Silk Unsweetened: what a swap from cow milk to soy drink can do

Swapping 17 fl oz (500 mL) a day of cow milk for soy drink may lower LDL cholesterol by about 18 mg/dL (95% CI -33 to -3.9; metric: 0.47 mmol/L, -0.85 to -0.10), according to a network meta-analysis of 14 randomized trials with 543 people, and its authors rate that estimate as low certainty. None of those trials tested this brand, and the soy drinks in them were not necessarily unsweetened. An older review of 8 trials with 263 people found the lipid effect of soy milk limited and inconsistent, with 3 of the 8 showing no significant change in any blood lipid. The network meta-analysis also put the systolic blood pressure drop at about 8 mmHg (95% CI -10.90 to -5.55). The authors again rate that estimate as low certainty, and 8 mmHg is a large drop to expect from swapping one drink. The nutrient panel is steadier ground. USDA lists 100 g with 1.23 mcg of vitamin B12, 51 percent of the Daily Value, and 123 mg of calcium. That comes from a single record frozen in 2018, so the product on sale now may differ.

How much is actually in it

• An audit of 129 plant-based milks in Australian shops found 80.6% fortified with calcium but only 27.1% with vitamin B12 and 3.1% with iodine, and soy milk was the one type with protein similar to cow milk. — 129 plant-based milk products on sale in Illawarra supermarkets, Australia (n = 129 products) Evidence C source
  Calcium fortification 80.6%, B12 27.1%, iodine 3.1%; no significant protein difference soy milk vs cow milk
• USDA lists 100 g of this unsweetened soy beverage with 1.23 mcg vitamin B12 (51% DV), 0.21 mg riboflavin (16% DV) and 123 mg calcium (9% DV), all from fortification, with one record and no sample spread. — USDA FoodData Central SR Legacy record FDC 175223, SILK Unsweetened, soymilk Evidence E source
  Per 100 g: vitamin B12 1.23 mcg, riboflavin 0.21 mg, calcium 123 mg; Foundation samples 0; CoFID match none

What your body absorbs

• In a randomized crossover test in 12 osteopenic postmenopausal women, calcium from calcium-fortified soymilk was absorbed at a comparable hourly rate to calcium from cow milk (0.65 vs 0.66). — 12 osteopenic postmenopausal women in Australia, mean age 56.7 years, single acute dose of 1.4 tbsp (20 mL) test milk (n = 12) Evidence B source
  Hourly fractional calcium absorption alpha 0.65 +/- 0.19 for fortified soymilk vs 0.66 +/- 0.22 for cow milk, p>0.05
• In an 8-week randomized trial in 60 premenopausal women, plain soymilk raised urinary isoflavones about as much as a fermented probiotic soymilk did, with no significant difference between the two. — 60 healthy premenopausal Japanese women, soymilk or fermented soymilk twice a day for 8 weeks (n = 60) Evidence B source
  Urinary isoflavones rose significantly in both groups versus pre-intake; no between-group difference

What cooking and storage change

• A review of processing studies says the antioxidants in plant-based milks can be lost during production through heat, oxidation or leaching into processing water. — laboratory and processing studies of plant-based milk production steps Evidence D source
  Direction only: losses possible at germination, roasting, soaking, blanching, grinding, filtration and heat treatment

What it does to your health

• A network meta-analysis of 14 randomized trials (543 people) found that replacing 17 fl oz (500 mL) a day of cow milk with soy drink may lower LDL cholesterol by about 18 mg/dL (0.47 mmol/L), with low certainty. — 14 RCTs of at least 3 weeks comparing soy, rice and oat drinks with each other or with cow milk (n = 543) Evidence A source
  LDL MD -18 mg/dL (95% CI -33 to -3.9; metric: -0.47 mmol/L, -0.85 to -0.10), low certainty; HDL MD 0.39 mg/dL (-1.2 to 1.9; metric: 0.01 mmol/L, -0.03 to 0.05), moderate certainty
• In the same network meta-analysis, swapping 17 fl oz (500 mL) a day of cow milk for soy drink was linked to about 8 mmHg lower systolic blood pressure, rated low certainty. — RCTs of at least 3 weeks in the 14-trial network, soy drink versus cow milk (n = 543) Evidence A source
  Systolic MD -8.23 mmHg (95% CI -10.90 to -5.55); diastolic MD -7.82 mmHg (-13.61 to -2.02); low certainty
• A systematic review of 8 randomized trials with 263 people found the lipid-lowering effect of soy milk limited and inconsistent: 3 trials saw no change in any blood lipid. — 8 RCTs of soy milk and serum lipids published up to May 2018 (n = 263) Evidence A source
  3 of 8 trials null on all lipids; LDL fell in 3 trials, total cholesterol in 1, triglycerides in 1, HDL rose in 1

Safety, limits and interactions

• A case report describes a 70-year-old man stable on warfarin whose INR fell below range after he started soy milk and recovered within 2 weeks of stopping it. — one 70-year-old man on long-term warfarin (n = 1) Evidence D source
  Subtherapeutic INR during soy milk intake, back in range within 2 weeks after stopping
• A 2026 case report describes a woman with birch-pollen type soy allergy (Gly m 4) whose lip swelling from soy milk escalated to anaphylaxis to undercooked soy sprouts after she started the acid blocker vonoprazan. — one 59-year-old woman with pollen-food allergy syndrome, Japan (n = 1) Evidence D source
  Mild oral symptoms after soy milk; two anaphylaxis episodes to undercooked soybean sprouts during vonoprazan therapy; none in 6 months after stopping it

Who this works differently for

• Observational data link plant-based milk in children with lower BMI, height and vitamin D than cow milk, and in adolescent girls soy milk was not associated with BMI. — 6 studies in children aged 1 to 18 years: 3 cross-sectional, 1 cohort, 2 clinical trials (n = 15815) Evidence C source
  Lower BMI, height and serum vitamin D with plant-based milk vs cow milk (observational); no association of soy milk with BMI in adolescent girls
• A systematic review of 74 studies found that giving soy milk to infants at high or normal allergy risk did not prevent food allergy. — 74 studies of food allergy prevention in children and adults, searched to September 2012 (n = 74 studies) Evidence C source
  No preventive benefit of soy milk for infants at high or normal risk
• In 2025 the American Heart Association, American Academy of Pediatrics, Academy of Nutrition and Dietetics and pediatric dentists advised that children aged 5 to 18 limit plant-based milk alternatives. — children and adolescents aged 5-18, US Evidence E source
  Plant-based milk alternatives and flavored milks: limit; plain water and plain pasteurized milk as main drinks

What is still unknown

• In five-year-olds each daily cup of plant-based drink was associated with about 0.08 in (0.2 cm) less height and 0.22 lb (0.1 kg) less weight, and no randomized trial has compared these drinks with cow milk in children. — children and adolescents in cross-sectional and cohort studies found by a structured literature search Evidence C source
  Height-for-age z -0.04 (-0.07 to -0.01) and BMI-for-age z -0.06 (-0.09 to -0.03) per cup

The bottom line

Calcium from fortified soymilk seems to be absorbed about as well as calcium from cow milk. In a randomized crossover test in 12 postmenopausal women with low bone density, the hourly absorption rate was 0.65 for fortified soymilk and 0.66 for cow milk. That was a single dose with one proprietary calcium phosphate fortificant, so another brand's calcium salt may behave differently. In a pilot trial in 60 healthy premenopausal Japanese women, plain soymilk twice a day for 8 weeks raised urinary isoflavones about as much as a fermented soymilk did. An audit of 129 plant milks on Australian shelves found soy milk the one type whose protein did not differ significantly from cow milk. In that audit 80.6 percent of the drinks had added calcium, only 27.1 percent added vitamin B12 and 3.1 percent added iodine, so the label is worth reading for all three. A processing review says antioxidants in plant milks can be lost to heat, oxidation or leaching during production, with no numbers and nothing specific to soy. Who should be careful. A case report describes a 70-year-old man stable on warfarin whose INR fell below range after he started drinking soy milk and came back within 2 weeks of stopping it. It is one case with a speculative mechanism, and anyone on warfarin who changes their milk should tell whoever checks their INR. Another single case, from Japan, describes a 59-year-old woman with birch-pollen type soy allergy who had mild lip swelling from soy milk. She later had two episodes of anaphylaxis to undercooked soy sprouts while taking the acid blocker vonoprazan. For children, the 2025 advice from the American Heart Association, the American Academy of Pediatrics, the Academy of Nutrition and Dietetics and pediatric dentists is that ages 5 to 18 should limit plant-based milk alternatives. It does not single out fortified soy drinks. Observational studies link plant-based milk with lower BMI, height and vitamin D in children than cow milk, mostly from cross-sectional data that did not separate soy from other drinks. In five-year-olds each daily cup of plant-based drink was associated with about 0.08 in (0.2 cm) less height and 0.22 lb (0.1 kg) less weight. The same review found no randomized trial comparing these drinks with cow milk in children. A review of 74 studies found that giving soy milk to infants at high or normal allergy risk did not prevent food allergy, and the infant soy feeding in those studies was mostly soy formula.

Sources

1. slku-06 · cross-sectional audit
   Of these, 80.6% were fortified with calcium; however, fortification with other micronutrients was less common, ranging from 27.1% being fortified with vitamin B12 and 3.1% being fortified with iodine...However, there was no significant difference in protein content between soy milk and cow's milk.
   Nutr Diet, 2025 · checked 2026-09-28
2. slku-13 · USDA FoodData Central, SR Legacy dataset
   SILK Unsweetened, soymilk (FDC 175223, SR Legacy, Legumes and Legume Products): vitamin B12 1.23 ug per 100 g = 51% DV; riboflavin 0.21 mg = 16% DV; calcium 123 mg = 9% DV; Foundation samples 0, CoFID match none
   USDA FoodData Central, SR Legacy, 2018, FDC 175223 · checked 2026-09-28
3. slku-04 · randomized crossover trial
   The mean hourly fractional calcium absorption from fortified soymilk was found to be comparable to that of cows' milk: alpha = 0.65+/-0.19 and alpha =0.66+/-0.22, p>0.05, respectively.
   Asia Pac J Clin Nutr, 2010 · checked 2026-09-28
4. slku-05 · randomized trial
   Both the FSM and SM groups had improved skin condition as assessed from scores of overall satisfaction, dryness, moisture, elasticity, coarseness, pigmentation and/or stratum corneum morphology, as well as significantly increased levels of urinary isoflavones during the intake period compared with the pre-intake period, although there were no significant differences between the two groups.
   Benef Microbes, 2018 · checked 2026-09-28
5. slku-12 · review
   Presumably, antioxidants in PBM could be potentially lost due to thermal degradation, oxidation or leaching into processing water.
   Crit Rev Food Sci Nutr, 2024 · checked 2026-09-28
6. slku-01 · network meta-analysis
   Fourteen RCTs involving 543 participants were included, comparing soy-, rice-, oat drinks, and cow milk...Replacing 500 mL/d of cow's milk with soy drink may reduce low-density lipoprotein (LDL) cholesterol [MD: -0.47 mmol/L (-0.85; -0.10); low certainty], but showed no effect for high-density lipoprotein (HDL) cholesterol [MD: 0.01 mmol/L (-0.03; 0.05); moderate certainty].
   Adv Nutr, 2026 · checked 2026-09-28
7. slku-02 · network meta-analysis
   Replacing 500 mL/d of cow milk with soy drink may reduce systolic and diastolic blood pressure [MD: -8.23 mmHg (-10.90; -5.55); MD: -7.82 mmHg (-13.61; -2.02); low certainty].
   Adv Nutr, 2026 · checked 2026-09-28
8. slku-03 · systematic review
   Eight eligible trials comprising a total of 263 subjects were included in this review. Three studies reported no significant improvement in any of the serum lipid parameters following soy milk consumption.
   Complement Ther Med, 2019 · checked 2026-09-28
9. slku-10 · case report
   A 70-year-old white man who was stable on warfarin therapy developed subtherapeutic INR values after ingesting soy protein in the form of soy milk...INR values returned to therapeutic concentrations within 2 weeks after discontinuation of the soy milk.
   Ann Pharmacother, 2002 · checked 2026-09-28
10. slku-11 · case report
    A 59-year-old woman had experienced mild oral allergy syndrome-like symptoms, including lip swelling, after soy milk ingestion, while tolerating other soybean products...Because vonoprazan was the only new factor common to both episodes, it was considered a possible cofactor.
    Front Allergy, 2026 · checked 2026-09-28
11. slku-07 · systematic review
    Observational studies found that consumption of plant-based milk was associated with lower childhood body mass index (BMI), height, and serum vitamin D concentrations compared with cow milk. No association was found between soy milk consumption and BMI in adolescent girls.
    J Nutr, 2024 · checked 2026-09-28
12. slku-09 · systematic review
    Soy milk and delaying the introduction of solid foods beyond 4 months did not have preventive benefits in those at high or normal risk.
    Allergy, 2014 · checked 2026-09-28
13. slku-14 · expert body position
    Other beverages like plant-based milk alternatives and flavored milks should be limited, while sugar-sweetened beverages, beverages with non-sugar sweeteners, and beverages with caffeine or other stimulants should be avoided.
    American Heart Association newsroom, Top Health Experts Release New Drink Recommendations for Kids and Teens' Overall Health, 29 Jan 2025 · checked 2026-09-29
14. slku-08 · review
    The height-for-age z-score was -0.04 [-0.07; -0.01] and the BMI-for-age z-score was -0.06 [-0.09; -0.03] for each cup of PBMA in five-year-olds, corresponding to reductions of 0.2 cm in height and 0.1 kg in weight...Our search did not retrieve any longitudinal studies on long-term outcomes or any randomized intervention trials comparing the consumption of cow's milk and PBMA.
    Dtsch Arztebl Int, 2026 · checked 2026-09-28