If you keep eating walnuts for 6 months, your brain may really change!

What do you think of when you mention "walnuts"? Many people may think of two words: "brain nourishment"!

What are the nutritional properties of walnuts? Can eating more walnuts really "nourish the brain"? Let's talk about it in detail today.

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Eat walnuts for 6 months.

The brain really changes!

In April 2023, a six-month randomized controlled nutritional intervention trial was published in a subsidiary of the well-known medical journal The Lancet, which gave us a preliminary answer to the question of "whether eating walnuts can nourish the brain."
The study included 942 middle school students aged 11 to 16. After screening, 771 adolescents were included in the analysis and randomly divided into groups - the control group did not receive any form of intervention; the experimental group received a small bag containing 30g of walnut kernels every day, which is about 3 to 4 walnuts, and ate 1 bag a day for 6 months.

After observation, the researchers found that 133 people had good compliance and ate walnuts for more than 100 days (not necessarily every day). The alpha-linolenic acid status of these adolescents' red blood cells was slightly higher and their attention was enhanced. It had a significant improvement effect on the behavior of some adolescents with symptoms of attention deficit hyperactivity disorder, which was manifested in paying more attention to teachers in class and an increase in fluid intelligence-related functions, such as perception, memory, calculation speed, and reasoning ability.

It seems that for adolescents who have been eating walnuts for 6 months with good compliance, walnuts do play a role in "brain nourishment". The researchers also believe that eating walnuts regularly (more than 3 servings per week, about 10 walnuts) may lead to improvements in sustained attention, fluid intelligence and ADHD symptoms, but it has no significant effect on the neurodevelopment of healthy adolescents.

Putting aside the research, walnuts do contain many nutrients that the brain needs. For example, protein is a component of the brain; carbohydrates provide energy for the brain to function; and the polyunsaturated fatty acid α-linolenic acid can be converted into DHA in the body, which helps brain health.

But it should be reminded that although the above research shows that eating walnuts for a long time is helpful for "brain supplementation", don't expect to improve your IQ by eating walnuts!

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What nutrients do walnuts have?

Walnuts, also known as walnuts, are widely planted in my country. As of 2020, my country's walnut planting area ranks first in the world, which shows how popular walnuts are in my country. It can be made into art, played with walnuts, and eaten, killing three birds with one stone! The nutritional value of walnuts is really good. It is known as the "longevity fruit" and "treasure of health".

1

protein

The protein content of walnuts is 14.9g/100g. Although it is not very good among nuts, it is rich in amino acids. Studies have shown that walnut protein contains 18 kinds of amino acids, including 8 essential amino acids for the human body, accounting for 26.98%~30.38% of the total amino acids, which is beneficial to growth and development.

2

Unsaturated fatty acids

Walnuts have a fat content of up to 58.8g/100g, mainly polyunsaturated fatty acids, accounting for about 76.2% of the total fatty acids, while linolenic acid and linoleic acid account for 12.2% and 64% of the total fatty acids, respectively. Although the α-linolenic acid content in walnuts is not as high as that in flaxseeds, it is much higher than that in other nuts. This ingredient can be converted into DHA in the body, which is beneficial to the health of the brain and retina, but the conversion rate is generally low.

3

Vitamin E

The vitamin E content of walnuts is relatively prominent among nuts, up to 43.2mg/100g, nearly 1.2 times that of hazelnuts. Vitamin E has strong antioxidant properties and is also an essential nutrient for maintaining fertility and normal immune function.

4

Antioxidant ingredients

Walnuts are rich in antioxidants, including total phenols and flavonoids. An analysis of the phenolic and flavonoids in the seed coat of fresh walnuts found that gallic acid was the highest in phenolic substances and ferulic acid was the lowest; rutin was the highest in flavonoids.

And most of the antioxidants are in the seed coat of walnut fruit . These ingredients are antioxidant and can help our body fight inflammation and remove excess free radicals. However, because the seed coat of walnut fruit contains high levels of phenolic substances, it has a distinct astringency. If you can accept it, it is best to eat it with the skin.

In addition, I have to remind everyone: walnut ≠ pecan .

The walnut we usually talk about is a nut of the genus Juglans, while the hickory nut is not a "mountain walnut", it is also called a small walnut, and is a member of the genus Juglans. Hickory nuts are much smaller than walnuts, with thicker skin and lower edible parts. The edible part of walnuts is 43%, while the edible part of hickory nuts is only 24%.

Image source: iPlant

There are also significant nutritional differences between the two. In comparison, walnuts contain higher levels of linolenic acid, dietary fiber, potassium, and selenium, while pecans contain higher levels of protein, vitamin E, and magnesium.

Note: The linolenic acid data of pecans is for cooked pecans. Source: Created by the author

Walnuts are not only good for the brain

What other benefits does it have for the body?

Walnuts are so nutritious, so when you eat them, don’t just think about whether they can “nourish your brain”. Eating walnuts regularly has many other benefits to your body!

1

Improve blood lipids

A 2018 data analysis of 26 clinical trials involving 1,059 subjects found that compared with the control group that did not eat walnuts every day, the diet with walnut intervention significantly reduced plasma triglyceride (TG) levels by 5.52%, low-density lipoprotein cholesterol (bad cholesterol) levels by 3.73%, and total cholesterol levels by 3.25%.

The decrease in these indicators is of great significance for preventing hyperlipidemia, and can also further reduce the risk of atherosclerosis and cardiovascular disease.

A 2022 meta-analysis of 13 intervention trials involving populations in the United States, Germany, Iran, the United Kingdom, Spain, and China explored the effects of walnut intake on blood lipid levels. The study found that walnut intake was significantly associated with improvements in serum triglycerides, total cholesterol, and bad cholesterol levels.

In the study, the daily walnut consumption for healthy people was 15 to 64 grams, while for people with overweight, obesity and dyslipidemia, the daily walnut consumption was 30 to 99 grams.

2

Preventing diabetes

A study in the American Journal of Clinical Nutrition mentioned that a high intake of nuts (especially walnuts) is associated with a lower risk of diabetes and also a lower risk of obesity. Therefore, you can eat nuts regularly (about once a day) as part of a healthy diet to prevent obesity and type 2 diabetes.

3

May Promote Sleep

As we all know, melatonin is a hormone secreted by the pineal gland in the brain that can naturally induce sleep. However, due to physical or work reasons, the melatonin secretion of many people is affected, making it difficult to fall asleep.
Walnuts are foods rich in melatonin. A study found that after feeding animals with walnuts, the melatonin content in their blood could be quadrupled. People with poor sleep may find that eating walnuts regularly may help them sleep better, so why not give it a try?

4

Relieve anxiety

Among nuts, walnuts have a relatively high content of α-linolenic acid. Studies have shown that α-linolenic acid has a neuroprotective effect, can reduce anxiety symptoms, relieve emotional tension, and reduce stress.

4 Tips for Eating Walnuts

Although eating walnuts is good for your health, you have to choose the right way to eat them. Here are 4 tips on how to eat walnuts in a healthy way. Be sure to check them out!

1

Choose original walnut

There are many flavors of walnuts on the market now, such as sweet amber walnut kernels and salty pepper and salt walnut kernels. These walnut kernels are generally high in sugar or salt. Eating them often is not good for your health and will increase the risk of diseases such as dental caries, obesity, and high blood pressure.

The most recommended are original walnut kernels or whole walnut kernels in shells.

2

Best eaten with the skin

Normally, the surface of walnut kernels has a dark brown walnut skin, which tastes a bit bitter. Many people don't like to eat it. There are also peeled walnuts on the market, which are white and clean. If you want to get more antioxidants in walnuts, eat them with the skin.

3

Note how to save

Walnut kernels are rich in polyunsaturated fatty acids, which are easily oxidized and rancid, and have a rancid smell. Therefore, it is recommended to buy small amounts each time and store them in a sealed and refrigerated place. It is even better if you can buy shelled walnuts. Store them in a cool and dry place and open them before eating. Do not eat moldy walnuts!

4

Control the amount

Although eating nuts regularly can help prevent obesity, you should not eat too much. The Dietary Guidelines for Chinese Residents recommends eating 50-70g of nuts per week, an average of 10g per day, equivalent to 1 large paper-shell walnut or 2-3 pecans. If you eat too much, you can appropriately reduce the amount of cooking oil, or use walnuts to replace some pork and beef, so as to achieve partial replacement of saturated fatty acid intake with polyunsaturated fatty acids, which can reduce the risk of coronary heart disease.

The weight of a paper-shell walnut is about 9g. Image source: provided by the author

Small walnuts, big benefits! Eating walnuts every day will make your blood lipid levels healthier, maintain your weight better, reduce anxiety, and gradually reduce stress. It may also make you more focused, have a better memory, and have stronger reasoning ability.

Start eating walnuts!

References

[1] Pinar-Martí, Ariadna et al. "Effect of walnut consumption on neuropsychological development in healthy adolescents: a multi-school randomized controlled trial." EClinicalMedicine vol. 59 101954. 6 Apr. 2023, doi:10.1016/j.eclinm.2023.101954

[2] Wu Ping, Zhou Jisong, Deng Qianchun, et al. Structure, nutritional value, preparation, functional properties and application of walnut protein in food [J/OL]. Food Science: 1-12 [2024-01-05]. http://kns.cnki.net/kcms/detail/11.2206.TS.20231225.1345.030.html.

[3] Yang Yuexin. Chinese Food Composition Table 6th Edition Volume 1[M]. Peking University Medical Press, 2018

[4] Zhang Pengfei, Zhao Zhiyuan, Song Yuqin, Liu Yaling, Liu Qunlong. Analysis of total phenolic content in walnut fruit[J]. Journal of Shanxi Agricultural University: Natural Science Edition, 2013, 33(4): 324-327341

[5]Guasch-Ferré, Marta et al. "Effects of walnut consumption on blood lipids and other cardiovascular risk factors: an updated meta-analysis and systematic review of controlled trials." The American journal of clinical nutrition vol. 108,1 (2018): 174-187. doi:10.1093/ajcn/nqy091

[6] Alshahrani SM, Mashat RM, Almutairi D, Mathkour A, Alqahtani SS, Alasmari A, Alzahrani AH, Ayed R, Asiri MY, Elsherif A, Alsabaani A. The Effect of Walnut Intake on Lipids: A Systematic Review and Meta-Analysis of Randomized Controlled Trials. Nutrients. 2022 Oct 23;14(21):4460.

[7]Jackson, Chandra L, and Frank B Hu. “Long-term associations of nut consumption with body weight and obesity.” The American journal of clinical nutrition vol. 100 Suppl 1,1 (2014): 408S-11S. doi:10.3945/ajcn.113.071332

[8] Zhang Ting, Du Qian, Li Yong. Research progress on nutritional components and health functions of walnuts[J]. Chinese Food and Nutrition, 2018, 24(7): 64-69

Planning and production

This article is a work of Science Popularization China-Starry Sky Project

Produced by Science Popularization Department of Science Popularization China

Producer: China Science and Technology Press Co., Ltd., Beijing Zhongke Xinghe Culture Media Co., Ltd.

Author: Xue Qingxin, registered nutritionist

Review | Ruan Guangfeng, Deputy Director of Kexin Food and Health Information Exchange Center

Planning丨Lin Lin

Editor: Lin Lin