What Changes Might Occur in the Brain After Eating Walnuts for Six Months?
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When you hear the word “walnuts,” what comes to mind? Many people may immediately think of two words: *brain food*! But what exactly is the nutritional value of walnuts? Can eating walnuts really boost brain function? Let’s take a closer look today.
Eating Walnuts for Six Months Can Indeed Change the Brain
In April 2023, a six-month randomized controlled nutrition intervention trial published in *The Lancet* sub-journal provided us with preliminary answers to whether eating walnuts can benefit the brain.
The study involved 942 middle school students aged 11–16. After screening, 771 adolescents were included in the analysis and randomly divided into two groups:
- The control group received no intervention.
- The experimental group consumed a 30g bag of walnuts (about 3–4 whole walnuts) daily for six months.
After observation, researchers found that 133 participants who demonstrated good adherence (eating walnuts for more than 100 days, though not necessarily continuously) had slightly higher red blood cell α-linolenic acid levels, improved attention, and noticeable behavioral improvements for adolescents with symptoms of attention deficit hyperactivity disorder (ADHD). This was reflected in greater focus during class and enhanced fluid intelligence-related functions, such as perception, memory, processing speed, and reasoning ability.
For adolescents with good adherence to eating walnuts over six months, the results suggest that walnuts indeed acted as “brain food.” Researchers concluded that regularly eating walnuts (more than three servings per week, approximately 10 walnuts) may improve sustained attention, fluid intelligence, and ADHD symptoms. However, no significant effect was observed on the neurodevelopment of healthy adolescents.
Beyond the research findings, walnuts do contain many nutrients that are beneficial for the brain. For example:
- Protein: Essential for brain composition.
- Carbohydrates: Provide energy for brain function.
- Polyunsaturated fatty acids: α-linolenic acid can convert to DHA in the body, promoting brain health.
However, it’s important to note that while the study shows long-term walnut consumption can benefit brain function, you shouldn’t expect walnuts to increase your IQ!
What Nutrients Do Walnuts Contain?
1. Protein
Walnuts contain 14.9g of protein per 100g. While not the highest among nuts, walnuts offer a variety of amino acids. Research shows walnut protein contains 18 amino acids, including 8 essential amino acids, which account for 26.98%–30.38% of the total amino acids—beneficial for growth and development.
2. Unsaturated Fatty Acids
Walnuts are high in fat, with a content of 58.8g per 100g. Most of this is polyunsaturated fatty acids, which account for 76.2% of the total fatty acids. Linolenic acid and linoleic acid account for 12.2% and 64% of total fatty acids, respectively. Although walnuts contain less α-linolenic acid than flaxseeds, they still surpass other nuts. This component can convert to DHA in the body, which benefits brain and retina health, although the conversion rate is generally low.
3. Vitamin E
Walnuts are rich in vitamin E, containing 43.2mg per 100g, about 1.2 times higher than hazelnuts. Vitamin E has strong antioxidant properties, supports fertility, and maintains normal immune function.
4. Antioxidants
Walnuts are packed with antioxidants, including polyphenols and flavonoids. An analysis of walnut skins showed that gallic acid is the most abundant polyphenol, while rutin is the most prominent flavonoid.
Most antioxidant compounds are found in the walnut skin, which helps fight inflammation and remove excess free radicals. However, due to the high phenolic content, walnut skin has a bitter taste. If you can tolerate it, it’s best to eat walnuts with the skin on.
Other Health Benefits of Walnuts Beyond Brain Function
1. Improving Blood Lipids
A 2018 meta-analysis of 26 clinical trials involving 1,059 participants found that diets incorporating walnuts significantly reduced plasma triglyceride levels by 5.52%, LDL cholesterol (bad cholesterol) by 3.73%, and total cholesterol by 3.25%. These improvements are crucial for preventing hyperlipidemia and reducing the risk of atherosclerosis and cardiovascular disease.
A 2022 meta-analysis of 13 intervention trials across the United States, Germany, Iran, the UK, Spain, and China confirmed that walnut intake significantly improves serum triglyceride, total cholesterol, and LDL levels. The recommended daily walnut intake ranges from 15–64g for healthy individuals and 30–99g for overweight or dyslipidemic individuals.
2. Preventing Diabetes
High nut consumption, especially walnuts, is associated with a reduced risk of diabetes and obesity. Regular nut intake (about once daily) can be part of a healthy diet to prevent obesity and type 2 diabetes.
3. Promoting Sleep
Melatonin, a hormone secreted by the brain’s pineal gland, naturally induces sleep. However, stress and lifestyle factors often disrupt melatonin production, causing insomnia. Walnuts are rich in melatonin. Animal studies show that walnut consumption can quadruple blood melatonin levels. People with poor sleep quality may benefit from regularly eating walnuts.
4. Relieving Anxiety
Walnuts contain a significant amount of α-linolenic acid, which has neuroprotective effects. Research indicates that α-linolenic acid can alleviate anxiety symptoms, ease emotional tension, and reduce stress.
Four Tips for Eating Walnuts
Although walnuts are beneficial for health, they must be consumed properly. Here are four tips for eating walnuts healthily:
1. Choose Plain Walnuts
Flavored walnuts, such as sweet caramelized or salty roasted ones, are often high in sugar or salt. Regular consumption can negatively impact health, increasing the risk of tooth decay, obesity, and hypertension. Plain walnuts or unshelled walnuts are the best choices.
2. Eat Them with the Skin On
Walnuts typically have a dark brown skin, which many people dislike due to its bitterness. However, the skin contains higher antioxidant levels. If you want to maximize the health benefits, eat walnuts with the skin.
3. Store Them Properly
Walnuts are rich in polyunsaturated fatty acids, which can oxidize and turn rancid. To avoid this, buy in small quantities and store them sealed in a refrigerator. Unshelled walnuts are even better—store them in a cool, dry place and open them as needed. Never eat moldy walnuts.
4. Control Your Intake
While nuts can help prevent obesity, overeating is counterproductive. It’s recommended to consume 50–70g of nuts per week, averaging 10g daily. If you exceed this amount, reduce cooking oil or replace portions of pork or beef with walnuts to balance saturated and polyunsaturated fat intake, reducing the risk of coronary heart disease.
FAQs About Walnuts
Are Walnuts Tree Nuts?
Yes, walnuts are classified as tree nuts because they grow on trees and are enclosed in a hard shell. They belong to the tree nut family, which also includes almonds, cashews, and hazelnuts.
Do Walnuts Expire?
Walnuts don't technically expire, but they can go rancid over time due to their natural oils. This causes a change in taste, making them unpleasant to eat.
Are Walnuts Keto?
Yes, walnuts are considered keto-friendly because they are high in healthy fats and low in carbohydrates. However, they can expire over time, especially due to their fat content, which can go rancid if not stored properly. To keep them fresh longer, store walnuts in an airtight container in the fridge or freezer. Always check for a sour smell or bitter taste as signs they may have gone bad.
Are Walnuts Fattening?
Walnuts are a high-energy food, rich in healthy fats and calories. While they provide numerous health benefits, eating them in excess can contribute to weight gain. Moderation is key to enjoying walnuts as part of a balanced diet without affecting your weight.
Are Walnuts Gluten Free?
Yes, natural, unprocessed walnuts are gluten-free. They are a naturally occurring food that does not contain gluten, which is found in wheat, barley, and rye. However, if walnuts are processed or flavored, there’s a risk of gluten contamination, so it’s important to check the label.
Do Walnuts Have Omega 3?
Yes, walnuts are an excellent source of omega-3 fatty acids, specifically alpha-linolenic acid (ALA), which is a plant-based form. They are the only tree nut that provides a significant amount of ALA, making them a great choice for boosting omega-3 intake.
Are Walnuts High In Potassium?
Yes, walnuts contain a moderate amount of potassium, providing about 385mg per 100g. While not as high as foods like bananas or potatoes, they still contribute to your daily potassium intake. Including walnuts in your diet can help support overall nutrient balance.
