Soy drink benefits: swapping it for cow milk dropped blood pressure 8 mmHg — at low certainty

Key benefits

1. 01Early research

   8 mmHg lower on soy instead of cow milk — while the paper's verdict is "few differences"

   2026, Advances in Nutrition. Systematic review and network meta-analysis, registered on PROSPERO (CRD42025638028).

   Methods.

   • Three databases (MEDLINE, Cochrane CENTRAL, Web of Science) and two trial registries
   • Only randomised controlled trials of at least three weeks comparing plant-based drinks with each other or with cow milk
   • Risk of bias by RoB 2.0, certainty of evidence by GRADE
   • Fourteen RCTs, 543 participants — soy, rice and oat drinks and cow milk

   Results.

   Comparison	Outcome	Mean difference (95% CI)	Certainty
   Cow milk 500 mL/d → soy	LDL cholesterol	−0.47 mmol/L (−0.85 to −0.10)	Low
   Cow milk 500 mL/d → soy	HDL cholesterol	+0.01 mmol/L (−0.03 to 0.05)	Moderate
   Cow milk 500 mL/d → soy	Systolic pressure	−8.23 mmHg (−10.90 to −5.55)	Low
   Cow milk 500 mL/d → soy	Diastolic pressure	−7.82 mmHg (−13.61 to −2.02)	Low
   Oat drink vs cow milk	Total cholesterol	−0.12 mmol/L (−0.24 to −0.01)	Very low
   Oat drink vs rice drink	Total cholesterol	−0.23 mmol/L (−0.40 to −0.05)	Very low

   In mg/dL, LDL −0.47 mmol/L is about −18 mg/dL, and oat drink's total cholesterol −0.12 mmol/L is about −5 mg/dL.

   How to read the table.

   First, the verdict and the individual numbers differ. The sentence the authors put first is "few differences were observed". Soy's LDL and blood pressure are the exceptions within that. Lifting a few rows out of the table can create an impression opposite to the paper's conclusion.

   Second, −8.23 mmHg is too large. That size is comparable to a single antihypertensive tablet. When a food intervention produces a figure like that, suspect the limits of the data before the size of the effect. All fourteen trials together hold 543 people, and any one comparison holds far fewer. That is why the authors graded it low certainty, which in GRADE means the true value may be substantially different from the estimate.

   Third, the diastolic interval runs from −13.61 to −2.02 — more than 11 mmHg wide. That is the data failing to pin the estimate down.

   Fourth, this is not "drink soy milk" but "drink soy milk instead of cow milk". The comparator is cow milk, not water or nothing. If you do not currently drink milk, these numbers do not transfer to you.

   Fifth, the dose is 500 mL a day — two and a half cartons. That is a different proposition from a glass now and then.

   Sixth, HDL did not move: +0.01 mmol/L, moderate certainty. And that null result carries a higher certainty grade than the positive ones — the finding that nothing changed is the more trustworthy finding here.

   The honest conclusion:

   • Swapping cow milk for soy can be a reasonable choice, particularly with lactose intolerance
   • But do not make the swap expecting 8 mmHg. The authors graded that number low certainty
   • Their closing sentence calls for high-quality RCTs
   • The grade here is "early research"

   [1]
2. 02Nutrition data

   124 mg of calcium and 1.11 µg of B12 — added at the factory, not grown in the bean

   The table above is for soy drink that is unsweetened and fortified with calcium and vitamins A and D. That distinction is the most important thing in this entry.

   Per 100 g:

   • 33 kcal — low
   • Protein 2.86 g
   • Fat 1.61 g (saturated 0.206 g), carbohydrate 1.74 g, sugar 0.41 g
   • Calcium 124 mg, vitamin B12 1.11 µg, vitamin D 1.2 µg — all fortificants
   • Vitamin B2 0.207 mg, B1 0.154 mg
   • Potassium 120 mg, magnesium 16 mg, sodium 37 mg
   • Cholesterol 0

   Side by side with cow milk (both per 100 g):

   	Soy (fortified, unsweetened)	Cow milk (whole, vitamin D added)
   Protein	2.86 g	3.27 g
   Fat	1.61 g	3.20 g
   Carbohydrate	1.74 g	4.63 g
   Calcium	124 mg	123 mg
   Vitamin B12	1.11 µg	0.54 µg
   Potassium	120 mg	150 mg
   Sodium	37 mg	38 mg
   Cholesterol	0	present

   The calcium is almost identical: 124 against 123 mg. But the soy drink's 124 mg was put there during manufacture, not grown in the bean.

   Unfortified soy drink is a different product. It has almost no calcium, B12 or vitamin D. Soybeans contain no B12 at all. If you are vegetarian and counting on soy drink for B12, check the label for fortification.

   And added calcium settles. Calcium carbonate does not dissolve, so it collects at the bottom of the carton. Pour without shaking and you drink only part of the calcium on the label. Shake it.

   Cow milk is slightly ahead on protein: 3.27 against 2.86 g. Not a large gap, but if you substitute one for the other expecting equal protein, you come up a little short.

   Fat and carbohydrate are lower in soy, and cholesterol is zero.

3. 03Not established

   The soy drink you buy is probably not the soy drink in this table

   This entry is about reading the label.

   The figures above are for unsweetened soy drink. A good share of what sells in Korean shops is not unsweetened.

   Three things to check.

   First, sugar. Unsweetened soy drink has 0.41 g of sugar per 100 g. Sweetened products add sugar on top of that, and cartons carrying more than 10 g per 190 mL are common. Look at the sugar line. The trials in the meta-analysis above generally used drinks without added sweetness.

   Second, fortification. Calcium 124 mg, B12 1.11 µg and vitamin D 1.2 µg are numbers that were put there. Unfortified products have essentially none of the three, and B12 is not present in soybeans in the first place.

   Third, soy content. Soy drink is ground soybean in water, so the proportion of water sets the protein. Whether the protein line reads near 3 g or around 1 g per 100 mL tells you a lot.

   One common claim, handled honestly.

   The idea that soy isoflavones affect male hormones has circulated online for years. This site has not yet published a clinical paper it has verified on that question. So no conclusion is drawn here in either direction. It will be added as its own entry once the evidence is checked. Declaring it safe and warning that it is dangerous are the same kind of error without evidence.

   Only what can be stated with confidence:

   • With lactose intolerance, soy drink contains no lactose
   • With cow's milk allergy, soy drink is an option — but not with soy allergy
   • Do not give soy drink to an infant in place of formula. Ordinary soy drink is not infant formula
   • If you take levothyroxine for your thyroid, soy products have been noted to interfere with its absorption. Separate the timing and speak to your doctor

How to eat it well

What to watch out for