Soy nuts: a dense protein snack tested only in small, short trials

The firmest fact about soy nuts is about a worry. Across 40 randomized trials in 3285 postmenopausal women, soy isoflavones at a median 75 mg a day for 24 weeks had no statistically significant effect on the womb lining, FSH or estradiol, and those trials gave isoflavones as supplements as well as foods. As food, soy nuts are protein. The US dietary survey lists 38.55 g per 3.5 oz (100 g), a single value with no spread, so a 28 g snack bag works out at about 10.8 g, recalculated from 100 g. The heart findings come from small trials. In a crossover trial of 60 postmenopausal women over 8 weeks, soy nuts in place of other protein lowered systolic blood pressure by 9.9% in hypertensive women and 5.2% in normotensive women, at one center and without blinding. In 23 healthy adults aged 60 to 70, 67 g a day for 16 weeks raised flow-mediated dilation by 1.48 percentage points (95% CI 0.08 to 2.89), a lower bound close to zero.

As people eat it, per 3.5 oz (100 g)

How much is actually in it

• Soy nuts contain 38.55 g of protein per 3.5 oz (100 g) in the US dietary survey database. — — Evidence E source
  Protein 38.55 g/100 g

What a real portion looks like

• A small single-serving bag of soy nuts is 28 g and gives about 10.8 g of protein, and a cup of 3.4 oz (95 g) gives about 36.6 g. — — Evidence E source
  28 g bag = 10.8 g protein; 1 cup 95 g = 36.6 g protein (recalculated from 100 g)

What your body absorbs

• Isoflavones from soy nuts are absorbed: after 16 weeks of 67 g a day, serum daidzein was 127.8 ng/mL and genistein 454.2 ng/mL higher than in the no-nut period. — 23 healthy adults aged 60-70; 67 g/day soy nuts (25.5 g protein, 174 mg isoflavones), 16 weeks (n = 23) Evidence B source
  Serum daidzein +127.8 ng/mL (95% CI 74.3-181.3); genistein +454.2 ng/mL (95% CI 266.6-641.8)
• Only 58% of postmenopausal women in a soy-nut trial produced equol, and the drops in diastolic blood pressure and CRP on soy nuts were seen mainly in equol producers. — 60 postmenopausal women, one-half cup of unsalted soy nuts daily, 8 weeks (n = 60) Evidence B source
  Equol producers 35/60 (58%); in women with MetS, producers DBP -7.7%, CRP -21.4%; nonproducers no significant change

What cooking and storage change

• The soy nuts used in the Boston trial were dry-roasted whole soybeans: one-half cup gave 25 g of soy protein and 101 mg of aglycone isoflavones. — 60 postmenopausal women, prepackaged daily allowance split into 3-4 portions (n = 60) Evidence B source
  One-half cup dry-roasted soy nuts = 25 g soy protein, 101 mg aglycone isoflavones

What it does to your health

• A meta-analysis of 20 studies of tree nuts, peanuts and soy nuts found no significant effect on C-reactive protein (WMD 0.17 mg/L). — 20 prospective studies/RCTs of tree nut, peanut and soy nut consumption (n = 20 studies) Evidence A source
  CRP WMD 0.17 mg/L (95% CI -0.67 to 0.33), not significant; leptin -0.71 mg/dL
• A 2025 meta-analysis of 133 RCTs found that soy foods improved flow-mediated dilation by 1.58 percentage points, with moderate-to-low certainty. — adults in RCTs of whole foods or diets lasting at least 28 days (n = 133 studies) Evidence A source
  Soy FMD MD 1.58% (95% CI 0.32-2.83)
• In 70 adults with type 2 diabetes, 2.1 oz (60 g) of soy nuts a day for 8 weeks lowered fasting glucose, total and LDL cholesterol but did not change blood pressure. — 70 patients with type 2 diabetes (35 intervention, 35 control), 8 weeks (n = 70) Evidence B source
  Fasting glucose P = 0.03, LDL-C P = 0.01; no effect on BP, HDL-C, TG

Safety, limits and interactions

• In a 16-week trial of 2.4 oz (67 g) of soy nuts a day in adults aged 60-70, no serious adverse events were reported and body weight stayed stable. — 23 healthy adults aged 60-70, 16 weeks (n = 23) Evidence B source
  No serious adverse events; body weight stable
• A meta-analysis of 40 RCTs in 3285 postmenopausal women found that soy isoflavones (median 75 mg a day for 24 weeks) had no estrogenic effect on endometrial thickness, vaginal cells, FSH or estradiol. — postmenopausal women in 40 RCTs (52 comparisons), trials of at least 3 months (n = 3285) Evidence A source
  Endometrial thickness MD -0.22 mm (95% CI -0.45 to 0.01); estradiol 1.61 pmol/L (95% CI -1.17 to 4.38); all non-significant
• Soybeans are one of the major food allergens under US law, so soy nuts must carry a soy allergen declaration. — — Evidence E source
  Soybeans listed among major food allergens

What people believe that the data does not support

• US law still allows a label claim that 25 g of soy protein a day in a diet low in saturated fat may reduce heart disease risk, although FDA proposed revoking it in 2017. — — Evidence E source
  Threshold 25 g soy protein per day
• The EU did not authorize the claim that soy helps keep arteries and the heart healthy. — — Evidence E source
  Status: non-authorized

Who this works differently for

• In a crossover RCT of 60 postmenopausal women, replacing 25 g of nonsoy protein with soy nuts for 8 weeks lowered systolic blood pressure by 9.9% in hypertensive women and by 5.2% in normotensive women. — 60 healthy postmenopausal women (hypertensive, prehypertensive, normotensive), TLC diet, 8 weeks per arm (n = 60) Evidence B source
  Systolic BP -9.9% (hypertensive), -5.2% (normotensive); diastolic -6.8% and -2.9%
• In the same trial, soy nuts lowered LDL cholesterol by 11% in hypertensive postmenopausal women but had no effect in normotensive women. — 60 postmenopausal women, 25 g soy protein from soy nuts daily, 8 weeks (n = 60) Evidence B source
  LDL-C -11%, apoB -8% (P = .04) in hypertensive women only
• In 23 healthy adults aged 60-70, eating 2.4 oz (67 g) of soy nuts a day for 16 weeks raised flow-mediated dilation by 1.48 percentage points and lowered LDL cholesterol by 6.6 mg/dL (0.17 mmol/L). — 23 healthy older men and women aged 60-70, BMI 20-30, 16-week crossover (n = 23) Evidence B source
  FMD +1.48 pp (95% CI 0.08-2.89); LDL-C -6.6 mg/dL (95% CI 0.77 to 12; metric: -0.17 mmol/L, 0.02 to 0.32); MAP -3 mmHg (95% CI 0-6)
• In children with acute lymphoblastic leukemia on maintenance chemotherapy, 1.1 oz (30 g) of soy nut powder a day for 12 weeks improved body weight, hemoglobin and fatigue compared with cowpea nut. — children aged about 6 with B-cell ALL, maintenance chemotherapy; 29 soy vs 27 cowpea completers, 12 weeks (n = 56) Evidence B source
  Weight, BMI, RBC, hemoglobin, hematocrit and fatigue improved vs cowpea (P < 0.05)

What is still unknown

• A meta-analysis of 21 RCTs found that nuts overall lowered systolic blood pressure by 1.29 mmHg only in people without type 2 diabetes, and among nut types only pistachios clearly lowered it. — adults 18+ in 21 RCTs of tree nuts, peanuts and soy nuts, >=2 weeks (n = 21 RCTs) Evidence A source
  SBP MD -1.29 mmHg (95% CI -2.35 to -0.22) in non-diabetic participants; not significant for other nut types incl. soy nuts

The bottom line

Meta-analyses that pool nuts say less for soy nuts specifically. In 21 trials of nuts and blood pressure, pistachios lowered systolic pressure clearly and the other nut types, soy nuts included, did not reach significance. Across 20 studies of tree nuts, peanuts and soy nuts, C-reactive protein did not change significantly (0.17 mg/L, 95% CI -0.67 to 0.33). A 2025 meta-analysis of 133 trials found soy foods raised flow-mediated dilation by 1.58 percentage points (95% CI 0.32 to 2.83), for soy as a food group with moderate to low certainty. In 70 adults with type 2 diabetes, 60 g a day for 8 weeks lowered fasting glucose and LDL cholesterol and left blood pressure unchanged. The abstract gives p values only, so the size of the drop is unknown. In the 60-woman trial, 58% of women produced equol, and the fall in diastolic pressure and CRP among women with metabolic syndrome showed up mainly in them. That split was made after the fact, in small groups. Children with leukemia on maintenance chemotherapy gained weight and hemoglobin on 1.1 oz (30 g) of soy nut powder a day for 12 weeks compared with cowpea, in one trial of 56 children that reports no effect sizes. It is not a basis for changing the diet of a child in cancer treatment without their care team. US law still permits a label saying 25 g of soy protein a day in a low saturated fat diet may reduce heart disease risk. The FDA proposed revoking it in 2017 and had not finalised that by September 2026. The EU did not authorize a claim that soy keeps arteries healthy, which means the evidence fell short at assessment. Soybeans are a major food allergen under US law, so soy nuts carry an allergen declaration. The 16-week trial reported no serious adverse events, with 23 people, too few to see rare harms, and it excluded anyone allergic to soy. We have no card on soy nuts and medicines or pregnancy. Every soy-nut trial here ran 8 to 16 weeks with 70 people or fewer, and none measured heart attacks or strokes.

Sources

1. soyn-daily-r5-17 · reference dataset
   FNDDS 2707433 Soy nuts: Protein 38.55 g/100 g
   USDA FNDDS 2021-2023, food code 41410010 (fdc_id 2707433) · checked 2026-09-28
2. soyn-daily-r5-18 · reference dataset
   FNDDS 2707433 Soy nuts: Protein 38.55 g/100 g, 1 small single serving bag 28 g 10.8 g · 1 cup 95 g 36.6 g
   USDA FNDDS 2021-2023, food code 41410010 (fdc_id 2707433), portions 64578, 10205 · checked 2026-09-28
3. soyn-daily-r5-04 · RCT, crossover
   Serum isoflavone concentrations were higher after the intervention as compared with the control period (daidzein: 127.8 ng/mL; 95% CI: 74.3-181.3 ng/mL; p < 0.001 and genistein: 454.2 ng/mL; 95% CI: 266.6-641.8 ng/mL; p < 0.001).
   Clin Nutr, 2022 · checked 2026-09-28
4. soyn-daily-r5-10 · RCT, crossover
   Thirty-five women (58%) were equol producers. ... When women with MetS were stratified by equol production status, equol producers had significant reductions in diastolic BP (7.7%; P = 0.02), TG (22.9%; P = 0.02), C-reactive protein (CRP) (21.4%; P = 0.01) and sICAM (7.3%; P = 0.03) on the soy diet compared to levels on the TLC diet whereas nonproducers did not (Figure 1 and Table 5).
   Metabolism, 2015 · checked 2026-09-28
5. soyn-daily-r5-11 · RCT, methods
   the TLC diet with prepackaged daily allowances of one-half cup of unsalted soy nuts (Genisoy, Fairfield, Calif) containing 25 g of soy protein and 101 mg of aglycone isoflavones divided into 3 or 4 portions spaced throughout the day. ... We chose a whole soy food, dry-roasted soybeans, which were administered 3 times daily to mimic Asians who consume whole soy food or fermented soy products high in aglycone isoflavones at several times throughout the day.
   Metabolism, 2015 · checked 2026-09-28
6. soyn-daily-r5-07 · systematic review and meta-analysis
   The meta-analysis indicated a nonsignificant increase in serum CRP concentrations following nut consumption (weighted mean difference [WMD] 0.17 mg/L, (95% CI -0.67 to 0.33, I 52.1%).
   Medicine (Baltimore), 2016 · checked 2026-09-28
7. soyn-daily-r5-08 · systematic review and meta-analysis
   soy (MD: 1.58%; 95% CI: 0.32%, 2.83%)
   Am J Clin Nutr, 2025 · checked 2026-09-28
8. soyn-daily-r5-09 · RCT, parallel
   Consuming 60 g soy nut for 8 weeks significantly decreased the fasting blood glucose (P = 0.03), total serum cholesterol (P < 0.01), LDL-c (P = 0.01), and E-Selectin (P < 0.01) and increased the capacity of serum total antioxidants (P < 0.01), brachial blood flow (P < 0.01) but didn't have any significant effect on systolic/diastolic blood pressure, HDL-c, and TG.
   Diabetes Metab Syndr, 2019 · checked 2026-09-28
9. soyn-daily-r5-05 · RCT, crossover
   No serious adverse events were reported and the soy nut regime was well tolerated. Body weights remained stable during the whole study.
   Clin Nutr, 2022 · checked 2026-09-28
10. soyn-daily-r5-13 · systematic review and meta-analysis
    Soy isoflavones had no statistically significant effect on any measure of estrogenicity; ET [mean difference, -0.22 mm (95% confidence interval, -0.45, 0.01 mm), PMD = 0.059], VMI [2.31 (-2.14, 6.75), PMD = 0.310], FSH [-0.02 IU/L (-2.39, 2.35 IU/L), PMD = 0.987], and estradiol [1.61 pmol/L (-1.17, 4.38 pmol/L), PMD = 0.256].
    Adv Nutr, 2025 · checked 2026-09-28
11. soyn-daily-r5-16 · FDA consumer guidance
    milk, eggs, fish, Crustacean shellfish, tree nuts, peanuts, wheat, and soybeans
    US FDA, Food Allergies: What You Need to Know, 2024 · checked 2026-09-28
12. soyn-daily-r5-14 · US health claim regulation
    (2) Diets low in saturated fat and cholesterol that include 25 grams of soy protein a day may reduce the risk of heart disease. One serving of [name of food] provides ____ grams of soy protein.
    21 CFR 101.82, Soy protein and risk of coronary heart disease · checked 2026-09-28
13. soyn-daily-r5-15 · EU health claim register
    POL-HC-7954 Soy -soy offers specific vascular benefits; '-soy helps keep the arteries healthy and helps keep a healthy heart; -soy helps protect the body tissues and cells from oxidation oxidative damage. Non-authorised
    EU Register on nutrition and health claims, claim POL-HC-7954, snapshot 2026-09-21 · checked 2026-09-28
14. soyn-daily-r5-01 · RCT, crossover
    Compared with the TLC diet alone, the TLC diet plus soy nuts lowered systolic and diastolic BP 9.9% and 6.8%, respectively, in hypertensive women (systolic BP> or =140 mm Hg) and 5.2% and 2.9%, respectively, in normotensive women (systolic BP<120 mm Hg).
    Arch Intern Med, 2007 · checked 2026-09-28
15. soyn-daily-r5-02 · RCT, crossover
    Soy nut supplementation lowered low-density lipoprotein cholesterol and apolipoprotein B levels 11% and 8% (P = .04 for both), respectively, in hypertensive women but had no effect in normotensive women.
    Arch Intern Med, 2007 · checked 2026-09-28
16. soyn-daily-r5-03 · RCT, crossover
    Brachial artery flow-mediated vasodilation was 1.48 percent points (pp; 95% CI: 0.08-2.89 pp; p = 0.040) higher following soy nut intake. ... Serum LDL-cholesterol was lower (0.17 mmol/L; 95% CI: 0.02-0.32 mmol/L; p = 0.027), while HDL-cholesterol and triacylglycerol concentrations were comparable.
    Clin Nutr, 2022 · checked 2026-09-28
17. soyn-daily-r5-12 · RCT, parallel
    The total energy and protein intake, and physical activity as well as body weight, body mass index, number of red blood cells, hemoglobin and hematocrit levels, and fatigue were significantly improved in the soy nut group compared to patients who consumed cowpea nut (P < 0.05).
    Nutr Cancer, 2018 · checked 2026-09-28
18. soyn-daily-r5-06 · systematic review and meta-analysis
    Our findings suggest that nut consumption leads to a significant reduction in SBP in participants without type 2 diabetes [mean difference (MD): -1.29; 95% CI: -2.35, -0.22; P = 0.02] but not in the total population. Subgroup analyses of different nut types suggest that pistachios, but not other nuts, significantly reduce SBP (MD: -1.82; 95% CI: -2.97, -0.67; P = 0.002).
    Am J Clin Nutr, 2015 · checked 2026-09-28