Silk Plus Fiber: soymilk with fiber from an unnamed source

Swapping cow's milk for soymilk lowers cholesterol by a small amount. A meta-analysis of 17 randomized trials in 504 adults, lasting 3 weeks or longer, found the swap cut LDL cholesterol by 7.3 mg/dL (95% CI 3.5 to 11; metric: 0.19 mmol/L, 0.09 to 0.29) with high certainty and systolic blood pressure by 8 mmHg (95% CI 1.11 to 14.89) with moderate certainty. Those trials used ordinary soymilks, and we found no study of Silk Plus Fiber itself. The one record for it, a branded USDA entry that may be out of date, puts a 243 g cup at about 5.1 g of fiber, 6 g of protein, 299 mg of calcium and 3 ug of vitamin B12 for 100 calories. The record does not say where the fiber comes from, and we could not confirm it from a label, so this page credits the drink with no effect of any particular fiber.

How much is actually in it

• One cup (243 g) of Silk Plus Fiber soymilk carries about 5.1 g fiber, 6 g protein, 299 mg calcium and 3 ug vitamin B12 for 100 calories. — USDA SR Legacy branded record, per 3.5 oz (100 g) scaled to 1 cup (243 g) Evidence E source
  Per 100 g: 41 calories, fiber 2.1 g, protein 2.47 g, sugars 2.88 g, calcium 123 mg, B12 1.23 ug, vitamin D 1.2 ug

What your body absorbs

• In a randomized crossover test in 12 osteopenic postmenopausal women, calcium from phosphate-fortified soymilk was absorbed as well as calcium from cow's milk (hourly rate 0.65 vs 0.66). — osteopenic post-menopausal women, mean age 56.7, Australia, single test drinks (n = 12) Evidence B source
  Fractional absorption rate alpha 0.65 +/- 0.19 soymilk vs 0.66 +/- 0.22 cow's milk, p > 0.05
• In 20 young women, calcium from carbonate-fortified soymilk was absorbed like cow's milk (21.1% vs 21.7%), while tricalcium phosphate soymilk gave less (18.1%). — healthy young women, mean age 23, 250 mg calcium test loads (n = 20) Evidence C source
  Fractional Ca absorption 0.211 carbonate soymilk, 0.217 cow's milk, 0.181 tricalcium phosphate soymilk

What it does to your health

• A meta-analysis of 17 randomized trials in 504 adults found that swapping cow's milk for soymilk lowered LDL cholesterol by 7.3 mg/dL (0.19 mmol/L) and systolic pressure by 8 mmHg. — adults with a range of health statuses, trials of 3 weeks or longer (n = 504) Evidence A source
  LDL-C -7.3 mg/dL (-11 to -3.5; metric: -0.19 mmol/L, -0.29 to -0.09); non-HDL-C -10 mg/dL (-0.26 mmol/L); SBP -8.00 mmHg (-14.89 to -1.11); DBP -4.74 mmHg

Safety, limits and interactions

• A 70-year-old man stable on warfarin fell below his target INR after starting soy milk and returned to range within 2 weeks of stopping it. — one 70-year-old man on warfarin (n = 1) Evidence D source
  Subtherapeutic INR while drinking soy milk; normal within 2 weeks after stopping

What people believe that the data does not support

• US rules still allow labels to say that 25 g of soy protein a day in a low saturated fat diet may reduce heart disease risk, although FDA proposed revoking this claim in 2017. — US food labeling regulation Evidence E source
  Authorized health claim, proposed for revocation (not finalised)

Who this works differently for

• A systematic review of 6 studies in 15,815 children linked plant-based milk with lower BMI, height and vitamin D than cow's milk, while fortified soy milk was linked with higher bone density in girls with low calcium intake. — children and adolescents aged 1-18, 3 cross-sectional, 1 cohort, 2 trials (n = 15815) Evidence C source
  Direction only: lower BMI, height, serum vitamin D with plant milks; higher bone density with fortified soy milk in low-calcium girls

The bottom line

Calcium from fortified soymilk can be absorbed about as well as from cow's milk, depending on the calcium salt used. In 20 young women, soymilk fortified with calcium carbonate was absorbed at 21.1 percent against 21.7 percent for cow's milk, and soymilk with tricalcium phosphate at 18.1 percent, in single test meals. In 12 women with thinning bones after menopause, a calcium phosphate fortified soymilk matched cow's milk on hourly absorption (0.65 against 0.66), in a tiny acute test with 1.4 tbsp (20 mL) doses. Which salt this product uses is not on the record we have. US rules still let a label say that 25 g of soy protein a day, in a diet low in saturated fat and cholesterol, may reduce the risk of heart disease. FDA proposed revoking that claim in 2017 and has not finalised it. In children the evidence is thin. A systematic review of 6 studies in 15,815 children aged 1 to 18, mostly observational and of low quality, linked plant based milks of any kind with lower BMI, height and blood vitamin D than cow's milk. In the same review, girls with low calcium intake who drank fortified soy milk had higher bone density. None of those numbers give a size, so read them as a direction. The one caution in our cards is about warfarin. A 70-year-old man stable on warfarin fell below his target INR after starting soy milk and returned to range within 2 weeks of stopping, in a single case the authors rated possible to probable. If you take warfarin, starting or stopping a daily soymilk is worth telling the person who checks your INR. Our cards do not cover soy allergy, pregnancy or the unnamed fiber, so this page cannot tell you anything about them.

Sources

1. slpf-r2-01 · composition table
   FDC 175222 SILK Plus Fiber, soymilk: Energy 41 kcal/100 g · Fiber 2.1 g · Protein 2.47 g · Sugars 2.88 g · Calcium 123 mg · Vitamin B12 1.23 µg · Vitamin D 1.2 µg · 1 cup 243 g
   USDA FoodData Central, SR Legacy 2019, FDC 175222 SILK Plus Fiber, soymilk · checked 2026-09-29
2. slpf-r2-02 · randomized crossover trial
   Calcium absorption from fortified soy milk compared to cow's milk was examined using a randomised single-blind acute cross-over design study in 12 osteopenic post-menopausal women ... 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 2026-09-29
3. slpf-r2-03 · crossover trial
   Fractional Ca absorption in CCSM (0.211 +/- 0.057) did not differ from that of cow's milk (0.217 +/- 0.040), but both were higher (P < 0.05) than that of TCPSM (0.181 +/- 0.039).
   J Nutr, 2005 · checked 2026-09-29
4. slpf-r2-04 · meta-analysis of RCTs
   Eligibility criteria were met by 17 trials (n = 504 adults with a range of health statuses) ... The substitution of soymilk for cow's milk resulted in moderate reductions in non-HDL-C (mean difference, - 0.26 mmol/L [95% confidence interval, - 0.43 to - 0.10]), systolic blood pressure (- 8.00 mmHg [- 14.89 to - 1.11]), and diastolic blood pressure (- 4.74 mmHg [- 9.17 to - 0.31]); small important reductions in LDL-C (- 0.19 mmol/L [- 0.29 to - 0.09])
   BMC Med, 2024 · checked 2026-09-29
5. slpf-r2-05 · 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 2026-09-29
6. slpf-r2-06 · 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.
   21 CFR 101.82, Health claims: Soy protein and risk of coronary heart disease (CHD) · checked 2026-09-29
7. slpf-r2-07 · 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. ... 1 study found that adolescent girls with low calcium intake who consumed fortified soy milk had higher bone density compared with those who did not consume soy milk.
   J Nutr, 2024 · checked 2026-09-29