Hazelnuts

From ancient European traditions to Italian liqueur, to a very famous nutty-chocolate spread, hazelnuts have been in the spotlight for thousands of years and for many different commercial, nutritional and symbolic reasons.

Historical evidence of hazelnut harvesting has been found in Scotland and parts of Europe during the Stone Age. In the 1970’s, carbonised hazelnuts were located near Pompeii in Italy from around the 1st Century CE.

Hazelnuts are the fruit from the tree (corylus avellana) and at first grow in pale green husks then once mature will fall to the ground ready for harvest. The largest worldwide producers of hazelnuts come from Turkey. Other big producers are from regions in Italy and Oregon in the U.S.

Shelled hazelnuts are about the size of a grape with a distinctive toasty flavour, even if they're raw. They can be enjoyed fresh, roasted, chopped or in hazelnut butter.

A pile of hazelnuts

Hazelnuts in Ancient Folklore & Fertility

In 16th century France, there was a superstitious belief that striking a cow 3 times with a hazel tree branch would cause the cow to give milk for a year. In Norse mythology, hazelnuts have also been revered as a symbol of fertility and life. In Germanic traditions, the bride would hand out hazelnuts to wedding goers after the wedding had been consummated.

Storing Hazelnuts

Unshelled hazelnuts can be stored in a cool, dry spot in the pantry for many years. Shelled hazelnuts should remain in an airtight container and hazelnut butter once opened should live in the fridge.

Hazelnut health benefits at a glance:

  • Proanthocyanidin & Flavonoid Polyphenols - protects against DNA damage and boosts immune function
  • Essential fatty acids - Supports nervous system, supports cardiovascular health, promotes favourable cholesterol profiles and blood pressure
  • High protein content - supports immune and hormone health
  • Folate - Protects DNA and aids reproductive function
  • High Vitamin E - Supports skin health, prevents lipid peroxidation and helps immune function
  • B vitamins - energy production, neurotransmitter health, liver detoxification
  • Manganese, selenium, calcium, copper, zinc - cofactors for intracellular and extracellular antioxidants

Cardiovascular Health

A 2016 meta-analysis with 425 participants was conducted to evaluate the effects of hazelnuts on cholesterol and body weight. It looked at several trials to assess the overall effect of hazelnuts on these parameters. Similar to almonds and olive oil, the monounsaturated fat content in hazelnuts accounts for the favourable cardiovascular outcomes, with particular regard to the reduction in LDL cholesterol, triglycerides and maintenance of BMI.

The researchers concluded that hazelnut supplementation was ‘consistently better’ compared to any of the control diets within each of the nine studies.

They also stated that the synergistic effect of phenolic compounds, trace elements and vitamin E all play a role in reducing oxidative stress and therefore maintaining cardiovascular health.

This Bayesian study made the important assertion that to achieve the healthy cardiovascular targets set out in the study parameters, individuals would need to eat an average of 50g of hazelnuts per day.

In reality, this may not be practical for most people, however the research is compelling enough to justify including hazelnuts as a healthy snack option.

A small bowl of hazelnuts on a table

Cocoa and hazelnut health effects

A small crossover study with a group of smokers measured the beneficial cardiovascular effects of consuming cocoa hazelnut spread. The results showed that antioxidants from vitamin E in hazelnuts and the polyphenols in both combined helped to lower oxidative stress markers and ultimately increase nitric oxide, which helps relax blood vessels in the participants.

Memory & brain health

Hazelnuts featured in traditional Persian medicine as a treatment in protection against brain atrophy and to improve cognitive performance. Modern science now supports what these ancient cultures long believed.

Empirical studies show hazelnut consumption has favourable effects on memory. The specific nutrient profile including essential fats, vitamin E and B vitamins are all neuroprotective, which mean hazelnuts help preserve brain tissue by preventing its degradation from environmental and internal stresses.

A 16-week intervention including hazelnuts from Oregon, USA assessed temporal lobe changes and vitamin E and magnesium status amongst a small group of elderly participants. 57g per day of hazelnuts were consumed for the study duration. Anthropomorphic (weight and skin fold) measurements were taken along with blood samples to determine concentrations of various nutrients.

The researchers found alpha tocopherol (vitamin E) and serum magnesium were increased at the end of the study. Along with this, fasting glucose and LDL cholesterol levels were also decreased in participants. These findings mean hazelnuts should be considered a healthful addition to support brain health, particularly in populations prone to cognitive decline such as the elderly.

A large bowl of hazelnuts on a kitchen table

Hazelnut allergy

Emerging information from a 2019 literature review on the prevalence of hazelnut allergy concluded that the occurrence is rising in children and medical testing is becoming more sensitive in its diagnosis. The direct causes of all tree nut allergies are poorly understood, yet diagnostic methods are improving as the techniques become more sensitive and accurate.

A 2016 literature review found among 36 studies, the prevalence of tree nut allergies varied from region and each nut. Europe has a higher prevalence of hazelnut allergy, while the UK and US have higher walnut, cashew and almond allergies, respectively. In a 2020 report, hazelnut allergy appears to present differently in children compared to adults, according to the research. Children exhibit a true IgE-mediated response, sometimes involving the airways and skin irritations. Cross-reactivity with birch pollen, which is related to hazel trees, occurs more often in adults and presents with itchy, watery eyes.

I have not personally observed isolated hazelnut allergy in patients, perhaps because as the research suggests it occurs more widely in Europe than Australia. However it wouldn’t be surprising if it was at a subclinical level for some people or as a result of cross-reactivity with pine or birch allergies. Again, if you have concerns, consult a GP or your health care provider.

Brussels Sprouts with Beurre Noisette

Fall in love with French-style Brussels sprouts in a beurre noisette sauce. Enjoy as a side with your favourite roast meat or grilled fish. 

Recipe

Ingredients

  • 1 tbsp. Butter
  • 400g brussels sprouts, quartered
  • ¼ cup chopped hazelnuts
  • ½ tsp. Salt
  • Cracked black pepper
  • 3 tbsps. water

Method

  1. Preheat oven to 200 degrees
  2. Place butter on a baking dish and roast until browned, around 5 minutes
  3. Add Brussels sprouts and hazelnuts to brown butter. Season with salt and pepper and mix with a spatula to coat evenly.
  4. Continue to roast for another 15 minutes, add water halfway through. Ensure they aren’t burning.
  5. Roast until Brussels sprouts are browned and tender. Enjoy

Article References

Adamo, M., Labate, A. M., Ferrulli, A., Macrì, C., Terruzzi, I., & Luzi, L. (2018). Effects of hazelnuts and

cocoa on vascular reactivity in healthy subjects: a randomised study. International journal of food

sciences and nutrition, 69(2), 223–234. https://doi.org/10.1080/09637486.2017.1348492

 

Alasalvar, C., & Bolling, B. W. (2015). Review of nut phytochemicals, fat-soluble bioactives, antioxidant

components and health effects. The British journal of nutrition, 113 Suppl 2, S68–S78.

https://doi.org/10.1017/S0007114514003729

 

Arslan, J., Gilani, A. U., Jamshed, H., Khan, S. F., & Kamal, M. A. (2020). Edible Nuts for Memory. Current

pharmaceutical design, 26(37), 4712–4720. https://doi.org/10.2174/1381612826666200806095649

 

Bolling, B. W., Chen, C. Y., McKay, D. L., & Blumberg, J. B. (2011). Tree nut phytochemicals: composition,

antioxidant capacity, bioactivity, impact factors. A systematic review of almonds, Brazils, cashews,

hazelnuts, macadamias, pecans, pine nuts, pistachios and walnuts. Nutrition research reviews, 24(2),

244–275. https://doi.org/10.1017/S095442241100014X

 

Calamelli, E., Trozzo, A., Di Blasi, E., Serra, L., & Bottau, P. (2021). Hazelnut Allergy. Medicina (Kaunas,

Lithuania), 57(1), 67. https://doi.org/10.3390/medicina57010067

 

Ebo, D. G., Verweij, M. M., Sabato, V., Hagendorens, M. M., Bridts, C. H., & De Clerck, L. S. (2012).

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clinica Belgica, 67(5), 317–321. https://doi.org/10.2143/ACB.67.5.2062683

 

Casas-Agustench, P., Salas-Huetos, A., & Salas-Salvadó, J. (2011). Mediterranean nuts: origins, ancient

medicinal benefits and symbolism. Public health nutrition, 14(12A), 2296–2301.

https://doi.org/10.1017/S1368980011002540

 

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neuroprotection in Alzheimer's disease: A neuropharmacological review of their bioactive

constituents. Pharmacological research, 129, 115–127. https://doi.org/10.1016/j.phrs.2017.12.003

 

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