Soy vs dairy: Is one better than the other?

Proponents of soy milk tout it as a natural, plant-based source of protein and point to research that shows that soy milk lowers LDL (low density lipoprotein), or “bad” cholesterol in the body, thereby cutting a person’s risk of developing heart diseases. Soy critics argue that soy contains phytoestrogens, which are thought to increase risk of certain cancers.

How do you, as a consumer, make an informed choice? To help you, we discuss here some important questions about soy and cow’s milk, namely:

  1. What is the difference between soy and cow’s milk?
  2. Should people with gout avoid soy?
  3. Is soy or dairy better for patients with cancer?

Difference between soy milk and cow’s milk (dairy)

Soy is a good source of low-fat and plant-based protein. It is cholesterol-free, has less saturated fat than cow’s milk and lowers the LDL in the body. Cow’s milk, on the other hand, has more calcium than natural soy. Calcium, as we know, helps to build bones and prevents osteoporosis. Cow’s milk also contains more vitamins, such as vitamin B12 and vitamin D.

These days, however, commercially made soy milk is often fortified to have calcium and nutrients similar to cow’s milk. At the same time, cow’s milk now comes in low-fat versions and these sometimes have lower saturated fat than commercial soy milk (see table below).

Both calcium-fortified soy milk and low-fat milk are good sources of protein and calcium. "However, there is evidence that soy products, together with a diet low in​ saturated fat, can help to lower LDL levels, and hence reduce the risk of heart disease," shares Ms Joey Ho, Dietitian from the Nutrition and Dietetics Department at KK Women's and Children's Hospital (KKH), a member of the SingHealth​ group.

​Nutrient ​ ​Soy milk ​Milk ​
Per 250ml ​Natural ​Fortified (High calcium, reduced sugar) ​Full cream ​Low fat, high calcium
​Energy (kcal) ​143 ​143 ​175 ​110
​Protein (g) ​10 ​10 ​8.3 ​8.8

​Fat (g)
Saturated fat (g)

​5.5
(0.8)

3.8
(1)

10.6
(6)

2.5
(1)

​Cholesterol (mg) ​0 ​0 ​29 ​63
​Calcium (mg) ​63 ​500 ​280 ​500

If I have gout, should I avoid soy?

Many people think that if you suffer from gout, you should not eat any soy. This is not totally true. Gout is due to excessive uric acid in the blood, which causes crystal deposits to form in the joints, leading to inflammation and pain. Uric acid is derived from purine, which is found in protein-containing foods such as soy.

If you suffer from gout, it is important to lose weight if you are overweight. Drink adequate fluids; restrict alcohol intake and refrain from eating large meals. As for food, you should avoid fatty foods and foods which are high in purine. Foods like soy, which are moderate in purine, can be consumed in moderate amounts as part of a healthy and balanced diet.

Food Group ​Low Purine ​Moderate Purine ​High Purine
​Rice & alternatives ​White rice, refined bread, cereals ​Brown rice, wheat bran, oats ​-
​Vegetables ​Most vegetables Mushrooms, peas, spinach, asparagus, cauliflower ​-
​Fruit ​All fruits and juices ​- ​-
Meat & alternatives (Limit to 2 servings per day)

Milk and dairy products

Fish, chicken, bean soy products, nuts, eggs

Liver, organ meat, sardines, herring, mackerel, ikan bilis (dried anchovies), scallops

​Seasoning ​- Baker’s and brewer’s yeast, Vegemite

Meat extracts, stock cubes

If I am a cancer patient, are soy or dairy products better for me ?

Cancer patients in general require a high-energy and high-protein diet. Both soy and dairy products are good sources of protein and should benefit a patient who is undergoing cancer treatment. Some people think that soy and dairy are associated with increased breast cancer risk. However, there is no strong scientific evidence to support this claim.

Although dairy products contain hormones, the amount presented is too little compared to hormones produced in the human body. There is no strong evidence showing that hormones in dairy can cause cancer. An average of 2 to 3 servings of dairy daily can help to increase overall protein intake in cancer patients, i.e. 1 serving is equivalent to 1 cup of milk, 1 small tub of yoghurt or 2 slices of cheese. Full fat dairy is useful to increase overall energy intake, however reduced fat dairy is still recommended for patients who are overweight or obese.

Isoflavones, a phytoestrogen present in soy, has been linked to increased risk of breast cancer, however soy foods do not contain high enough level of isoflavones to cause breast cancer. Moderate consumption of 1 to 2 servings of soy and soy products daily are considered safe for cancer patients, i.e. 1 serving is equivalent to 1/3 cup tofu, 1 cup soy milk or ½ cup of soy nuts. Intake of concentrated soy supplements should be avoided in all forms in view of limited convincing evidence on its effect on breast cancer risk.

Ref: K21

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