As experts in aging and longevity, we are not big fans of animal milk.
Milk can accelerate aging in various ways. Given milk impacts aging, which is a process that by definition takes a long time, it takes decades for these effects to manifest.
However, milk can even have immediate pro-aging effects, like increasing insulin resistance or increasing the production of insulin drastically, as we will discuss below.
In this article, we will explain several mechanisms by which milk can accelerate aging.
How milk stimulates pro-aging growth pathways
Milk is made by nature to make calves grow quickly. That’s why milk contains many substances to stimulate growth.
However, growth stimulation also accelerates aging.
One red thread through all aging research (biogerontology) is that too much stimulation of growth leads to faster aging.
More precisely, milk contains various substances that stimulate growth receptors in cells, like insulin receptors, mTOR receptors, and insulin-like growth factor (IGF) receptors, making cells age faster.
In biogerontology (the science that studies aging), it’s well-known that stimulation of these pro-growth and aging-receptors (mTOR, insulin receptors, IGF receptors) accelerates aging in animals, increases their risk of aging-related diseases, and shortens lifespan (R,R,R).
It’s striking that milk is a strong stimulator of all these canonical growth receptors that are well-known by aging experts to accelerate aging.
Too much growth stimulation can accelerate aging via many different mechanisms.
For example, too much stimulation of mTOR and IGF receptors causes cells to maintain themselves less effectively; they will repair their DNA less or recycle their components less efficiently.
Too much growth stimulation also makes cells work harder, so they wear out faster. Too much growth leads to more protein production and less protein breakdown (autophagy); accumulation of proteins and stimulation of protein production are two of the hallmarks of aging (see “a decline in proteostasis” and “deregulated nutrient sensing”).
Other mechanisms by which milk accelerates aging
Besides stimulating pro-aging growth pathways, milk can speed up aging in other ways.
For example, milk contains galactose (not to be confused with lactose). Galactose is a milk sugar that accelerates aging.
The doses of galactose scientists give to animals to accelerate aging is comparable to humans drinking several glasses of milk per day. So it’s not that researchers have to give the animals way higher amounts of galactose than can be found in several cups of milk. One glass of milk contains 5 grams of galactose, which is a significant amount.
Another study showed that children can be made insulin-resistant by just making them drink a lot of milk (R).
This is remarkable, because insulin resistance is typically something we mainly see in elderly people. Aging causes a gradual increase in insulin resistance, leading to metabolic diseases and type 2 diabetes (this is also one of the hallmarks of aging, called “deregulated nutrient sensing”).
It’s telling that young children can be made insulin-resistant after just one week by making them drink a lot of milk, demonstrating again the strong effect milk has on pro-aging, pro-growth pathways like the insulin pathway.
Another study found that just drinking one glass of milk with a healthy meal increases insulin production threefold. We know that high insulin peaks in the blood lead to type 2 diabetes. In fact, this form of diabetes is caused by insulin resistance: our cells become numb to the regular high insulin peaks caused by unhealthy meals. Stimulation of insulin receptors also accelerates aging.
The link between milk and disease
Parkinson’s disease is caused by neurons dying off in a specific region in the brain (the nucleus accumbens). Mainly aging causes these neurons to die off (even in healthy, non-Parkinson’s patients), and this process can be accelerated by various factors, such as pesticides and perhaps milk.
Other studies have shown an association between milk consumption and prostate cancer risk (R,R,R). This should not be surprising, given milk strongly induces growth, and cancer is uncontrolled growth of cells (many substances that induce growth can also increase the risk of cancer).
There are also anecdotal stories of men with prostate cancer who see their prostate-specific antigen (PSA levels) go up when drinking milk — and decrease when they stop drinking milk.
Milk also is very good at triggering the immune system. Milk contains various proteins, like casein and lactalbumin, that can irritate and confuse the immune system. Often, people can substantially improve their allergies or eczema by stopping consumption of milk (and dairy products in general).
Milk consumption is also one of the reasons that acne is so much more prevalent in Western societies compared to populations that consume healthier diets (R,R). Various substances in milk strongly stimulate growth hormone production and the production of steroid hormones, which play a role in acne (and also accelerate aging, as we explain here) (R,R,R).
Oh yes, and did we tell you that milk does not lead to a reduction in bone fractures or stronger bones? (R,R,R,R) Some studies even show that more milk intake is associated with more risk of bone fractures (R). This is a story that the dairy industry has been telling people for decades but has proved to be untrue.
Besides the age-accelerating effects of milk, milk is also unhealthy for the planet and causes animal suffering (e.g. cows living in crowded conditions on dairy farms). Cattle farming requires huge amounts of farmland and water.
In short, given the unhealthy long-term effects of milk on both our bodies and the planet, we predict that in the long term, milk consumption will decline to almost zero. But this will likely take decades.
Milk consumption and increased mortality
Given the pro-aging effects of milk, it should come as no surprise that studies show a link between high milk intake and increased mortality.
For example, a large, long-term study found that women who drink three or more glasses of milk per day had almost double the risk of dying compared to women who drank less than one glass per day (R).
There was also a strong dose-response relationship (the more milk they drank, the higher the risk of dying), which suggests a causal relationship.
The study also found that higher milk intake was associated with increased DNA damage and inflammation.
While there are also many studies showing that “milk is healthy,” keep in mind that the dairy industry is large and powerful. Every year, about 850 million tons of animal milk is produced. The dairy industry does it utmost to produce lots of studies demonstrating the health effects of milk. However, these studies are problematic because:
- Often, these studies look at the short-term effects of milk consumption, not its long-term effects. Most studies last only a few months or years. There are very few studies that look at the effects of milk consumption in the long term (over decades). For example, this study that found increased mortality with milk consumption looked at a period of more than 20 years, which is very rare.
- Often, studies look at specific diseases that improve, while ignoring many other diseases for which milk can increase risk. For example, some studies show that a higher milk intake is associated with less risk of colon cancer, but they ignore other studies showing that milk consumption is associated with an increased risk of Parkinson’s disease (R,R,R) or prostate cancer (R,R,R).
- Often, studies lump different dairy products together (they look at milk and cheese and yogurt consumption) to “prove” that milk intake is healthy. However, given yogurt and cheese are healthier than milk, this provides a skewed view of milk consumption.
- Sometimes, the dairy industry changes the findings of studies to claim that milk is healthy. For example, one study found that milk didn’t improve cardiovascular diseases, while the message told to the public was that milk does improve cardiovascular health, leading principal investigator Professor Walter Willett to complain about this re-interpretation of his study findings.
- Mostly, dairy studies are directly or indirectly sponsored by the dairy industry. Often, professors at universities get paid by the dairy industry, directly (as a consultant, for example) or indirectly (by funding the faculty or inviting the professor to conferences). Various entire universities are set up as a spin-off of the dairy industry or to mainly support the dairy and agricultural industry. Research shows that when a study is funded by a company, it is six to eight times more likely to have a positive outcome for the company (R).
- Many nutrition experts (who tout the benefits of milk) are not knowledgeable about aging and longevity. If they don’t know a lot about the important role of mTOR and insulin pathways in aging, for example, it’s more difficult for them to assess the long-term effects of milk intake.
- Many nutrition experts look at milk in a reductionistic way. They look at a few components of milk (like calcium) and not at the bigger picture. Or they mainly base their recommendations on the short-term effects of milk consumption and do not look at the long-term effects. For example, they tout milk because “it is a good source of calcium” or “contains many different amino acids,” even though milk also contains hundreds of other substances, among them those that can accelerate aging, like galactose, insulin, and mTOR-stimulating substances.
So what should I do?
We recommend replacing animal milk (cow milk, goat milk, camel milk) with plant-based milk, such as almond milk, cashew milk, soy milk, etc.
Make sure you take the low-sugar variants (many plant-based milks contain too much sugar, the same for plant-based yogurts).
Also, very importantly, when not drinking animal milk anymore, it’s important to take calcium supplements. Yes, plant-based milk contains some calcium, and green leafy vegetables like broccoli and kale also contain some calcium, but it’s often not enough (even when also consuming cheese and yogurt).
Therefore, we recommend taking 500 mg of calcium, two times per day, and combining this with vitamin D (needed for calcium absorption) and vitamin K (needed to ensure the calcium ends up in the bones and not the arterial walls).
We explain more about how to take calcium properly in our food supplement article.
Why cheese and yogurt but not milk?
We do not recommend consuming animal milk. However, cheese and yogurt can be an exception.
Cheese is a partially digested and fermented form of milk, making it significantly different from milk. Unlike milk, cheese contains vitamin K, probiotics (healthy bacteria for your gut), and less galactose (the sugar in milk that accelerates aging), for example.
However, cheese is still an animal product. We see that reducing the amount of animal products (like cheese, milk, and meat) can improve health and lengthen lifespan (R,R,R,R,R,R,R,R). Also, cheese still contains proteins that can irritate or trigger the immune system, leading to an increased risk of auto-immune diseases, allergies, or eczema.
Therefore, we recommend also limiting your cheese intake.
Regarding yogurt, we ideally recommend eating plant-based yogurt, like soy yogurt or coconut yogurt. Make sure you consume the low-sugar variants; a lot of plant-based yogurt contains high amounts of sugar.
Read our popular ultimate Longevity Diet article to learn more about the best foods and diet for longevity.