason to enjoy it now: Japanese scientists have discovered that a mutant strain of sake yeast produces high levels of the amino acid ornithine.

In a study published this month in Metabolic Engineering, researchers from the Nara Institute of Science and Technology and the Nara Prefecture Institute of Industrial Development have revealed that a mutant strain of sake yeast produces 10 times the amount of the amino acid ornithine compared with the parent yeast strain.

Ornithine is a non-protein-making amino acid and a precursor to two amino acids — arginine and proline. It has been found to perform several physiological functions, such as reducing fatigue and improving sleep quality.

“We wanted to obtain sake yeast strains with improved ethanol tolerance,” says a first author of this article, Masataka Ohashi. “During sake fermentation, the yeast is exposed to high concentrations of ethanol, which impedes yeast cell growth, viability and fermentation. Increased ethanol tolerance in sake yeast strains could improve ethanol production and reduce fermentation time.”

To find ethanol-tolerant yeast strains, the researchers isolated mutants that accumulated proline, which can alleviate ethanol toxicity, using a conventional mutagenesis (i.e., one that doesn’t involve genetic modification). They also conducted whole genome sequencing analysis, and performed brewing tests with sake yeast strains. Then they identified and analyzed a new mutation in a gene that encodes a variant of N-acetyl glutamate kinase that increases intracellular ornithine level.

“We previously constructed self-cloning industrial yeast strains that accumulate proline to increase ethanol tolerance and productivity of yeast,” explains Prof. Hiroshi Takagi, a corresponding author. “But those yeasts have not been yet acceptable to consumers because they’re considered to be genetically modified, even though a self-cloning yeast has no foreign genes or DNA sequences — they only have yeast DNA.”

The researchers successfully isolated non-genetically modified yeasts that produced 10 times the amount of ornithine compared with the parent strain, which is widely used in Japanese sake breweries, and the sake brewed with them contained 4-5 times more ornithine.

The results of this study will contribute to the development of improved yeast strains for production of high levels of ornithine, and the strain obtained in this study could be readily applied to sake, wine, and beer brewing. Ornithine-accumulating yeast strains could also be used in the production of ornithine-rich dietary supplements made from these yeasts and their products.

Prof. Takagi also describes “There are two major purposes for breeding of industrial yeast: improvement of fermentation ability with enhanced tolerance to environmental stresses during fermentation processes and diversity of product taste and flavor with modified metabolic pathways. In yeast, amino acid metabolisms vary under different growth environments and the metabolic styles form a complicated but robust network. The elucidation of metabolic regulatory mechanisms and physiological roles for amino acids is important fundamental research for understanding life phenomenon. The yeast is reliable and safe in food production, and thus the development of novel strains that overproduce ‘functional amino acids’ such as ornithine, proline and branched-amino acids, would greatly contribute to food-related industries.”

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School meals matter: federal policy can improve children’s nutrition and health (Jia et al. 2020)


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New type of taste cell discovered in taste buds

Our mouths may be home to a newly discovered set of multi-tasking taste cells that — unlike most known taste cells, which detect individual tastes — are capable of detecting sour, sweet, bitter and umami stimuli. A research team led by Kathryn Medler at the University at Buffalo reports this discovery in a study published 13th August in PLOS Genetics.

Taste buds in the mouth are critical to our survival and help us to decide whether a food is a good source of nutrients or a potential poison. Taste buds employ three types of taste cells: Type I cells acts as support cells; Type II cells detect bitter, sweet and umami tastes; and Type III cells detect sour and salty flavors. To better understand how taste cells detect and signal the presence of different tastes, the researchers used an engineered mouse model to investigate the signaling pathways that the animals use to relay taste information to the brain. They discovered a previously unknown subset of Type III cells that were “broadly responsive” and could announce sour stimuli using one signaling pathway, and sweet, bitter and umami stimuli using another.

The idea that mammals might possess broadly responsive taste cells has been put forth by multiple lab groups, but previously, no one had isolated and identified these cells. The researchers suspect that broadly responsive cells make a significant contribution to our ability to taste. Their discovery provides new insight into how taste information is sent to the brain for processing, and suggests that taste buds are far more complex than we currently appreciate.

“Taste cells can be either selective or generally responsive to stimuli which is similar to the cells in the brain that process taste information,” commented author Kathryn Medler. “Future experiments will be focused on understanding how broadly responsive taste cells contribute to taste coding.”

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Adding a meter between meals boosts vegetarian appeal

Meat-heavy diets not only risk our health but that of the planet, as livestock farming on a massive scale destroys habitats and generates greenhouse gases.

Conservationists at the University of Cambridge are investigating ways of “nudging” people towards eating more plants and less meat, to help curb the environmental damage caused by excessive consumption of animal products.

The researchers experimented on customers in the cafeterias of two Cambridge colleges to find out whether the position of vegetarian options influences the uptake of plant-based dining.

They collected and analysed data from 105,143 meal selections over a two-year period, alternating the placement of meat and veg dishes every week, and then changing the pattern to every month.

The size of the study is unprecedented. A previous review of various studies using “choice architecture” to reduce meat intake only reached a combined total of 11,290 observations.

The researchers found that simply placing veggie before meat in the order of meal options as people entered the serving area did little to boost green eating in one of the colleges.

In the other college, however, the sales of plant-based dishes shot up by a quarter (25.2%) in the weekly analysis, and by almost 40% (39.6) in the monthly comparison.

The difference: almost a metre of added distance between the vegetarian and meat options, with an 85cm gap in the first college compared to a 181cm gap in the second. The findings are published today in the journal Nature Food.

“Reducing meat and dairy consumption is one of the simplest and most impactful choices we can make to protect the climate, environment and other species,” said study lead author Emma Garnett, a conservationist from Cambridge’s Department of Zoology.

“We’ve got to make better choices easier for people. We hope to see these findings used by catering managers and indeed anyone interested in cafeteria and menu design that promotes more climate friendly diets.”

The latest research follows on from work by Garnett and colleagues published last autumn, which showed that adding an extra veggie option in cafeterias cuts meat consumption without denting overall sales.

Livestock and aquacultures behind meat, fish, dairy and eggs are responsible for some 58% of the greenhouse gas created by global food, and take up 83% of farmland despite contributing to just 18% of the world’s calorie intake.

Recently, Cambridge researchers recommended eating less meat to reduce the risk of future pandemics, and the UK’s public sector caterers pledged to cut the amount of meat used in schools and hospitals by 20%.

The experiments were conducted across two colleges — one with 600 students and one with 900 students — where cafeteria customers were presented with vegetarian and meat options in differing orders for weekday lunch and dinner.

College members take a tray, view the meals on offer, and then ask serving staff to dish up their preferred options. Food is purchased by swiping a university card, and the researchers gathered anonymised data on main meal selections only (sandwiches and salads went uncounted).

While the catering managers helped to set the experiments up, the diners remained unaware.

The researchers had expected to see a difference in vegetarian sales through order alone, but it was only in the college with the extra metre — the 181cm gap — between food options that recorded an uptick when arranged “Veg First.”

To confirm the findings, researchers reduced the gap in this cafeteria to just 67cm, and vegetarian sales fell sharply. In fact, with such a small gap, vegetarian dishes fared even worse when put first in line (falling almost 30% compared to “Meat First” days).

“We think the effect of the metre may be down to the additional effort required to seek out meat. If the first bite is with the eye, then many people seem perfectly happy with an appetising veggie option when meat is harder to spot,” said Garnett.

“All cafeterias and restaurants have a design that ‘nudges’ people towards something. So it is sensible to use designs that make the healthiest and most sustainable food options the easiest to pick without thinking about it,” she said.

“We know that information alone is generally not enough to get us to change damaging habits. More research is needed on how to set up our society so that the self-interested default decision is the best one for the climate.”

Garnett’s research has contributed to food policy at the University of Cambridge, where the catering service has worked to reduce the amount of meat it uses.

Last year, University cafeterias (separate from the colleges) announced a 33% reduction in carbon emissions per kilogram of food purchased, and a 28% reduction in land use per kilogram of food purchased.