When it comes to heart health and managing LDL-cholesterol levels, the type of milk you choose can make a surprising difference. As a functional nutritionist in Singapore specialising in cardiovascular health, clients often ask: “Is soy milk or cow’s milk better for reducing cholesterol?” Let’s dive into the evidence to find out.
A Quick Intro: Why LDL-Cholesterol Matters
LDL (low-density lipoprotein)-cholesterol is often referred to as “bad cholesterol” because high levels can lead to plaque buildup and clogged arteries, increasing the risk of heart disease. So, making specific food choices—like selecting the right milk—can be an important part of keeping your heart healthy.
The Two Contenders: Soy Milk vs Cow’s Milk
For this comparison, we’ll look at unsweetened (unfortified) soy milk and reduced-fat (2%) cow’s milk, which are commonly used in research. We’ll break down
- the macronutrients (protein, fats, carbs),
- the micronutrients (vitamins and minerals),
- their direct effects on LDL-cholesterol, and
- a special “superpower” that gives one of these milks an edge.
Macronutrient Breakdown
Calories
- Soy Milk: 91.5 kcal per cup
- Cow’s Milk: 122 kcal per cup
Both milks are considered nutrient-dense for their calorie content—so it’s a tie here.
✅ Score: 1 star each for both soy milk and cow’s milk
Fat Content
- Soy Milk: 5 g total fat
- 0.7 g saturated
- 1.1 g monounsaturated
- 2.9 g polyunsaturated
- Cow’s Milk: 4.6 g total fat
- 2.7 g saturated
- 1 g monounsaturated
- 0.1 g polyunsaturated
Both milks contain similar amounts of total fat. However, most of the fat in cow’s milk comes from saturated fats (SFAs), while most of the fat in soy’s milk comes from polyunsaturated fats (PUFAs).
Saturated fats increases LDL-cholesterol levels, while polyunsaturated fats help lower it. Soy milk wins this round.
✅ Score: 1 star for soy milk
Protein
- Soy Milk: 9 g per cup
- Cow’s Milk: 8.2 g per cup
Both milks provide comparable amounts of 8–9 g of protein per cup. Soy protein is also considered a high-quality protein with a high protein digestibility score that is comparable to animal protein.
✅ Score: 1 star each for both soy milk and cow’s milk
Carbohydrates
- Soy Milk: 3.1 g per cup, of which 0.5 g sugars
- Cow’s Milk: 12 g per cup, of which 11.9 g sugars
On the surface, cow’s milk looks like it contains more carbs and sugars, but most of this is naturally-occurring lactose. While this isn’t an issue for everyone, it’s worth noting that around two-thirds of Asians are lactose-intolerant. For those in Singapore and surrounding regions, this could be an important factor.
✅ Score: ½ star for soy milk (for the lactose-intolerant)
Summary of Macronutrients: Soy Milk vs Cow’s Milk
From a macronutrient point of view, soy milk vs cow’s milk now stands at 3.5 stars vs 2 stars.
Will this change after we analyze the micronutrients? Let’s take a look!
Micronutrient Match-Up
Vitamin A
- Soy Milk: 0.1 μg
- Cow’s Milk: 203 μg
Cow’s milk usually contains 15-25% of the recommended daily requirements for vitamin A, while soy milk contains only a trace amount.
Vitamin A plays an important role in maintaining a healthy immune system, which would help to lower chronic inflammation—a contributor to clogged arteries.
✅ Score: 1 star for cow’s milk
Potassium
- Soy Milk: 410 mg
- Cow’s Milk: 388 mg
Both soy milk and cow’s milk contains a good amount of potassium.
Potassium supports healthy blood pressures. High blood pressure damages arteries, making it easier for LDL-particles to get trapped, forming plaque and clogged arteries.
✅ Score: 1 star each for soy milk and cow’s milk
Calcium
- Cow’s Milk: 307 mg
- Soy Milk: 10 mg
Cow’s milk is one of the best natural foods source of calcium. Although soy milk is often fortified, calcium in cow’s milk is suggested to be more bioavailable as it is found in its natural food matrix.
It is also suggested that naturally-occurring calcium reduces the absorption of cholesterol.
✅ Score: 1 star for cow’s milk
Summary of Macronutrients: Soy Milk vs Cow’s Milk
Including the micronutrients, soy milk vs cow’s milk is now 4.5 stars vs 5 stars.
But what does the research say when we compare soy milk and cow’s milk directly in terms of their LDL-lowering effects?
And the LDL-Cholesterol Winner Is…
Let’s bring in the science. A meta-analysis of 17 randomised controlled trials compared the impact of soy milk and cow’s milk on heart health markers.
The results?
Replacing 2 cups of cow’s milk with soy milk daily led to a 0.19 mmol/L (7.2 mg/dL) reduction in LDL-cholesterol—about a 6% drop from baseline.
🎉 Winner for reducing LDL-cholesterol: Soy Milk!
The Superpower of Soy Milk – Isoflavones
Here’s where soy milk really shines.
Soy milk contains isoflavones, plant compounds with powerful antioxidant and anti-inflammatory effects, including the ability to lower LDL-cholesterol.
This second meta-analysis showed that consuming around 96 mg of isoflavones daily (compared to just 6 mg) resulted in a 0.15 mmol/L (5.7 mg/dL) reduction in LDL-cholesterol.
The recommended amount of isoflavones intake is 25 mg/day. How much soy foods does that correspond to? I’ve created a free PDF listing common soy foods and their isoflavones content that you can download here:
Final Thoughts: Which Milk Should You Choose?
Both milks offer health benefits—but your best choice depends on your health goals.
- If you are not concerned with cholesterol, or you already include a lot of LDL-cholesterol lowering foods in your diet, then cow’s milk can be a good option.
- If you’re lactose-intolerant or trying to further reduce LDL-cholesterol, soy milk should be your go-to.
Either way, both can be part of a heart-healthy balanced diet when consumed mindfully.
If you’d like to watch a video version of this, you can click below.
