In the previous part of this series, I talked about protein timing. Let’s end the section on protein by discussing two controversial protein sources – milk and soy.
They are controversial because they supposedly increase the amount of estrogenic activity in the body.
Soy contains phytoestrogens in the form of isoflavones, which are plant-based compounds that weakly mimic estrogen by binding to and activating the estrogen receptors in the body. They do not activate the pathway as much as actual estrogen, hence the use of the term “weakly”.
Milk on the other hand is controversial because it contains actual mammalian estrogen.
In this piece I will give you some background information and get the easy one out first (milk). Soy demands a longer discussion and I’ll get to that in the next piece.
Background Information You Need
Before I get into this topic, I need to give you some background on estrogen because based on the discussions I’ve had with people about it, most people have little to no idea about the subject.
In general, men think it’s the devil’s hormone that they should have absolutely none of. Which is of course wrong.
What is a Hormone
Hormones are chemicals produced by the endocrine glands (pituitary, thyroid, adrenal glands, ovaries, testes, etc.) that (usually) travel through the bloodstream and affect target tissues throughout the body over long periods of time.
Basically anything that causes something else to happen somewhere else – either in some particular other place or globally over the body.
This is one of the ways they differ from neurotransmitters which are released by the nerve cells that cause something to happen in the nearby cells.
The simple way to understand them is with the lock and key analogy.
The cells in the body have various locks (receptors) that when activated, tell the cell to do something (initiate, increase, decrease, or stop specific processes in the cell).
Hormones are the key to the lock. They unlock specific locks (bind to their receptors).
There are other things that are not hormones that can also bind to these receptors and can mimic the effects of hormones.
The thyroid gland produces two thyroid hormones: thyroxine (T4) and triiodothyronine (T3). Most of the body’s cells have receptors for the thyroid hormones.
T3 and T4 travel all across the body and reach most of the body’s cells. They bind to their receptors.
In the particular case of these hormones, they tell the cells how quickly they should use energy and how rapidly they should do their processes. From a macro perspective, they regulate heartbeat, digestion, body temperature, and your breathing rate.
As you can already tell, both too much and too little of any hormone can produce problems.
What is Estrogen
Estrogens are a family of hormones (usually referred to in the singular and I will do so as well) that have a primary role in regulating sexual development and reproductive system. This is why it’s also called a “sex hormone”.
Note that estrogen does more than sexual/reproduction related things even though the public is only aware of it in the sexual development sense.
Estrogen in its optimal quantities does very useful things for both men and women. All of that is well beyond the scope of this series of articles.
Having very high estrogen levels can cause various problems for both genders.
Men get gynecomastia (breast tissue enlargement), erectile dysfunction, reduced sperm count, increased fat gain, fatigue, etc.
Women get irregular menstrual cycles, increased fat gain, breast fibroids, uterine fibroids, etc.
Note that mildly elevated estrogen is quite anabolic (assuming testosterone is not low). It protects against muscle breakdown, improves exercise induced gains, and promotes increases in bone mass, density, and strength. But that’s beyond the scope of this series.
Low estrogen also causes problems but the context of this piece is milk raising estrogen levels so I’m going to stick to it.
The main thing we need to see if milk is safe to eat is to see if it can cause any meaningful increase in estrogenic activity.
The Types of Estrogen
There are 4 main types of estrogen:
| Name and Potency | Notes |
| Estradiol (E2) Also known as oestrogen Potency is 100% (Reference value) | The most potent and abundant estrogen during the reproductive years. It is produced by the ovaries in women. Men get it from peripheral aromatization of testosterone by fat cells, liver, testes, and within the brain. This is why being obese increases estrogen levels and decreases testosterone levels in men. The increased fat cells convert more testosterone to estrogen than would be optimal. |
| Estrone (E1) Also known as oestrone Potency is 10-25% | This is a weaker estrogen that is only 10-25% as potent as E2. It’s the main estrogen in women after menopause (their ovarian production of E2 falls). Men have very minor amounts of E1. Estrone (E1) and estradiol (E2) can convert into each other as needed. |
| Estriol (E3) Potency is ~10% | Weak estrogen and found in pregnant women. |
| Estetrol (E4) Potency is less than 1% | Very weak estrogen and only found to be produced in pregnant women by the fetal liver. Irrelevant to our discussion. |
How much estrogen does the human body produce per day?
It would be nonsensical if I just said “milk and soy have estrogen and are unsafe to drink”. We have to know how much estrogen they’ve got and how much estrogen production happens in the human body.
If you produce 100 units and you add another 100 units, you’ve increased the quantity by a lot and doing that would be a bad idea. If you produce 100 units and add 1 more unit, it would be a rounding error and nothing to be concerned about.
Unfortunately the vast majority of the public doesn’t get this and they think of everything in terms of absolutes. Either something is “healthy” or “unhealthy”. Good or bad. But that’s not how things work in real life.
Let’s see how much estrogen we produce on a daily basis.
Daily Estrogen production in humans
| Estrogen type | Daily production in men | Daily production in women |
| Estradiol (E2) | 40-50 μg | 100-400 μg depending on where they are in their cycle |
| Estrone (E1) | 150 μg | 100-400 μg depending on where they are in their cycle |
Estrogen in Milk And Dairy Products
Milk has E1, E2, and E3 in both free and conjugated forms.
We only care about the free form of estrogens because they can bind with the estrogen receptors in the human body.
Conjugated estrogens are inactive at receptors. This means they are not absorbed by the gut and just get pooped out (by and large – a small fraction can be de-conjugated by gut bacteria and re-absorbed).
Here is how much of each of the free estrogens are present in one liter of whole and skimmed milk:
As you can see, the amount of estrogen in milk is tiny compared to what your body produces every day. Literally about 0.01% as much as your endogenous daily production.
And this is for a whole liter of milk.
As you can see, despite what some ill-informed influencer told you, worrying about estrogens in milk is nonsensical.
Addressing some other controversies about milk
Now that I did end up making a post on milk safety, let me address some other controversies that have been created around milk.
Again, you are more likely to be familiar with them if you’re part of some extremist dietary cult (vegan, carnivore, etc.).
Bovine/cow Growth Hormone (rBST)
This is a protein that has no effect in humans because it gets broken down in the small intestine before it enters your bloodstream.
Even if it wasn’t broken down, it would still have almost no effect because humans have a different growth hormone called Human Growth Hormone (HGH). Your body does not have receptors for rBST (bovine GH has very low cross-reactivity with human GH receptors).
Complete non-issue that gets blown up because it sounds scary to people who don’t know any better.
Insulin-like Growth Factor (IGF-1)
This is a normal peptide (short chains of amino acids are called peptides) that is produced by the body and is needed by many cells.
Similar to the estrogen discussion above, the amount of IGF-1 in milk is tiny compared to what the body produces (1-10 μg/L in milk vs 10,000 μg/day in adult humans).
Even when cows are treated with rBST/rBGH, it only elevates IGF-1 by 2-3 μg/L. Not to mention that most of it is broken down during digestion anyway.
Clearly a non-issue. Of course influencers are not well informed and can fearmonger you into thinking it’s going to give you cancer. Unless you’re injecting yourself with large quantities of IGF-1, you don’t have to worry about it at all.
Saturated fat
This is not automatically a bad thing but I will get to it later in the series when we discuss dietary fats. Don’t want to have too much overlap in this series. The short version is that if your total fat consumption isn’t too high, don’t worry about it.
The final verdict: You can have as much milk and dairy products as you like. It is completely safe.
There is no issue with milk whatsoever.
People have been drinking milk for as far back as pre-history. The earliest confirmed evidence of humans drinking milk is 7th millennium BCE. 9000 years ago.
It is a great source of calcium and many other micro-nutrients. The protein quality is really high and it can form the primary protein source for vegetarians.
It goes without saying that to drink milk you need to be lactose tolerant. If you’re lactose intolerant, try this.
In the next piece, I’m going to talk about soy and if it’s safe to eat or not. Soy is a bit more complex than milk and warrants its own piece.
– Harsh Strongman
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