Nutritionally, walnuts are unique among nuts as they are the only nuts that are rich in the essential omega-3 unsaturated fatty acid, alpha-Linolenic acid (ALA)1. They are rich in unsaturated fats, naturally low in sugar and salt and a source of dietary fibre. What’s more, a 30g daily handful of walnuts will meet 10-33% of UK Reference Nutrient Intake (RNI) values (for both adult men and women aged 19-50yrs +) for vitamins B1 (thiamine), B6 (pyridoxine), and B9 (folate), as well as minerals magnesium, phosphorus and copper.1 Click here to see walnuts’ full nutritional profile.
100g of walnuts provides 7.5g of omega-3 fatty acid, alpha-Linolenic acid (ALA), while a daily handful of 30g provides 2.24g.1 ALA is associated with the maintenance of normal cholesterol levels and improved endothelial function.2,3 Walnuts in particular have been shown to improve endothelial function, partly due to their ALA content.4,5 More than half the UK adult population is living with elevated serum cholesterol levels (>5mmol/L), mainly driven by raised low-density lipoprotein cholesterol.6 Scientific evidence has consistently demonstrated a dose-dependent relationship between serum LDL-C and the risk of cardiovascular disease.7
Almost half (47%) of walnuts’ weight is made up of polyunsaturated fats, with a 30g serving providing 14g1. This is equivalent to 100% and 78% of the UK DRV respectively, for adult women and men2. It is well established that the replacement of energy from saturated fats with polyunsaturated fats is most effective at reducing low-density lipoprotein (LDL) cholesterol levels, a primary modifiable risk factor to heart disease.8-11
Walnuts are a rich source of B vitamins B1, B6, B7 and B9, and a source of B5 (per 100g). A 30g daily serving provides 11% (0.12mg), 14% (0.2mg), 12% (6 µg), 10% (20 µg), and 8% (0.48mg) of the Nutrient Reference Values (NRVs) for these vitamins respectively.2 Walnuts also contain 1.2mg of vitamin E per 30g1 – 10% of NRV.
- Vitamin B1 (thiamin) is essential for energy production from carbohydrates and is involved with the metabolism of amino acids and fats. Thiamine is also needed for normal psychological function, heart health and the normal function of the nervous system.12
- Vitamin B6 (pyridoxine) is involved in amino acid metabolism, conversion of muscle glycogen to glucose and the production of mood hormones serotonin and norepinephrine – as well as the body’s clock adjuster, melatonin.12 Vitamin B6 also contributes to the normal function of the nervous and immune systems, in conjunction with vitamins B12 and B9. Additionally, it helps control levels of homocysteine and assists in vitamin B12 absorption, which is essential for red blood cell production.12,13
- Vitamin B7 (biotin) is needed for normal energy-yielding metabolic pathways, and therefore is required to release energy from macronutrients, such as fat, protein and carbohydrates. Biotin is also involved in the normal function of the nervous system and is needed for the normal structure and function of mucous membranes, the skin and hair.12
- Vitamin B9 (folate) is needed for normal psychological function, and therefore plays an important role in mental and emotional health. It is also needed for DNA and RNA production, and is critical during rapid growth development in infancy, adolescence and pregnancy.11,12 Vitamin B9, in conjunction with vitamin B12, is involved in the production of red blood cells and assists with reducing the occurrence of neural tube defect.12 According to the most recent national diet survey, most people are getting enough folate, although 8% of teenage girls and 4% of adult women have intakes below the Lower Reference Nutrient Intake (LRNI) - i.e. intakes that are likely to be inadequate.14 It is important to remember that during conception and pregnancy, higher doses of folate are recommended.
- Vitamin B5 (Pantothenic acid) has a central role in normal synthesis and the metabolism of steroid hormones, vitamin D and some neurotransmitters. It is also involved in several central energy-yielding metabolic pathways, and helps support normal mental performance.12
- Vitamin E contributes to the protection of cells from oxidative stress, which has the important role of maintaining membrane integrity in virtually all human cells by reducing free radical damage.1,12,15
Walnuts are rich in magnesium, phosphorus, copper and manganese, and a source of iron, zinc and potassium (per 100g). A 30g serving provides: 48mg of magnesium (13% NRV), 114mg of phosphorus (16% NRV), 0.4mg of copper (40% NRV), 1mg of manganese (50% NRV), 0.9mg iron (6% NRV), 0.8g zinc (8% NRV) and 135mg of potassium (7% NRV).1,2
- Magnesium is needed to maintain normal nerve and muscle function. In conjunction with calcium and vitamin D, it is also critical for bone strength.12,16 Additionally, magnesium plays a role in blood glucose regulation, energy production and protein and RNA synthesis.16 Magnesium intake is exceptionally low among teenagers in the UK, especially teenage girls. 27% of boys and 48% of girls aged 11-18 years are consuming less than the LRNI for magnesium.14 What’s more, 12% of adults and 15% of older adults (aged 65+) are failing to reach the LRNI.14
- Phosphorus is second only to calcium as the most abundant mineral in the body. Its key role is the maintenance of bones and teeth, which is where 85% of the body’s phosphorus is found. Additionally, phosphorus is key in energy production and the repair of all tissues and cells in the body, as well as the production of DNA and RNA.12,17
- Copper is incorporated into many metalloenzymes, which act as catalysts for numerous biological functions – including the maintenance of connective tissue, energy metabolism, and normal function of the nervous, immune and antioxidant systems. It also assists with iron transport. 1,18
- Manganese, like copper, is incorporated into many metalloenzymes which assist in the production of collagen and normal bone development, production of sex hormones, metabolism of amino acids and carbohydrates and antioxidant function.12,19
- Iron plays a critical role in multiple biological functions, including normal cognitive development – especially in neonates and young children. Iron is also important to the formation of haemoglobin for oxygen transportation, as well as the normal function of the immune system.12,15 The latest national diet survey reveals that iron intakes are critically low (below the LRNI) in 48% of teenage girls and 27% of 19-64-year-old women 14. A daily 30g serving of walnuts can add 0.9g of iron (6-10% of a woman’s DRV, or 8.7-14.8mg) to the diet.1,2
- Zinc is an essential mineral for cell division and, therefore, for growth and tissue repair and for normal fertility and reproduction.12 In addition, it protects cells from damage from oxidative stress and assists the immune system, as well as playing a critical role in skin and bone health via the production of collagen and alkaline phosphatase.12 In general, the UK population has adequate intakes of zinc. However, teenagers (especially girls) are prone to consuming excessively low levels. 17% of boys and 22% of girls aged 11-18 years have zinc intakes below the LRNI.14
- Potassium is essential for water and electrolyte balance and the normal functioning of cells, including nerves and muscles. Potassium also contributes to the maintenance of normal blood pressure,12 potentially by offsetting the impact of some of the sodium in the diet. Unfortunately, potassium intakes fall short in many population groups: 15% of teenage boys, 33% of teenage girls, 26% of 19-64-year-old women and 11% of 19-64-year-old men are consuming less than the LRNI.
|Nutritionals||% DRVs for adult men (19-50 yrs+)||% DRVs for adult women (19-50 yrs+)|
|Energy||kj||851||8% (10,467)||10% (8,374)|
|Energy||kcal||206||8% (2,500)||10% (2,000)|
|Fat||g||20.6||21% (≤97)||26% (≤78)|
|SFA||g||2.3||7% (≤ 31)||10% (≤ 24)|
|MUFA||g||3.2||9% (36)||11% (29)|
|PUFA||g||14.0||78% (18)||100% (14)|
|Omega-3 fat (ALA - alpha-Linolenic Acid)||g||2.24||NA||NA|
|Omega-6 fats (LA - Linoleic Acid)||g||11.8||NA||NA|
|Total Trans Fats||g||0||0 (<6)||0 (<4)|
|Carbohydrate||g||1||0.3% (333)||0.4% (267)|
0 (≤ 33)
0 (≤ 27g)
|Fibre (AOAC)||g||1.4||5% (≥ 30)||5% (≥ 30)|
|Protein||g||4.4||8% (56)||10% (45)|
|Salt equiv.||g||0.01||0.2% (≤6)||0.2% (≤6)|
|Vitamin E||mg||1.2||10% (NRV 12)||10% (NRV 12)|
|Thiamin (B1)||mg||0.12||12-13% (0.9 -1.0)||15% (0.8)|
|Riboflavin (B2)||mg||0.04||3% (1.3)||4% (1.1)|
|Niacin (B3)||mg||0.36||2% (16-17)||3% (12-13)|
|Pantothenic Acid (B5)||mg||0.48||8% (NRV 6)||8% (NRV 6)|
|Vitamin B6||mg||0.2||14% (1.4)||17% (1.2)|
|Folate (B9)||µg||20||10% (200)||10% (200)|
|Biotin||µg||6.0||12% (NRV 50)||12% (NRV 50)|
|Potassium||mg||135||4% (3500)||4% (3500)|
|Calcium||mg||28||4% (700)||4% (700)|
|Magnesium||mg||48||16% (300)||18% (270)|
|Phosphorus||mg||114||21% (550)||21% (550)|
|Iron||mg||0.9||10% (8.7)||6-10% (8.7-14.8)|
|Copper||mg||0.4||33% (1.2)||33% (1.2)|
|Zinc||mg||0.8||8% (9.5)||11% (7)|
|Manganese||mg||1||50% (NRV 2)||50% (NRV 2)|
|Selenium (Se)||µg||0.9||1% (75)||2% (60)|
|Iodine (I)||µg||2.7||2% (140)||2% (140)|
* DRV = Dietary Reference Value
* RNI = Reference Nutrient Intake
* NRV = Labelling Nutrient Reference Value (no UK DRV/ RNI set)
* NA = no DRV set for the UK
Department of Health (1991) Dietary Reference Values for Food Energy and Nutrients for the United Kingdom no. 41: Report of the Panel on Dietary Reference Values of the Committee on Medical Aspects of Food Policy. London: HMSO
- Dietplan7. The UK Nutrient Databank: Forestfield; 2017.
- PHE. Government Dietary Recommendations: Government recommendations for food energy and nutrients for males and females aged 1 – 18 years and 19+ years. London: PHE; 2016.
- PHE. Guidance: The Eatwell Guide. Gov.UK. March 17, 2016. Available at: https://www.gov.uk/government/publications/the-eatwell-guide. Accessed March 2017.
- EFSA. Commission Regulation (EU) No 432/2012 of 16 May 2012 establishing a list of permitted health claims made on foods, other than those referring to the reduction of disease risk and to children’s development and health;L 136:1-40.
- Ros E. Nuts and novel biomarkers of cardiovascular disease. Am J Clin Nutr. 2009;89(Suppl):1649S–56S.
- Heart UK The Cholesterol Charity https://heartuk.org.uk/press/press-kit/key-facts-figures
- Ference B, Ginsberg H, Graham I, et al. Low-density lipoproteins cause atherosclerotic cardiovascular disease. Evidence from genetic, epidemiologic, and clinical studies. A consensus statement from the European Atherosclerosis Society Consensus Panel. Eur Heart J. 2017;0:1–14.
- Astrup A, Dyerberg J, Elwood P, et al. The role of reducing intakes of saturated fat in the prevention of cardiovascular disease: where does the evidence stand in 2010. Am J Clin Nutr. 2011;93:684-688.
- Hooper L, Martin N, Abdelhamid A, et al. Reduction in saturated fat intake for cardiovascular disease (Review). Cochrane Systematic Review. June 2015:(6):CD011737.
- Briggs M, Petersen K, Kris-Etherton P. Saturated fatty acids and cardiovascular disease: replacements of saturated fat to reduce cardiovascular risk. Healthcare. June 2017;5(23):pii: E29.
- Sanders T. Reappraisal of SFA and cardiovascular risk. Proc Nutr Soc. November 2013;72(4):390-398.
- EFSA. EU Register on nutrition and health claims. European Commission Food. November 20, 2016. Available at: http://ec.europa.eu/food/safety/labelling_nutrition/claims/register/public/?event=search. Accessed July 25, 2017.
- University of Maryland Medical Centre. Vitamin B6 (Pyridoxine). University of Maryland Medical Centre. August 5, 2015. Available at: http://www.umm.edu/health/medical/altmed/supplement/vitamin-b6-pyridoxine. Accessed July 25, 2017.
- PHE, FSA, MRC. Official Statistics: NDNS results from years 5 and 6 (combined) of the rolling programme 2012-2013 & 2013-2014. Gov.UK. September 9, 2016. Available at: https://www.gov.uk/government/statistics/ndns-results-from-years-5-and-6-combined. Accessed May 2017.
- Joint FAO/WHO Expert Consultation. Vitamin and mineral requirements in human nutrition – second edition. Bhangok: WHO / FAO; 2004.
- NIH US National Library of Medicine. Magnesium in diet. Medline Plus. February 2, 2015. Available at: https://medlineplus.gov/ency/article/002423.htm. Accessed July 25, 2017.
- University of Maryland Medical Centre. Phosphorus. University of Maryland Medical Centre. August 5, 2015. Available at: http://www.umm.edu/health/medical/altmed/supplement/phosphorus. Accessed July 26, 2017.
- University of Maryland Medical Centre. Copper. University of Maryland Medical Centre. January 2, 2015. Available at: http://www.umm.edu/health/medical/altmed/supplement/copper. Accessed July 25, 2017.
- University of Maryland Medical Centre. Manganese. University of Maryland Medical Centre. May 31, 2013. Available at: http://www.umm.edu/health/medical/altmed/supplement/manganese. Accessed July 25, 2017.
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