NutriDex

The Supplement Research Compendium
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Hazelnut

Corylus avellana

MUFA-rich tree nut that modestly lowers LDL and total cholesterol

Moderate evidence 🥜Nuts🫀Heart & Metabolic⏳Longevity

✚ Updated · How we grade evidence

Evidence tier
Moderate
Research weight
Citations
8 verified / 8
Classification
Nuts
❝
What the evidence says. Several controlled trials; effects real but modest or context-dependent.

Nutrition per serving 1 oz (28 g, ~21 hazelnuts)

28gSERVING
  • Sugars 1.2 g4%
  • Fibre 2.7 g10%
  • Other carbs 0.8 g3%
  • Protein 4.2 g15%
  • Fat 17 g61%
  • Other 2.1 g8%
What's in one serving, by weight — average composition (USDA).
Fiber10%Protein8%Vitamin E28%Magnesium11%Copper53%Manganese75%Zinc6%Selenium1%
One serving as % of the adult daily requirement (FDA Daily Values). The bold outer ring = 100% of a day's needs.
176 kcal4.2 g protein2.7 g fiber17 g fat
NutrientPer serving% daily value
Fiber2.7 g10%
Protein4.2 g8%
Vitamin E4.2 mg28%
Magnesium46 mg11%
Copper0.48 mg53%
Manganese1.7 mg75%
Zinc0.69 mg6%
Selenium0.67 µg1%
Phosphorus81 mg6%
Potassium190 mg4%
Iron1.3 mg7%
Calcium32 mg2%
Folate32 µg8%

Composition data: USDA FoodData Central ↗

What is Hazelnut?

Hazelnut (Corylus avellana) is a nut or seed used for lowers ldl ('bad') and total cholesterol in controlled feeding trials. NutriDex grades the human evidence as Moderate. Hazelnuts have moderate, mostly lipid-focused human evidence. A 2016 Bayesian meta-analysis (Perna et al., Nutrients) pooling nine controlled studies (~425 participants, 29-69 g/day for 4-12 weeks) found hazelnut-enriched diets significantly lowered LDL and total cholesterol, with HDL and triglycerides essentially unchanged and no effect on body weight or BMI - reassuring given their calorie density. Direct trial data on hard outcomes (heart attacks, diabetes, death) are limited; most cardiovascular evidence comes from nuts as a group. In the PREDIMED randomized trial (NEJM 2018), a Mediterranean diet supplemented with mixed nuts (walnuts, almonds and hazelnuts) reduced major cardiovascular events versus a control diet. Large prospective cohorts (Aune et al., BMC Medicine 2016) link higher nut intake to lower cardiovascular and all-cause mortality, but these are observational and not hazelnut-specific. Bottom line: good RCT support for cholesterol-lowering; benefits on weight, glycemia, and mortality are inferred largely from broader nut research rather than hazelnut trials.

Purported Benefits

✓Lowers LDL ('bad') and total cholesterol in controlled feeding trials
✓Leaves HDL cholesterol and triglycerides largely unchanged
✓Does not cause weight gain when substituted into the diet, despite calorie density
✓Part of nut-supplemented Mediterranean diets shown to cut major cardiovascular events
✓Higher overall nut intake is linked to lower cardiovascular and all-cause mortality in cohorts
✓Supplies heart-favorable monounsaturated fat, fiber, vitamin E, and magnesium

Dosing & Compounds

Typical Dose
About 1 oz (28-30 g) per day, a small handful (~20 nuts); trials used 29-69 g/day
Active Compounds
Monounsaturated fatty acids (oleic acid)Polyunsaturated fatty acids (linoleic acid)Dietary fiberVitamin E (alpha-tocopherol)MagnesiumPhytosterolsL-argininePolyphenols (in the skin)Folate

Safety & Cautions

Hazelnuts are a tree nut and a common cause of food allergy; in sensitized people they can trigger anaphylaxis, a medical emergency - anyone with tree-nut or peanut allergy should avoid them. They are calorie-dense (~180 kcal per 28 g), so portion control matters and they are best substituted for less healthy foods rather than simply added. Whole nuts are a choking hazard for young children; use nut butter or finely ground forms for toddlers. Most cardiovascular and mortality data come from nuts as a group, not hazelnuts specifically, so individual benefit estimates carry uncertainty. Note: unlike Brazil nuts (selenium toxicity, limit to 1-3/day) hazelnuts pose no selenium risk, and unlike peanuts (a legume prone to aflatoxin) hazelnuts are a true tree nut. Educational only — always check with your doctor or pharmacist before combining Hazelnut with any medicine.

Key Studies

meta-analysis Liu et al. 2025 ✓ PubMed
Dose-response meta-analysis of prospective cohorts reported higher nut intake associated with lower risk of CHD (20%), stroke (9%), CVD (14%), CVD mortality (26%) and all-cause mortality (23%).
Meta-analysis Perna et al. 2016 (Bayesian meta-analysis) ✓ PubMed
Across nine controlled studies (~425 participants, 29-69 g/day), hazelnut-enriched diets significantly reduced LDL and total cholesterol with no change in HDL, triglycerides, or body weight/BMI.
Meta-analysis Aune et al. 2016 (dose-response meta-analysis) ✓ PubMed
In pooled prospective cohorts, higher nut intake (~28 g/day) was associated with lower risk of cardiovascular disease, coronary heart disease, and all-cause mortality.
meta-analysis Perna et al. 2016 ✓ Full text
Bayesian meta-analysis of RCTs (9 studies, 425 participants; ~39 g/day, ~75 days) found a hazelnut-enriched diet significantly lowered LDL-C (pooled MD -0.150 mmol/L; 95%HPD -0.308 to -0.003) with a trend for lower total cholesterol and no change in HDL, triglycerides or BMI.
meta-analysis Viguiliouk et al. 2014 ✓ Full text
Meta-analysis of 12 RCTs (450 diabetics): tree nuts (median 56 g/day, includes hazelnuts) significantly lowered HbA1c by 0.07% and fasting glucose by 0.15 mmol/L vs isocaloric control diets.
RCT Estruch et al. (PREDIMED) 2018 ✓ PubMed
A Mediterranean diet supplemented with mixed nuts (walnuts, almonds, hazelnuts) reduced the incidence of major cardiovascular events versus a reduced-fat control diet in people at high cardiovascular risk.
RCT Di Renzo et al. 2019 ✓ Full text
In hypercholesterolemic adults, a hazelnut-enriched diet modulated oxidative-stress and inflammation gene expression and improved cardiovascular biomarkers without causing weight gain despite the added calories.
RCT Orem et al. 2013 ✓ PubMed
Crossover RCT in 21 hypercholesterolemic adults: 4 weeks of hazelnuts (18-20% of energy) improved endothelial function (flow-mediated dilation) and reduced LDL oxidation and inflammatory markers beyond the lipid-lowering effect.
8 sources cited · 8 verified Search all studies on PubMed ↗

Common questions about Hazelnut

What is Hazelnut used for?

Hazelnut is most often taken for Lowers LDL ('bad') and total cholesterol in controlled feeding trials, Leaves HDL cholesterol and triglycerides largely unchanged, Does not cause weight gain when substituted into the diet, despite calorie density, Part of nut-supplemented Mediterranean diets shown to cut major cardiovascular events. MUFA-rich tree nut that modestly lowers LDL and total cholesterol

Does Hazelnut work — what does the evidence say?

Moderate evidence. Several controlled trials; effects real but modest or context-dependent. Hazelnuts have moderate, mostly lipid-focused human evidence. A 2016 Bayesian meta-analysis (Perna et al., Nutrients) pooling nine controlled studies (~425 participants, 29-69 g/day for 4-12 weeks) found hazelnut-enriched diets significantly lowered LDL and total cholesterol, with HDL and triglycerides essentially unchanged and no effect on body weight or BMI - reassuring given their calorie density. Direct trial data on hard outcomes (heart attacks, diabetes, death) are limited; most cardiovascular evidence comes from nuts as a group. In the PREDIMED randomized trial (NEJM 2018), a Mediterranean diet supplemented with mixed nuts (walnuts, almonds and hazelnuts) reduced major cardiovascular events versus a control diet. Large prospective cohorts (Aune et al., BMC Medicine 2016) link higher nut intake to lower cardiovascular and all-cause mortality, but these are observational and not hazelnut-specific. Bottom line: good RCT support for cholesterol-lowering; benefits on weight, glycemia, and mortality are inferred largely from broader nut research rather than hazelnut trials.

What is the typical dose of Hazelnut?

About 1 oz (28-30 g) per day, a small handful (~20 nuts); trials used 29-69 g/day

Is Hazelnut safe? Any cautions or side effects?

Hazelnuts are a tree nut and a common cause of food allergy; in sensitized people they can trigger anaphylaxis, a medical emergency - anyone with tree-nut or peanut allergy should avoid them. They are calorie-dense (~180 kcal per 28 g), so portion control matters and they are best substituted for less healthy foods rather than simply added. Whole nuts are a choking hazard for young children; use nut butter or finely ground forms for toddlers. Most cardiovascular and mortality data come from nuts as a group, not hazelnuts specifically, so individual benefit estimates carry uncertainty. Note: unlike Brazil nuts (selenium toxicity, limit to 1-3/day) hazelnuts pose no selenium risk, and unlike peanuts (a legume prone to aflatoxin) hazelnuts are a true tree nut.

How many studies support Hazelnut?

NutriDex cites 8 sources for Hazelnut, graded "Moderate".

Cite this page
APA

Peh, D. (2026). Hazelnut (Corylus avellana): Benefits, Dosage, Side Effects & Evidence. NutriDex — The Supplement Research Compendium. Retrieved 26 Jun 2026, from https://nutridex.info/s/hazelnut

BibTeX
@misc{nutridex_hazelnut,
  author       = {Peh, Daryl},
  title        = {Hazelnut (Corylus avellana): Benefits, Dosage, Side Effects \& Evidence},
  year         = {2026},
  howpublished = {NutriDex --- The Supplement Research Compendium},
  url          = {https://nutridex.info/s/hazelnut},
  note         = {Reviewed by Dr Daryl Peh, MBBS Singapore, MMed FM. Accessed 2026-06-26}
}

For medical claims, citing the underlying primary studies linked above is preferred. NutriDex is an educational reference, not medical advice.

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