Is milk the perfect food for creating acne? That’s what a 2011 paper reviewing how diet affects acne said.

In summary, it would appear that milk is ‘nature’s perfect food’ for the creation of acne. Not only does it induce increased amounts of IGF-1 and insulin, which together sensitize the androgen receptor in androgen-responsive cells, but it is also capable of supplying those androgen-responsive cells with dairy-derived androgens and their 5α-reduced precursors to appropriately stimulate them. At the same time, the endogenous androgens produced by the ovaries, testes, adrenal glands, and by the intracrine system of the pilosebaceous units themselves, are given open access to the de-repressed androgen receptors in these androgen-sensitive cells.

Danby, F. W. Acne: Diet and acnegenesis. Indian Dermatol Online J 2, 2–5 (2011). https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3481796/

Let me translate that to real English for you. Drinking milk triggers the release of IGF-1 and insulin hormones. These hormones not only directly stimulate sebum production and skin cell growth, but they also make the skin more sensitive to androgen hormones. In short, milk delivers a devastating one-two punch to the skin.

People who drink milk are more likely to get acne

Several studies have shown that milk consumption correlates with acne, meaning that those who drink more milk tend to also have more acne. Two studies including more than 10,000 teenagers (one study with girls and one with boys) showed that those who drank the most milk (>2 servings per day) had 20% higher risk of acne as compared to those who drank the least (<1 serving per week). (Source: Adebamowo et al. studies in the references)

These studies may underestimate the risk in adults as the same hormones that cause acne are very active during adolescence. An Italian study in slightly older people found 78% higher risk of acne among those consumed the most milk, although the authors mentioned that this study may overestimate the risk.

What’s important is not the exact percentage but the central finding that milk consumption seems to increase the risk of acne.

Though these studies don’t prove that milk causes acne (because they are epidemiological studies) they are enough to take the possibility seriously. Especially when you consider that dairy products increase the same hormones that are linked to acne.

Hormonal effects of milk

IGF-1

One study in older adults showed that three servings of milk per day for 12 weeks increased IGF-1 levels by 10%. Another study in adult men showed 16% higher IGF-1 levels in those who drank 1-2 servings of milk per day as compared to those who drank it only rarely.

A study on Mongolian children who had not previously consumed milk showed 23.4% higher IGF-1 levels after daily consumption of 710ml of UHT milk for four weeks.

Over 99% of the IGF-1 in the blood is bound to various binding proteins. The binding proteins render IGF-1 inactive and thus not bioavailable. The above studies also show that drinking milk reduces the levels of IGF binding proteins and thus increases the amount of free and bioavailable IGF-1.

Insulin

The effect of milk on insulin levels is also well-known. Insulin index measures how much a 240 kcal portion of a particular food increases insulin levels. White bread is used as the reference food. Here are the insulin index values for a handful of foods:

• White bread: 100
• White rice: 79
• Eggs: 31
• Beef: 45
• Yogurt: 115

Unfortunately, insulin index has only been measured for 38 foods, and that list doesn’t include milk. But the extremely high value for yogurt shows how much dairy products affect insulin levels. You can see insulin index values for other foods here: https://www.mendosa.com/insulin_index.htm.

In 2001 Swedish researchers compared insulin responses to white bread, regular milk, and various fermented dairy products commonly eaten in Sweden. Their results showed that dairy products trigger a similar insulin response than white bread. They calculated insulin indexes of 90 and 98 for regular milk and fermented milk respectively.

A pair of studies by Danish researchers showed the dramatic effect of milk on insulin and IGF-1 levels in 8-year old boys. The boys were given either 250g of lean meat or 1.5L of skim milk per day (equal protein content). After just one week fasting insulin levels increased by 103% and fasting IGF-1 levels by 19% in the skim milk group, while there was no change in the lean meat group.

In another study, Swedish researchers showed that addition of 200ml of milk to a low GI meal increased insulin levels by 2.8 times, to similar levels seen with high GI meals. A glass of milk turned the low GI meal into a high GI meal.

Milk also contains other hormones. Some of these may affect acne, but we don’t have enough evidence to say much about them.

Milk allergy and lactose intolerance

Not all ‘milk acne’ is hormonal. Some people are allergic to milk or have lactose intolerance. Milk allergy also has a less severe form, known as milk protein intolerance. Both milk allergy and milk protein intolerance can trigger an immune reaction, and this may trigger acne.

Lactose intolerance can cause gut problems, which are linked to acne.

Unfortunately, there are no studies to support or refute either of these possibilities. Regardless, if you suffer from these conditions you should have several non-acne related reasons to avoid milk.

Is it ok to eat yogurt?

Yogurt can be both helpful and harmful for acne patients. Homemade and ‘live’ yogurts contain probiotic bacteria and as such can be useful in gut issues, and a 2010 Korean study showed that a lactoferrin-enriched, fermented dairy beverage reduced both acne and sebum production. The studies that found a link between dairy products and acne found no such link between fermented dairy products and acne.

On the other hand, there’s no question that yogurt increases both insulin and IGF-1 levels, although there’s some evidence that yogurt increases IGF-1 levels less than milk does. The fermentation process deactiv And this is where the science ends. To go further, you again have to resort to experimentation. It’s likely that yogurt will cause problems for people with hormonal-type acne. What happens in other acne types is not clear. Fermented foods, in general, are a mixed bag for people with gut problems.

Milk alternatives

What about milk alternatives? Are they any better for your skin?

• To my knowledge, goat’s milk doesn’t increase insulin and IGF-1 levels as much as cow’s milk, but I don’t have any reliable data on this. Anecdotal reports from acne forums suggest goat’s milk is safer for acne.
• Soy milk, see the page on phytoestrogens. Consuming phytoestrogens can reduce estrogen levels, and thus could be very problematic for women with hormonal-type acne. Assuming no soy allergies, people with other types of acne could do well with soy milk. Test and see what happens. Soy may also be problematic for people with gut issues. Test carefully.
• Rice, nut and other ‘milks’. Aside from possibly high sugar content, I can’t think of a way these would harm your skin.