A new study, published in the Journal of Nutritional Biochemistry, suggests that omega-3 fatty acids and other compounds in walnuts may reduce inflammation in bowel cancer cells.

They also reduce blood supply to the tumour, significantly slowing down its growth.

Previous studies indicate that walnuts have healthful benefit to the heart and that the local delicacy could beat breast cancer, drug resistant microorganisms and mental decline in the elderly.

Earlier study published in March 2015 Tropical Journal of Pharmaceutical Research concluded: “Juglans regia leaf extract induces potent growth inhibitory effects against human prostate cancer cells (PC3) by inducing apoptosis and by altering the cell cycle phase distribution in these cells.

Therefore, the extract may find application in curbing prostate cancer and is a potential complementary and alternative medicinal treatment for this disease.”

The study is titled “Juglans regia Hexane Extract Exerts Antitumor Effect, Apoptosis Induction and Cell Circle Arrest in Prostate Cancer Cells In vitro.”

J. regia belongs to the family Juglandaceae which includes three species: J. nigra, J. cinerea, and J. regia.

Juglans regia commonly known as walnut tree is a well-known member of Juglans genus, constituting an important species of deciduous trees found primarily in temperate areas.

J. regia extract contains ellagitannins which contains anti-cancer agent and with anti-inflammatory properties. The key chemical composition of walnut is juglone (5-hydroxy-1, 4-naphthoquinone), the toxic compound, which is found only in green and fresh walnuts, but such property disappear in dried leaves.

Other several phenolic compounds with antioxidant properties have been identified in J. regia leaves. Walnut leaves are considered a source of healthcare compounds, and have been extensively used in traditional medicine for treatment of skin inflammations, hyperhidrosis and ulcers and for its anti-diarrheal, anti-helmintic, antiseptic and astringent properties.

The African walnut is botanically known as Tetracarpidium conophorum and belongs to the plant family Euphorbiaceae. In southern Nigerian ethnomedicine, it is used as a male fertility agent and the leaves are used for the treatment of dysentery and to improve fertility in males. It is known as ukpa (Igbo) and awusa or asala (Yoruba). African walnut is known in the littoral and the western Cameroon as kaso or ngak.

United States (US) researchers, in the new study, found mice fed a diet high in walnuts had tumours containing ten times the amount of omega-3s than a control group.

Bowel cancer, also called colorectal cancer, is the third most common type of cancer worldwide and is the second leading cause of death in Western Countries, after lung cancer.

Research has shown that 30 to 50 per cent of bowel cancer in men, and 20 per cent in women can be prevented by changing to a healthier diet and lifestyle.

The study, carried out by Dr. Christos Mantzoros, of Harvard Medical School, is the first of its kind to analyse the impact of walnuts on micro-ribonucleic acids (miRNA), which control how genes adapt to environmental factors.

Mantzoros said: “Our research demonstrates that a walnut diet causes significant changes in the expression profile of miRNAs in colorectal cancer tissue.

“Compounds in walnuts causes more protective omega-3 fatty acids to congregate in tumour cells.

“While future studies are needed, I am ‘optimistic’ changing the expression of miRNAs have a role in targeting bowel cancer.”

Researchers fed a group of mice the equivalent of two servings (2ozs or around 57g) per day of walnuts for humans, while a second group received a similar control diet without walnuts.

After 25 days researchers found that in walnut-fed mice, key miRNA that may affect cancer cell inflammation, blood supply and proliferation were ‘positively engaged’.

The tumours of mice fed the walnut-containing diet were found to have 10 times the amount of total omega-3 fatty acids compared to the mice fed the control diet.

This included the plant-based alpha-linolenic acid (ALA), a fatty acid critical to various body processes and known for its inflammation reducing properties.

The study, published in the Journal of Nutritional Biochemistry, found that the greater the amount of omega-3 acids, the smaller the tumour, suggesting that ALA may offer some protection.

Tumour growth rate was also significantly slower in the walnut group compared to the control group, but the scientists say that because the study was conducted on animals the results won’t necessarily be the same for people.

Walnuts are the only nut that contain a significant source of ALA – 2.5 grams per ounce – as well as a variety of antioxidants, (3.7 mmol/ounce), and numerous vitamins and minerals.

Indeed, previous studies had shown that African walnut prevents heart disease. They suggested eating walnuts at the end of a meal might help cut the damage that fatty food can do to the arteries.

It is thought that the nuts are rich in compounds that reduce hardening of the arteries, and keep them flexible. Phytochemical analysis indicates that African walnuts contain ingredients such as omega-3 fatty acids, antioxidants and phytosterols that may all reduce the risk of the disease.

Most of the studies on the plant have been on the nutritive value of the seeds, which is a snack and delicacy. Two isolectins, Agglutin I and II were characterised from the seed extract.

The presence of oxalates, phytates and tannins as well as proteins, fibre, oil and carbohydrates in African walnut has been reported.

According to a study presented at the United States American Association for Cancer Research yearly meeting, mice fed the human equivalent of two ounces (56.7g) of walnuts per day developed fewer and smaller tumours.

Researcher, Dr. Elaine Hardman, of Marshall University School of Medicine, said although the study was carried out in mice, the beneficial effect of walnuts was likely to apply to humans too.

She said: “We know that a healthy diet overall prevents all manner of chronic diseases. It is clear that walnuts contribute to a healthy diet that can reduce breast cancer.”

In the latest study, mice were either fed a standard diet, or the walnut-based diet. The animals fed walnuts developed fewer tumours, and those that did arise took longer to develop and were smaller. Molecular analysis showed that omega-3 fatty acids played a key role, but other parts of the walnut contributed as well.”

Meanwhile, Nigerian researchers have examined the antimicrobial potential of extracts and fractions of the African walnut.

E. O. Ajaiyeoba and D. A. Fadare of the Department of Pharmacognosy, Faculty of Pharmacy, University of Ibadan, Ibadan, found that African walnut has a high potential as an antimicrobial medicinal plant.

Also, an animal model study by the United States Agricultural Research Service (ARS) suggests that adding a moderate, but not high, amount of walnuts to an otherwise healthy diet may help older individuals improve performance on tasks that require motor and behavioural skills.

The study was conducted by researchers with the Jean Mayer USDA Human Nutrition Research Centre on Ageing (HNRCA) at Tufts University in Boston, Mass., United States.

Neuroscientist James Joseph, psychologist Barbara Shukitt-Hale and co-authors Lauren Willis and Vivian Cheng reported the study in the British Journal of Nutrition.

Researchers, also, suggest that walnut may protect against radiation by removing heavy metals and free radicals from the body.

Recent reports suggest that tincture of black walnut may be effective against radiation exposure. Some unpublished trials showed that the patients who had been “painted” with black walnut or iodine tinctures were just as protected against radiation exposure as the patients who took potassium iodide.

Researchers attribute walnut’s ability to protect against radiation exposure to its chelating ability and high content of antioxidants.

Chelation therapy is the administration of chelating agents to remove heavy metals from the body. For the most common forms of heavy metal intoxication, those involving lead, arsenic or mercury, the standard of care in the United States dictates the use of dimercaptosuccinic acid (DMSA). Other chelating agents, such as 2,3-dimercapto-1-propanesulfonic acid (DMPS) and alpha lipoic acid (ALA), are used in conventional and alternative medicine.

Antioxidants protect the body from damage caused by harmful molecules called free radicals. Many experts believe this damage is a factor in the development of blood vessel disease (atherosclerosis), cancer, and other conditions.

The researchers of the study published in Tropical Journal of Pharmaceutical Research wrote: “Prostate cancer (PC) is the second most wide-spread malignancy and the second leading cause of cancer-related deaths among men in many Western countries including USA.

“Clinically, PC is generally diagnosed in men over 50 years of age; with increasing life expectancy the prevalence of PC is likely to increase worldwide. PC usually develops from androgen-dependent to androgen-independent stage, making anti-androgen therapy unproductive, thus leading to a rise in metastatic potential.

“Suppression of cancer development frequently involves modulation of signal transduction pathways, resulting in alterations in gene expression, arrest in cell cycle progression or apoptosis. Apoptotic cell death represents a universal and intricately efficient suicide pathway, considered as a perfect method for elimination of damaged cells. Recently, the apoptosis signaling systems have been shown to provide encouraging targets for the development of novel anticancer agents. Several plant-derived bioactive compounds are known to be chemo-preventive agents inducing apoptosis in a number of experimental mode is of carcinogenesis. Thus induction of apoptosis is considered as a possible mechanism of chemo preventive agents.

“In this study, the Juglans regia hexane extract was evaluated for its anticancer activity against human prostate PC3 cancer cells. The extract showed a dose-dependent inhibition of the cancer cells with 100 μg/mL of the extract producing the most potent growth inhibition. In order to further study the mechanism of the extract, we evaluated effect of the extract on cell cycle analysis, apoptosis induction using Annexin V binding assay as well