III. Nuts and seeds

III. 13 Cashew

The Amazon's magical "apple" – high magnesium, MUFA-dominant fat profile, and creamy texture for plant pastes.

Latin: Anacardium occidentale L. (Anacardiaceae)

" evidence="★ ★ (human interventions – lipid profile; moderate mechanistic argument)" microbiota="MUFA + fiber + polyphenol; fructan prebiotic in small amounts"]

Cashew in 1 minute

What does it provide? High monounsaturated fat (MUFA – oleic acid, ≈ 24 g/100 g, about 60% of total fat), magnesium (≈ 292 mg/100 g – one of the highest sources), zinc (≈ 5.8 mg/100 g), iron (≈ 6.7 mg/100 g), and plant sterols (β-sitosterol, campesterol – cholesterol absorption reduction) [2801]. It also contains small amounts of anacardic acid (concentrated in the shell – commercial "raw" cashew is all heat-treated, since the raw shell is allergenic and irritating).

How much? A handful per day (≈ 28 g, about 15–18 pieces) – in RCTs, 28–64 g cashew/day over 4–12 weeks reduced LDL cholesterol and improved HDL/LDL ratio (Mah 2017 Am J Clin Nutr [2797]; Mohan 2018 J Nutr [2798]).

When to avoid? Tree nut allergy (anaphylaxis, cross-reaction with pistachio – Anacardiaceae family), IBS flare (high fructan FODMAP), active gallstones (fat content can provoke bile colic), aflatoxin contamination (in poor storage), kidney stones (moderate oxalate ≈ 260 mg/100 g – high), severe calorie restriction, child < 4 years (choking hazard + allergy risk), home-prepared raw cashew (shell anacardic acid irritation).

📜 Historical Overview

Cashew originates from the Amazon-Brazil homeland, where the indigenous Tupi people consumed the "acaju" (from which the English cashew) seed and its attached sweet-sour "cashew apple" for centuries. In the mid-16th century, Portuguese traders and colonists transported it to India (Goa) and Mozambique – both colonies adopted it perfectly. India became the world's largest cashew processor by the late 19th century, since the shell removal – which contains the corrosive anacardic acid – must be done by hand, in a labor-intensive process. By the mid-20th century, Vietnam and Côte d'Ivoire took the leading role. Cashew is botanically NOT a nut: the seed itself hangs from the "apple," and its shell is chemically related to poison ivy/oak – which is why "raw" commercial cashew is always lightly heat-treated, to inactivate the anacardic acid residue. (Britannica)

Scientific Background

Cashew's bioactive profile is primarily lipid-oriented. (1) MUFA-dominant fat profile: of the ≈ 44 g/100 g total fat, about 60% is oleic acid (the key MUFA of the Mediterranean diet), ≈ 18% PUFA (mainly linoleic acid, omega-6), and ≈ 20% SFA. Clinically, cashew intervention RCTs (Mah 2017 Am J Clin Nutr – randomized, crossover, controlled-feeding trial, NOT a meta-analysis; Mohan 2018 J Nutr – Indian type 2 diabetes RCT) showed moderate LDL reduction (≈ −3 to −6%), HDL increase, and blood pressure reduction [2797] [2798]; the effect is moderate, but comparable to other tree nuts.

(2) Magnesium and zinc: cashew is an outstanding magnesium source (≈ 292 mg/100 g) and zinc source (≈ 5.8 mg/100 g) – magnesium is critical for glucose metabolism, blood pressure regulation, muscle function, and bone mineralization. A 30 g serving covers ≈ 22% of daily Mg need.

(3) Plant sterols and polyphenols: β-sitosterol and campesterol have cholesterol-absorption-competing effect. Cashew's polyphenol content is lower than walnut's or almond's (Bolling 2011 Nutr Res Rev) [981], so tannin- and ellagitannin-mediated microbiome effects are smaller.

(4) Anacardic acid (in shell): the phenolic lipid concentrated in the raw shell, which is irritant and antimicrobial. Commercial cashew is always heat-treated or steamed, anacardic acid residue is negligible (Trox 2010 J Agric Food Chem) [2800].

From a microbiome perspective, cashew's fiber content (≈ 3.3 g/100 g, mainly insoluble + small amount of fructan) provides moderate SCFA support; in preclinical models (Mandalari 2018 Br J Nutr – in vitro prebiotic studies on almond skin) the tree-nut polyphenol matrix has shown positive microbiome diversity increase. However, high fructan triggers symptoms in IBS-sensitive individuals.

✅ Combine with

+ Cashew cream (soaked + blended cashew): creamy, vegan sauce and dessert base; soaking reduces phytate.
+ Mediterranean salad: oleic acid + olive oil + leafy greens + tomato.
+ Vitamin C (lemon juice, tomato): increases iron (non-heme) absorption.
+ Gentle toasting (150 °C, 10–12 min): flavor deepening without MUFA oxidation.
+ Legume + whole grain dinner: cashew in spicy curries (Indian korma pattern) – classic matrix.
+ Soaking 4–8 hours (cream cashew paste): smoother texture + phytate reduction.

🚫 Avoid combining with

High heat, long roasting (≥ 180 °C, 20+ minutes): MUFA oxidation.
Salted, flavored cashew + antihypertensive drug: sodium load.
Iron supplement in the same time window: phytate chelation – separate by ≥ 2 hours.

⚠️ When to avoid – condition-specific

Tree nut allergy: strict avoidance. Cross-reactivity with pistachio (shared Anacardiaceae family) – particular danger.
IBS flare: high fructan FODMAP – avoid, small portion (≤ 10 g) tolerable in reintroduction.
Active gallstones, bile duct obstruction: fat content can provoke bile colic.
Kidney stones (calcium oxalate): moderate-high oxalate content – 30 g/day safe, more is risky.
Aflatoxin-sensitive populations: discard rancid/moldy cashews – airtight packaging, refrigerated storage.
Child < 4 years: whole cashew choking hazard + high allergy risk.
Severe calorie restriction: 30 g cashew ≈ 165 kcal.

❌ Myths and their refutation

"Raw cashew is the healthiest."Myth. "Raw"-labeled commercial cashew is all lightly heat-treated (steamed or roasted), since fully raw shell-on seed contains anacardic acid residue, which is irritating. The "raw" label refers to gentle processing, not to a fully unprocessed state.

"Cashew is the cheapest nut, therefore lower quality."Mistaken. Cashew's price stems from processing complexity (manual shelling, anacardic acid elimination) – its quality indicators in terms of lipid profile, magnesium, and zinc are not determined by this.

"Cashew makes you fat."Partly myth. Cashew's 30 g daily serving is ≈ 165 kcal, MUFA-dominant. According to nut-intervention meta-analyses (Kim 2017 Nutrients), regular nut and seed consumption is NOT associated with weight gain, and even a mild BMI decrease compared to control – due to satiety and partial malabsorption.

"Cashew is a natural anti-depressant."Myth. Cashew contains tryptophan (≈ 290 mg/100 g), the serotonin precursor, BUT the relationship between dietary tryptophan intake and central nervous system serotonin level is NOT linear – blood-brain barrier passage is strictly regulated. "Cashew = SSRI-equivalent" claims are not scientifically grounded.

References

[981] Bolling BW et al. Tree nut phytochemicals: composition, antioxidant capacity, bioactivity, impact factors2011;24(2):244–275. Nutr Res Rev. Link

Tree nuts contain an array of phytochemicals including carotenoids, phenolic acids, phytosterols and polyphenolic compounds such as flavonoids, proanthocyanidins (PAC) and stilbenes, all of which are included in nutrient databases, as well as phytates, sphingolipids, alkylphenols and lignans, which are not. The phytochemical content of tree nuts can vary considerably by nut type, genotype, pre- and post-harvest conditions, as well as storage conditions. Genotype affects phenolic acids, flavonoids, stilbenes and phytosterols, but data are lacking for many other phytochemical classes. During the roasting process, tree nut isoflavones, flavanols and flavonols were found to be more resistant to heat than the anthocyanins, PAC and trans-resveratrol. The choice of solvents used for extracting polyphenols and phytosterols significantly affects their quantification, and studies validating these methods for tree nut phytochemicals are lacking. The phytochemicals found in tree nuts have been associated with antioxidant, anti-inflammatory, anti-proliferative, antiviral, chemopreventive and hypocholesterolaemic actions, all of which are known to affect the initiation and progression of several pathogenic processes.

[2797] Mah E, Schulz JA, Kaden VN, Lawless AL, Rotor J, Mantilla LB, Liska DJ. Cashew consumption reduces total and LDL cholesterol: a randomized, crossover, controlled-feeding trial. American Journal of Clinical Nutrition. 2017. Link

Randomized, crossover, controlled-feeding trial showing that cashew consumption reduces total and LDL cholesterol. It supports the modest lipid-improving, MUFA-based cardiovascular effect of cashews.

[2798] Mohan V, Gayathri R, Jaacks LM, Lakshmipriya N, Anjana RM, Spiegelman D, Jeevan RG, Balasubramaniam KK, Shobana S, Jayanthan M, Gopinath V, Divya S, Kavitha V, Vijayalakshmi P, Bai MR, Unnikrishnan R, Sudha V, Krishnaswamy K, Salas-Salvadó J, Willett WC. Cashew nut consumption increases HDL cholesterol and reduces systolic blood pressure in Asian Indians with type 2 diabetes. Journal of Nutrition. 2018. Link

Randomized trial in Asian Indians with type 2 diabetes showing that cashew consumption increased HDL cholesterol and reduced systolic blood pressure. It supports the modest cardiometabolic effect of cashews.

[2800] Trox J, Vadivel V, Vetter W, Stuetz W, Scherbaum V, Gola U, Nohr D, Biesalski HK. Bioactive compounds in cashew nut (Anacardium occidentale L.) kernels: effect of different shelling methods. Journal of Agricultural and Food Chemistry. 2010. Link

Study of bioactive compounds in cashew nut (Anacardium occidentale) kernels and the effect of different shelling methods. It supports the conclusion that anacardic-acid residue in commercial (heat-treated) cashews is negligible.

[2801] . Nuts, cashew nuts, raw. USDA FoodData Central. 2019. Link

Entry from the USDA FoodData Central nutrition database for raw cashew nuts, documenting macro- and micronutrient composition (including magnesium, zinc, MUFA). A reference source for the nutrient values reported in the chapter.

[2802] . Cashew — FODMAP serving guidance. Monash University FODMAP. 2023. Link

Classification from the Monash University FODMAP database rating cashews as high FODMAP in larger servings due to fructan content but tolerable in small servings (≤ 10 g). It provides a practical basis for IBS-friendly portioning.