Walnuts: How Many to Eat Daily, Proven Benefits and More

Walnuts: How Many to Eat Daily, Proven Benefits and More

  03 Oct 2018

Walnuts are an extremely nutritious type of seed that grows on the walnut tree. Raw walnuts are full of antioxidants, healthy fatty acids, and many nutrients. Consuming a few walnuts a day is good to keep your brain functioning well, boost your heart health, and have healthy skin.

Many of the health benefits of walnuts come from the fact that they contain iron, selenium, vitamin E, and some B-group vitamins. Walnuts are also a rich source of essential omega-3 fatty acids. In fact, just 3 or 4 walnuts (or 7 walnut halves) could help you meet your daily omega-3 needs.

In this article, you will find out why walnuts are one of the best nuts that you can eat for good health.

What Are Walnuts?

The walnut tree is from the Juglans genus, and grows in many countries that have a temperate climate.

Walnut trees produce a fruit called the walnut, which is actually a seed that is contained in a hard shell. The most common types of walnuts are the Persian Walnut, English Walnut, and the black walnut.

Walnut shells need to be cracked open to get to the edible walnut seed. This process may result in splitting the walnut kernel in half. Walnuts look like wrinkly lobes that are covered by a thin brown skin.

Like most nuts and seeds, walnuts can go bad if not stored correctly. According to the University of California, you can prevent shelled walnuts from going rancid by keeping them in an airtight container in the refrigerator. This can increase the shelf life of walnuts.

The flesh of the walnut and the skin are rich in antioxidants that have tremendous health benefits.

Nutritional Value of Walnuts

When examining the nutritional value of walnuts, it becomes easy to see just why walnuts are so good for you.

Walnuts are good for both men and women because they contain a lot of protein, vitamins, minerals, and antioxidants.

1 oz. (28 g) of walnuts are approximately 14 halves. An ounce of walnuts contains 185 calories , 45 mg magnesium, and nearly 2 g of dietary fiber, which is 8% of your recommended daily fiber intake. 1/4 cup of shelled walnuts contains 164 calories.

1 oz. (28 g) of walnuts (7 walnuts) contains 4.3 g protein.

A serving of 14 walnut halves contains 4 grams of carbohydrates and have a low glycemic index.

A daily serving of walnuts can also be good for your health because they contain healthy fats. Walnuts contain a unique combination of polyunsaturated fatty acids – n-6 (linoleate) and n-3 (linolenate). These healthy fats have been associated with improved cardiovascular health.

As well as containing healthy fatty acids, walnuts are also a good source of vitamins and minerals that can help to keep you healthy. According to the United States Department of Agriculture, 1/4 cup of chopped walnuts (approx. 30 grams) contains 50% of your daily manganese requirements (RDI), 23% of your copper RDI, 11% or your magnesium RDI, and nearly 5% of your iron RDI.

Walnuts contain a lot of antioxidants

One of the reasons that eating 2 or 3 walnuts per day is so good for you is that they are jam-packed with antioxidants.

Most nuts and seeds contain polyphenols – important antioxidants that are necessary for good health. When it comes to antioxidants in walnuts, it seems that walnuts stand out among other nuts.

The journal Critical Reviews in Food Science and Nutrition reported in 2017 that walnuts have strong health-promoting effects. Scientists have discovered that walnuts are one of the most important sources of polyphenols. These antioxidants also help to reduce inflammation and can help prevent various chronic diseases like cancer, cardiovascular disease, and neuro-degenerative diseases.

Walnuts are a rich source of omega-3 fatty acids (ALA)

Because raw walnuts are such a great source of omega-3 fatty acids, you can call walnuts a heart-healthy nut. A one-ounce serving (28 g) of walnuts contains 2.57 gram of beneficial omega-3 fatty acids.

According to scientific research, walnuts contain one of the highest levels of omega-3 of any nut. What’s more, walnuts contain a type of omega-3 fatty acid called alpha-linolenic acid (ALA).

Studies have shown that walnuts are one of the best sources of ALA fatty acids. One study found that consuming a few walnuts daily for 3 weeks significantly increased ALA levels and eicosapentaenoic acids (EPA) levels in the blood.

The rich source of ALA omega-3 in walnuts has significant benefits for your heart health. Studies show that regularly consuming ALA fatty acids lowers your risk of cardiovascular disease.

Why Walnuts are the Nut That Surpasses All Other Nuts

The nutritional value of walnuts means that they are the champion among nuts.

Joe Vinson, PHD, a chemistry professor from the University of Scranton, analyzed different types of raw and roasted nuts. His study concluded that not only should we increase the consumption of nuts, but also that there is a nut that surpasses all its counterparts in terms of the health benefits.

According to Dr. Vinson’s research, walnuts are the best among nuts. They rank better than pistachios, almonds, pecans, cashews, Brazil nuts, hazelnuts, and macadamia nuts.

Vinson’s study showed that walnuts have more polyphenols and a higher antioxidant potency when compared to other nuts that were analyzed. Furthermore, antioxidants from walnuts are thought to be 15 times more potent than vitamin E, which is known as a strong antioxidant. Antioxidants destroy free radicals and thus prevent cell changes that can lead to the development of serious disease.

Other studies have also shown why walnuts surpass other nuts when it comes to the antioxidant content. The Journal of Nutrition reported that walnuts contain more antioxidants per 100 g than other plant-based sources of antioxidants. For example, there is >20 mmol of antioxidants per 100 g of walnuts.

Walnuts vs. almonds

Comparing walnuts with almonds, you can see why walnuts excel in their nutritional content. For example, 100 g of almonds only contain between 0.23 and 0.49 mmol/100 g of antioxidants.

When you compare the omega-3 content of walnuts to almonds, you can see why eating walnuts is so healthy. 1 oz. of almonds (about 23 almonds) only contains 1.7 mg omega-3 fatty acids whereas walnuts contain over 2,500 mg omega-3!

Although almonds contain higher levels of vitamin E than walnuts, walnuts contain more minerals than almonds.

How Many Walnuts to Eat Daily and How to Eat them

One walnut provides you with a portion of healthy fats, proteins, potassium, magnesium, phosphorus, iron and B vitamins and makes for a perfect snack. Dr. Vinson, mentioned previously, estimates that eating just 7 walnuts a day is enough to get all of their potential health benefits.  So you don’t need to consume  large portions of walnuts to enjoy their health benefits.

Walnuts are best consumed raw, as roasting them may affect some of the nutrients that are sensitive to heat. You can soak walnuts overnight before eating them to improve their nutrient profile. You can find more information in my article “Why You Need to Soak Nuts and Seeds“.

There are a lot of nutritional benefits to eating whole walnuts including the skin. Researchers now know that many of the antioxidants in walnuts are found in the skin.  Some websites encourage you to remove the walnut skin (outermost part of shelled walnuts) because it can be slightly bitter, but it is recommended not to remove this antioxidant-rich part.

Benefits of Consuming Walnuts

Let’s look in more detail at the many health benefits you can get from eating 3 or 4 walnuts a day.

Walnuts Promote Healthy Brain Function

Eating walnuts is good for your cognitive function because of their high levels of antioxidants that reduce the effects of inflammation in the brain.

The Journal of Nutrition reported that consuming walnuts helps to lower the oxidative and inflammatory load on brain cells. This can help prevent degenerative brain disease in older persons.

 

Eat more walnuts to help prevent depression

A randomized controlled trial found that consuming walnuts can help to improve your mood. The trial involved men consuming 60 g of ground walnuts per day for 8 weeks. At the end of the trial, scientists found that walnuts helped to improve mood in healthy, non-depressed males.

Other studies have found that a diet rich in fresh vegetables with nuts and seeds can help to counteract depression and improve cognitive function.

 

Walnut consumption may prevent Alzheimer’s disease

Studies show that regularly including walnuts in your diet can help to prevent Alzheimer’s disease.

One trial involving mice found that feeding the equivalent of 14 halves of walnuts a day improved brain function like memory and learning skills. The scientists concluded that walnuts have the potential to reduce the risk or slowing down the progression of Alzheimer’s disease.

 

Consuming walnuts can help improve your memory

The high levels of omega-3 fatty acids in walnuts can also have a positive effect on your memory. One laboratory trial found that walnut supplementation improved memory pathways and improved the sensitivity of serotonin receptors in the brain.

 

Eating walnuts may prevent cognitive decline

One clinical trial lasting 2 years and involving over 700 persons found that consuming between 14 and 30 walnut halves per day helped to prevent cognitive decline. The scientists concluded that eating more walnuts can help to delay age-related degenerative conditions.

Walnut Consumption Helps Improve Your Heart Health

Eating a few walnuts every day benefits your heart because of the high levels of polyphenols and omega-3 fatty acids.

One of the benefits of eating more walnuts for your heart health is that they don’t cause weight gain. A review of 5 human clinical trials found that the unique combination of polyunsaturated acids in walnuts boost cardiovascular health. The researchers noted that walnuts don’t cause weight gain when used as a replacement food.

Another study found that consuming 1/2 a cup of ground walnuts (43 g) for 8 weeks helped to lower the risk of coronary heart disease.

 

Walnuts May Help Reduce Hypertension

Magnesium, potassium, and omega-3 fatty acids in walnuts all play a role in helping to lower blood pressure.

Walnuts also contain significant levels of melatonin – a hormone in blood that is related to blood pressure. Scientists have found that regularly consuming a few walnuts increases levels of melatonin in the blood. This has both an antioxidant effect and helps to lower blood pressure.

The International Journal of Molecular Sciences reported that melatonin helps regulate blood pressure. The ability to lower hypertension is due to the positive effect that melatonin has on the central nervous system.

 

Walnuts Have Compounds That May Lower Cholesterol

Another reason why walnuts are classed as “heart healthy nuts” is that they help lower cholesterol in the blood.

One randomized controlled trial found that a walnut-enriched diet resulted in a decrease of cholesterol levels. 134 women took 43 g of walnuts per day. At the end of 8 weeks, scientists noticed a significant reduction in fasting cholesterol.

A systematic review of 13 scientific studies on the effects of walnuts on cholesterol also found positive results. Consuming more walnuts in the diet results in lower LDL (or, “bad”) cholesterol levels. Also, increasing the intake of walnuts didn’t result in an increase in body mass.

 

Walnuts Can Help to Improve Gut Microbiota

Another reason why walnuts are good for you is that they improve your gastrointestinal health.

The Journal of Nutrition in 2018 published results of a randomized controlled trial on the benefits of walnuts for your gut health. Participants consumed 42 g of walnuts for a 2-week period. Tests on gut microbiota revealed that walnuts helped to increase good gut bacteria.

 

Walnuts Have Anti-Inflammatory Properties

The high levels of polyphenols contained in raw walnuts mean that they are a good nut to help reduce inflammation.

Chronic inflammation has been linked to many diseases like diabetes, cancer, and heart disease.

Researchers have found that eating walnuts causes a type of tannin (ellagitannin) to be released that has anti-inflammatory properties. Many studies have shown that these antioxidants in walnuts have a protective effect against heart disease, cancer, and neurodegenerative diseases.

Other studies have shown that the high levels of both omega-3 and antioxidants make walnuts one of the best nuts for reducing inflammation. Raw walnuts and roasted walnuts have some of the highest antioxidant levels when compared with other tree nuts.

Research has also shown that eating more nuts such as walnuts help to reduce inflammatory markers in the blood.

 

Eating Walnuts May Help You Lose Weight Faster

Because walnuts are high in antioxidants and help improve your metabolic health, walnuts can help you lose weight faster.

Many people tend to shy away from nuts such as walnuts because of their high fat and calorie content.

One study found that using walnuts as a healthy energy source helped boost the effects of a weight-loss diet. The study found that both a standard weight-loss diet and a weight-loss diet enriched with walnuts helped participants lose weight. However, consuming walnuts had a better effect on lowering LDL cholesterol and reducing blood pressure.

Dr. Vinson (mentioned earlier) points out that fats from nuts are polyunsaturated and monounsaturated fats that are healthy and important for the body’s function. They mustn’t be mistaken for the unhealthy fats that clog the arteries and are connected with chronic diseases and weight gain.

Nonetheless, the portions of nuts to consume on a daily basis should remain small. A handful of walnuts will provide you with the much needed nutrients and antioxidants and will protect your body against various conditions.

If you are struggling to lose weight, find out about hidden reasons that can prevent weight loss.

Walnuts Are Good for Managing Diabetes

The nutritional content of walnuts means that they are healthy nuts that can help to manage the symptoms of diabetes.

The journal Diabetes/Metabolism Research and Reviews reported that walnuts help to lower blood glucose levels. Also, regularly consuming walnuts helps to reduce a person’s risk of developing diabetes.

Some studies also indicate that women can benefit from consuming more walnuts as part of a healthy diet. The presence of polyunsaturated fatty acids in walnuts benefits cardio-metabolic health and can prevent type 2 diabetes. One trial found that women who ate at least 28 g of walnuts a week had less of a chance of developing diabetes.

 

Walnuts Benefit Male Reproductive Health

Walnuts have many benefits for men because their ALA omega-3 content helps to improve male reproductive health.

A randomized control dietary intervention trial found that consuming 18 whole walnuts a day helped to improve sperm quality. Researchers noted that after 12 weeks, there was a marked improvement in sperm vitality, morphology, and shape.

Other studies have shown that increasing walnut intake can benefit men’s fertility and prevent oxidative stress that can affect male reproduction ability.

If you are trying to father a child, learn about other ways to improve the lifespan of sperm.

Walnuts Have Cancer Fighting Properties

Various trials have shown that consuming walnuts may help in preventing the development of certain cancers.

Scientists suggest that a combination of many of the beneficial antioxidants in walnuts helps kill off cancer cells. Lab trials on mice have found that tocopherols and other biochemicals can help slow the growth of colon, prostate, and renal cancer. Also, walnut compounds have shown to be effective in reducing the size of breast tumors.

Ellagitannins in walnuts turn into a compound called urolithin in your gut. Some studies have shown that urolithins can help to kill off prostate cancer cells and help prevent prostate cancer.

Unfortunately, there are very few clinical trials on using walnuts to treat cancers in humans. However, many doctors agree that a diet rich in antioxidants and omega-3 fatty acids has many health benefits, including helping to reduce the risk of cancer.

Antioxidants in Walnuts are Great for Healthy Skin

The number of powerful antioxidants in walnuts mean that eating a serving of walnuts every day can boost your skin’s health.

Doctors on WebMD report that you need a good number of vitamins and minerals from your diet for healthy skin. Eating foods rich in antioxidants helps to “feed” your skin from the inside and improve how your skin looks and feels.

One serving of 14 walnut halves contains small amounts of vitamin C, E, K, and B-group vitamins. All of these are essential for skin care. Also, minerals found in walnuts like selenium, copper, and zinc help to reduce the visible appearance of aging.

Research also shows that getting adequate amounts of alpha-lipoic acid (ALA) in your diet is also essential to protect your skin cells from damage.

Walnut Benefits for Your Hair and Scalp

Walnuts also contain vitamins and minerals that can boost the health of your scalp and help to have shiny hair.

The journal Dermatology Practical & Conceptual reports that healthy hair and scalp require minerals such as iron, selenium, and zinc. You also need to have a diet rich in antioxidants and fatty acids. For example, omega-3 is necessary to help promote hair growth. (41)

You can also use a small amount of walnut oil to massage into your scalp to moisturize it and to give your hair a shiny look.

Side Effects and Precautions When Eating Walnuts

Walnuts are tasty nuts or seeds that are very beneficial for your health. Walnut “fruit” contains protein, vitamins, minerals, and is high in healthy fatty acids.

The only side effect that doctors warn from consuming walnuts in reasonable amounts is an allergic reaction. If you suffer from tree nut allergies, you should make sure you are not allergic to walnuts before consuming them. (42)

How to Select Walnuts

  • When you purchase whole walnuts that have not been shelled, choose the ones that feel heavy for their size. Make sure their shells are not cracked or stained, as often this is a sign of mold developing on the nut.
  • Shelled walnuts are usually available in prepackaged containers or in bulk bins. If you purchase them from the bulk section, make sure that the store has a good product turnover to ensure maximal freshness. Whether purchasing walnuts in bulk or in a packaged container avoid those that look wrinkled as they indicate old age. It’s also a good idea to smell the walnuts if you can to ensure that they are not rancid.

How to Store Walnuts

Walnuts are high in polyunsaturated fat, and that makes them extremely perishable. Shelled walnuts should be stored in an airtight container in the refrigerator, where they will keep for six months and even more.

You can also freeze walnuts, where they will last for one year.

Unshelled walnuts should preferably be stored in the refrigerator, although you can also keep them in a cool, dry, dark place where they will stay fresh for up to six months.

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