Hazelnuts, body fat and antioxidant genes in a small trial
What it found
In 24 healthy adults, eating 40 g of hazelnuts daily for six weeks did not change body fat or weight, but it did turn up the activity of several genes involved in antioxidant and inflammation pathways.
What they found
Studies in people
Weight and body fat
Body weight, BMI, total body fat, android and gynoid fat, and lean mass did not change significantly after six weeks. Abdominal circumference dropped slightly.
Cholesterol changes
Total cholesterol fell by about 10% and LDL cholesterol by about 12%. The ratio of total cholesterol to HDL cholesterol also improved.
Antioxidant gene activity
The activity of SOD1 and CAT, two genes for antioxidant enzymes, rose after the hazelnut diet. MIF, PPAR gamma, VDR, MTHFR, and ACE gene activity also increased.
Genes with no change
The activity of APOE, IL6R, NFKB1, IGF2R, and USF1 did not change significantly.
Blood pressure
Systolic and diastolic blood pressure did not change significantly, even though ACE gene activity went up.
What the authors conclude
“According to emerging evidences, hazelnut consumption does not lead to weight gain probably due to the improvement of the body's antioxidant capacity by the upregulation of genes implied in oxidant reactions and inflammation.”
Also in their conclusions
- They say that eating a small amount of hazelnuts regularly could be a nutritional approach for chronic diseases linked to oxidative stress and inflammation.
- They note that the lack of weight or fat gain, despite hazelnuts being high in calories, supports including them in weight loss diets.
- They call for their results to be confirmed in a larger group of people over a longer time.
How it was done
The authors wanted to see how a daily serving of hazelnuts affects body composition and the activity of genes linked to oxidative stress and inflammation, since nuts are calorie-rich but have been linked to weight maintenance.
They ran a six-week trial in 24 healthy volunteers who ate 40 g of hazelnuts (261.99 kcal) every day as a snack. Body measurements and blood samples for gene activity were taken before and after.
What it can’t tell you
- This was a small pilot study with 24 people, so the results may not apply to everyone.
- The study did not measure actual antioxidant or inflammation markers in the blood, only gene activity.
- It cannot show whether the gene changes lead to better health outcomes.
Who paid
- Authors work at
- University of Rome Tor Vergata, Italy; University of Magna Græcia, Italy; University of Vienna, Austria
The paper
- Title
- A Hazelnut-Enriched Diet Modulates Oxidative Stress and Inflammation Gene Expression without Weight Gain
- Type
- Study
- Evidence
- Studies in people
- Summarised from
- Full text
- Cite
- Di Renzo L, Cioccoloni G, Bernardini S, et al (2019). A Hazelnut-Enriched Diet Modulates Oxidative Stress and Inflammation Gene Expression without Weight Gain. Oxidative medicine and cellular longevity. doi:10.1155/2019/4683723Free full textPubMed 31354906DOI
Summary written 26 Sep 2026. Check it against the paper before it changes what you eat. How we summarise papers · Report an error