Showing posts with label Walnut. Show all posts
Showing posts with label Walnut. Show all posts

Friday 8 December 2023

Walnuts for Brain Health in Aging and ADHD, but in Autism?


Source: Ivar Leidus - Own work, CC BY-SA 4.0,


Diet does seem to be the most popular intervention for autism and it does appear to give benefits, particularly in those with milder autism.

There are lessons to be learnt from healthy aging, when looking at how to optimise brain function in those with a neurodevelopmental disorder like autism.

As we age, multiple processes in the body start to function sub-optimally and this pretty much determines our healthy life expectancy. There are overlaps between features of this sub-optimal function (oxidative stress, mitochondrial dysfunction, neuroinflammation etc) and what is present in people with level 3 autism and/or intellectual disability.

The dietary keys to healthy aging:

A healthy varied diet rich in fruits, berries, vegetables, whole grains, legumes and nuts.

Healthy fats and lean protein.

To this we have to add all those herbs and spices.

Herbs, in large quantities, are a key element of the Mediterranean diet and are often omitted by people trying to copy this diet. I still remember meeting our reader Petra in Greece and receiving her gift of olive oil and oregano – it was a huge bag of oregano, not the size you might find in a supermarket in Northern Europe.

The healthy Okinawa diet is distinguished by low-calorie intake, fish, very little meat, fermented food (like natto), not to forget the seaweed. They also consume large amounts of a purple sweet potato. Okinawan sweet potatoes, also known as purple sweet potatoes, are a type of sweet potato that is native to Okinawa. They are characterized by their deep purple flesh, which is due to the presence of anthocyanins, a type of antioxidant.

I have to say that having visited an island in the Okinawa archipelago they also have some very unhealthy food adopted from US military bases. Spam sushi was everywhere, as are US style fast food outlets, with over-sized burgers. I found it hard going eating fish three times a day, albeit those small amounts.


Greece is no different, there are older Greeks with healthy traditional diets, but no shortage of giros and souvlaki joints catering to the locals and the tourists alike.



Nuts!  Not just at Christmas

Nuts are on the list of healthy foods, but I think most people neglect them.

It is difficult to incorporate sufficient nuts into your diet unless you are going to spend time eating them by the handful.

Incorporating large amounts of herbs like oregano, basil, sage, rosemary, thyme, parsley, mint etc is not so hard and you end up with much tastier food. They provide numerous health benefits. 

I was very surprised to find that there was so much evidence to support the humble walnut.

I was also surprised where some of the evidence comes from.

I did exchange emails many years ago with Abha Chauhan, a well-known researcher at the Institute for Basic Research in Developmental Disabilities in New York. She has written some very cutting edge research about oxidative stress.

She turns out to be a fan of walnuts.

She does actually list nutrition among her research interests:-

Alzheimer's disease, amyloid, free radicals, glutathione, mitochondria, nutrition, oxidative stress, protein kinases

 Her paper is here:-

Beneficial Effects of Walnuts on Cognition and Brain Health

I did previously wonder why New York has a research center into intellectual disabilities. Here is some information.


The Institute for Basic Research in Developmental Disabilities (IBR) is a proud part of New York State’s long history of caring for its citizens with developmental disabilities. It was in the 1940s and 1950s that the idea of creating an institute dedicated to studies in mental retardation was first discussed. In 1958, enabling legislation was passed for the creation of the Institute for Research in Mental Retardation within the New York State Department of Mental Hygiene. Ground was broken for the Institute’s research tower in 1964, and when its first laboratories opened in 1968, IBR was the first large-scale institute in the world with the mandate to conduct basic and clinical research into the causes of mental retardation. IBR became part of OPWDD, then known as the New York State Office of Mental Retardation and Developmental Disabilities (OMRDD) in 1979; a year later, it was renamed the Institute for Basic Research in Developmental Disabilities to reflect OMRDD’s broader focus on many developmental disabilities.  

Research is always good, but what really matters is translating it to therapy. How about actually getting kids with autism treated for oxidative stress? This I recall discussing with Abha and her response was that the funding is lacking for clinical trials. My response was that she could always give Mike Bloomberg a call.  How much money do you really need? 

Abha, Alzheimer’s and the walnut

As we saw Alzheimer’s was number one on Abha’s research interests. Here we have her paper suggesting walnuts for Alzheimer’s.


Benefits of a diet with walnuts in Alzheimer’s disease

Alzheimer’s disease is a severe neurodegenerative disorder, responsible for 60-70% of cases of dementia. The most common symptoms are memory loss, disorientation and loss of cognition. To date, there is no known cure for this disease, but Dr Abha Chauhan, based at the New York State Institute for Basic Research in Developmental Disabilities, New York, USA, has shown how supplementation with walnuts in the diet can help Alzheimer’s mice slow down the development of the disease. Her research demonstrates that walnuts can limit the oxidative stress characteristic of this condition, as well as promote the body’s natural antioxidant defence mechanisms. 

Based on these results, it’s reasonable to suggest that supplementation with walnuts may help in reducing the risk of developing Alzheimer’s disease, delaying its onset and/or slowing its progression due to the antioxidant and anti-inflammatory effects of different components of walnuts. At the very least, these results indicate that it may be worth conducting similar studies in humans.


It’s difficult to say at this stage what exactly in the walnut is responsible for these benefits, but in addition to antioxidants in walnuts, ALA (omega-3 fatty acid) may also be a contributing factor. While most nuts contain monounsaturated fats, only walnuts consist primarily of polyunsaturated fat, of which ALA is the main constituent. This fatty acid is the precursor of vital fatty acids, important for regulating serotonin and dopamine concentrations, as well as modulating key inflammatory and immune functions.


Beneficial Effects of Walnuts on Cognition and Brain Health

Oxidative stress and neuroinflammation have important roles in the aging process, mild cognitive impairment (MCI), Alzheimer’s disease (AD), and other brain disorders. Amyloid beta protein (Aβ) is the main component of amyloid plaques in the brains of people with AD. Several studies suggest that Aβ increases the generation of free radicals in neurons, which leads to oxidative damage and cell death. Aβ can also induce neuroinflammation by increasing pro-inflammatory cytokines and enzymes. Walnuts contain several components that have antioxidant and anti-inflammatory effects. Animal and human studies from our and other groups suggest that supplementation with walnuts in the diet may improve cognition and reduce the risk and/or progression of MCI and AD. In the transgenic AD mouse model (AD-tg), we have reported the beneficial effects of a diet with walnuts on memory, learning, motor coordination, anxiety, and locomotor activity. Human clinical trials have also suggested an association of walnut consumption with better cognitive performance and improvement in memory when compared to baseline in adults. Our recent study in AD-tg mice has shown that a walnut-enriched diet significantly improves antioxidant defense and decreases free radicals’ levels, lipid peroxidation, and protein oxidation when compared to a control diet without walnuts. These findings suggest that a diet with walnuts can reduce oxidative stress by decreasing the generation of free radicals and by boosting antioxidant defense, thus resulting in decreased oxidative damage to lipids and proteins. An in vitro study with synthetic Aβ showed that walnut extract can inhibit Aβ fibrillization and solubilize the preformed Aβ fibrils, suggesting an anti-amyloidogenic property of walnuts. Because it takes many years for cognitive impairment and dementia to develop, we suggest that early and long-term dietary supplementation with walnuts may help to maintain cognitive functions and may reduce the risk of developing, or delay the onset and/or slow the progression of, MCI and dementia by decreasing Aβ fibrillization, reducing oxidative damage, increasing antioxidant defense, and decreasing neuroinflammation. Furthermore, several animal and human studies have suggested that walnuts may also decrease the risk or progression of other brain disorders such as Parkinson’s disease, stroke, and depression, as well as of cardiovascular disease and type 2 diabetes. Together, these reports suggest the benefits of a walnut-enriched diet in brain disorders and in other chronic diseases, due to the additive or synergistic effects of walnut components for protection against oxidative stress and inflammation in these diseases.


Walnuts for teenagers? 

That’s Nuts! Eating Walnuts Regularly Improves Cognitive Development and Psychological Maturation in Teens

Summary: Teens who added walnuts to their diet for 100 days showed improvements in attention function, and for those with ADHD, frequent walnut consumption was associated with improvements in behavior. Researchers also noted an increase in fluid intelligence in those who frequently consumed walnuts as part of their daily diet.


Walnuts May Help Teens with Maturity, Thinking, and Attention


Effect of walnut consumption on neuropsychological development in healthy adolescents: a multi-school randomised controlled trial


Omega-3 fatty acids are critical for neuropsychological functioning. Adolescence is increasingly believed to entail brain vulnerability to dietary intake. The potential benefit on adolescent neurodevelopment of consuming walnuts, a source of omega-3 alpha-linolenic acid (ALA), remains unclear.


We conducted a 6-month multi-school-based randomised controlled nutrition intervention trial to assess whether walnut consumption has beneficial effects on the neuropsychological and behavioural development of adolescents. The study took place between 04/01/2016 and 06/30/2017 in twelve different high schools in Barcelona, Spain ( Identifier: NCT02590848). A total of 771 healthy teenagers aged 11–16 years were randomised into two equal groups (intervention or control). The intervention group received 30 g/day of raw walnut kernels to be incorporated into their diet for 6 months. Multiple primary endpoints concerning neuropsychological (working memory, attention, fluid intelligence, and executive function) and behavioural (socio-emotional and attention deficit hyperactivity disorder [ADHD] symptoms) development were assessed at baseline and after intervention. Red blood cell (RBC) ALA status was determined at baseline and 6 months as a measure of compliance. Main analyses were based on intention-to-treat using a linear mixed-effects model. A per-protocol effect of the intervention was analysed using inverse-probability weighting to account for post-randomisation prognostic factors (including adherence) using generalised estimating equations.


In intention-to-treat analyses, at 6 months there were no statistically significant changes between the intervention and control groups for all primary endpoints. RBC ALA (%) significantly increased only in the intervention group, coefficient = 0.04 (95% Confidence Interval (CI) = 0.03, 0.06; p < 0.0001). The per-protocol (adherence-adjusted) effect on improvement in attention score (hit reaction time variability) was −11.26 ms (95% CI = −19.92, −2.60; p = 0.011) for the intervention group as compared to the control group, improvement in fluid intelligence score was 1.78 (95% CI = 0.90, 2.67; p < 0.0001), and reduction of ADHD symptom score was −2.18 (95% CI = −3.70, −0.67; p = 0.0050).


Our study suggested that being prescribed eating walnuts for 6 months did not improve the neuropsychological function of healthy adolescents. However, improved sustained attention, fluid intelligence, and ADHD symptoms were observed in participants who better complied with the walnut intervention. This study provides a foundation for further clinical and epidemiological research on the effect of walnuts and ALA on neurodevelopment in adolescents.  

Walnuts for Autism? 

I did find a case study from the Middle East putting forward reasons why walnuts and pumpkin may benefit some types of autism.  It was not a robust study, but I was surprised to find anything at all on this subject. 

Effects of Walnut and Pumpkin on Selective Neurophenotypes of Autism Spectrum Disorders: A Case Study

Special diets or nutritional supplements are regularly given to treat children with autism spectrum disorder (ASD). The increased consumption of particular foods has been demonstrated in numerous trials to lessen autism-related symptoms and comorbidities. A case study on a boy with moderate autism who significantly improved after three years of following a healthy diet consisting of pumpkin and walnuts was examined in this review in connection to a few different neurophenotypes of ASD. We are able to suggest that a diet high in pumpkin and walnuts was useful in improving the clinical presentation of the ASD case evaluated by reducing oxidative stress, neuroinflammation, glutamate excitotoxicity, mitochondrial dysfunction, and altered gut microbiota, all of which are etiological variables. Using illustrated figures, a full description of the ways by which a diet high in pumpkin and nuts could assist the included case is offered.

This case study does not support broad food treatments as a treatment for ASD, but it does imply that specialized dietary interventions over time may play a role in the management of certain ASD symptoms, functions, and clinical domains. The pumpkin/walnut healthy diet improved nutritional status, presumably increasing the brain’s ability to function and learn by reducing oxidative stress, neuroinflammation, glutamate excitotoxicity, mitochondrial dysfunction, and altered gut microbiota, all of which are etiological mechanisms behind the clinical presentation of ASD.   

Impact of Nut Consumption on Cognition across the Lifespan 

Cognitive health is a life-long concern affected by modifiable risk factors, including lifestyle choices, such as dietary intake, with serious implications for quality of life, morbidity, and mortality worldwide. In addition, nuts are a nutrient-dense food that contain a number of potentially neuroprotective components, including monounsaturated and polyunsaturated fatty acids, fiber, B-vitamins, non-sodium minerals, and highly bioactive polyphenols. However, increased nut consumption relates to a lower cardiovascular risk and a lower burden of cardiovascular risk factors that are shared with neurodegenerative disorders, which is why nuts have been hypothesized to be beneficial for brain health. The present narrative review discusses up-to-date epidemiological, clinical trial, and mechanistic evidence of the effect of exposure to nuts on cognitive performance. While limited and inconclusive, available evidence suggests a possible role for nuts in the maintenance of cognitive health and prevention of cognitive decline in individuals across the lifespan, particularly in older adults and those at higher risk. Walnuts, as a rich source of the plant-based polyunsaturated omega-3 fatty acid alpha-linolenic acid, are the nut type most promising for cognitive health. Given the limited definitive evidence available to date, especially regarding cognitive health biomarkers and hard outcomes, future studies are needed to better elucidate the impact of nuts on the maintenance of cognitive health, as well as the prevention and management of cognitive decline and dementia, including Alzheimer disease.



We are told in dietary advice from public health authorities that we should include nuts in our daily diet. The suggested daily amount is about 30 grams (1 ounce).

If you had to choose one nut, it looks like the walnut is the one most likely to help the brain.

Teenagers with ADHD are suggested to benefit in the research from Spain.

Abha Chauhan over in New York is a proponent of walnuts for potentially slowing down Alzheimer’s disease.

Whether walnuts may benefit some with autism is an open question, but there are reasons to believe that it should. Over in Abu Dhabi one autism practitioner is suggesting combining walnuts with pumpkin for optimal effect. 

Ensuring healthy aging with diet and exercise is actually very straight forward, but most people still choose not to do it.

Treating severe autism is much more hit and miss, but many of those who persevere see good results.