What the evidence says. Several controlled trials; effects real but modest or context-dependent.
Nutrition per serving 1 oz (28 g, ~21 hazelnuts)
Sugars1.2 g4%
Fibre2.7 g10%
Other carbs0.8 g3%
Protein4.2 g15%
Fat17 g61%
Other2.1 g8%
What's in one serving, by weight — average composition (USDA).One serving as % of the adult daily requirement (FDA Daily Values). The bold outer ring = 100% of a day's needs.
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.
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 11 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 16 Sept 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 2026-09-16}
}
For medical claims, citing the underlying primary studies linked above is preferred. NutriDex is an educational reference, not medical advice.