Don’t Milk It

Today, the effects of dairy milk on our health. And we start with the so-called “milk pus test”—that’s actually what it’s called—and what it tells us about the U.S. milk supply.

Dairy cows might normally live for about 20 years, but they are typically slaughtered for hamburger after they’re just a few years old when they produce less milk and their profitability drops. But another leading cause of cow culling is mastitis––udder inflammation and infections––which affect 99.7 percent of all dairy operations in the United States.

Because of the mastitis epidemic in the U.S. dairy herd, the dairy industry continues to demand that American milk retain among the highest allowable “somatic cell” concentration, nearly twice as much as the rest of the world—750,000 cells per milliliter.

The concentration in milk from healthy udders should be less than 100,000. These somatic cells are mostly white blood cells, so when you get up to around 200,000, which is like a million per teaspoon, the udder is likely to be infected. So, the somatic cell counts in the bulk milk tanks reflect the level of infection. Basically, if the bulk milk tank, which can hold thousands of gallons, averages 200,000, then 15 percent of the contributing cows are likely infected. At a concentration of 400,000, which is more in line with international standards, a third of the cows are likely infected. And staying within the 750,000 U.S. limit for Grade A milk could reflect that about two-thirds of the cows are infected.

Now, somatic cells are not synonymous with pus cells, as has sometimes been misleadingly suggested. Just as normal human blood and breast milk contain low levels of white blood cells, so does milk from healthy cows. That’s something we’ve known about for more than a century. The problem is that many of our cows are not healthy.

According to the latest national government survey, about one in four dairy cows in the United States suffers from clinical mastitis, the second leading cause of death on dairy farms. This is why the average somatic cell concentration of U.S. milk is that of a likely infected udder at 204,000 cells per milliliter. How much actual pus does that translate to?

Although the industry doesn’t like to talk about pus cells, the fact that pus is present in milk from inflamed mammary glands is a given. But what constitutes pus in milk? The quote-unquote “milk pus test” was introduced more than a century ago. It pooled milk from infected cows that was estimated to contain up to 2.5 percent pus by volume. And we’d really like to see no more than like 0.1 percent. So, what does 204,000 cells per milliliter, the national U.S. average, translate to?

That’s a million cells per teaspoon of milk. A million cells per spoonful sounds like a lot, but pus is really concentrated. So, how much pus is there in a glass of milk? Not much. If you take the national average and subtract the number of white blood cells you might see in normal milk, you get about 100,000 inflammatory white blood cells per milliliter, or about 25 million per cup. Then, it just depends on the cellular concentration of pus.

Although straight pus may have 80,000 cells per microliter or less, to be conservative, the most concentrated I could find for straight pus was about 150,000. Note that’s per microliter, not per milliliter. So, if there are about 25 million cells per cup, and a microliter of pus contains about 150,000 cells, that would come out to be about 150 microliters of pus per glass of milk. There are about 50 microliters in a drop; so, there’d only be a few drops of pus per glass on average.

And you can apparently taste the difference. One of the major problems associated with mastitis is the flavor and texture defects. Milk with high somatic cell counts looks the same, but evidently doesn’t smell or taste as good.

The large amounts of pus in mastitic milk may be aesthetically objectionable, but it’s important to note this is not a food safety issue, thanks to pasteurization. The dairy industry emphasizes that ingesting large amounts of bovine white blood cells has not been shown to be harmful. No matter how inflamed and infected udders get, the pus gets cooked. But just as parents may not want to feed their children fecal bacteria in meat, even if it’s irradiated fecal bacteria, as the Director of the Food Policy Institute put it: “Irradiated poop won’t make you sick, but it’s still poop.” Parents may not want to have their children sip pasteurized pus.

In our next story, we look at the role milk may play in triggering Parkinson’s disease.

Parkinson’s disease is a neurodegenerative brain disorder that affects millions of people. What causes it? Well, if you look at lifestyle factors associated with Parkinson’s disease, the strongest dietary association with increased risk of Parkinson’s disease is dairy consumption. In fact, dairy products are the only food group that has been consistently associated with a high risk of developing Parkinson’s. Five large prospective studies have confirmed the link…including the two Harvard cohorts, the Harvard Nurse’s Health Study and other Health Professionals, which followed more than a hundred thousand peoplefor decades, in the largest analysis of dairy and Parkinson’s disease to date, analyzing more than 1,000 newly diagnosed cases––and all the studies found a link between dairy and Parkinson’s, most finding a significant link. About 50 percent increase in risk overall in those drinking the most milk compared to those drinking the least, at a p value of less than 0.00001, meaning less than 1 in 100,000. You’d only get a finding that extreme by chance. Okay, but why is there a link at all?

Despite clear-cut associations between milk intake and Parkinson’s disease incidence, there is no rational explanation, concluded one review. A year later though, we got a clue. Midlife milk consumption and substantia nigra neuron density at death. What does that mean? Parkinson’s is caused when most of the nerve cells in a critical part of the brain are killed off. And so, if you go back and see how much milk people were drinking in their 40s, 50s, and 60s, and then look at their brains on autopsy and count how many of those critical neurons they had left, in every single quadrant, neuron density was maximized in those who consumed no milk, and lowest in those who consumed the most milk. Even after removing the Parkinson’s cases, those drinking two cups of milk a day had up to 40 percent fewer nerve cells in that critical brain region. What’s in milk that could be wiping out brain cells? Among those who drank the most milk, residues of the pesticide heptachlor epoxide were found in nine out of 10 brains. Aha, so maybe the finding of pesticide residues more commonly in the brains of those who drank the most milk could explain how milk could be cause-and-effect related to Parkinson’s disease risk.

Now, that’s not the only potential explanation. Remember my video on how meat contains that clumpy neurotoxic protein alpha-synuclein? Well, dairy products may contain trace amounts as well, but we don’t have confirmation of that. Could the milk sugar galactose be the missing link? That’s what lactose in milk breaks down into in the body, and galactose is what’s used to induce aging, to experimentally cause aging in the brain. When you drink it, the galactose is picked up by your brain within a few hours, and for doses above 100 mg/kg, it appears that galactose can cause pathological alterations in brain cells, similar to those observed in Parkinson’s disease. And these quantities can be reached and surpassed with the simple daily consumption of two glasses of milk, the main dietary source of galactose in humans. And, of all your brain cells, those dopaminergic neurons, the ones that you need to retain to prevent Parkinson’s may be more vulnerable to galactose-induced damage, galactose-induced oxidative stress.

Galactose may also explain the findings linking milk-drinking with higher death rates. Now, you may be thinking, well duh, the saturated butterfat is just cutting people’s life short. But higher mortality with high milk consumption is observed irrespective of the milk fat content. Skim milk might be fat-free, but it’s not lactose-free.

Can’t you just use lactose-free milk? What about Lactaid? That has the lactase enzyme added to make lactose-free milk. But it just breaks down the lactose into galactose in the carton rather than in your gut. So, you’re still ingesting the same amount of galactose. Perhaps, no wonder then that greater milk intake at midlife may be associated with a greater rate of cognitive decline. I mean, researchers use galactose to create brain aging in the laboratory. Administration of D-galactose, a metabolic derivative of lactose, has been extensively used to mimic cognitive aging through oxidative stress in animal models. Compared to those who said they “almost never” drink milk, those drinking more than a glass a day appear more likely to suffer a global decline in their cognitive function.

Finally today, how to reduce the risk of premature death from dairy consumption.

In my video on milk and bones, I discussed this set of studies, following 100,000 people for up to two decades, finding a 60 percent higher risk of hip fracture among women who drank a lot of milk. The researchers suggested it might be due to the galactose, which is a breakdown product of the milk sugar lactose, based on the fact that people with high levels in their blood––because they were born with an inability to detoxify the stuff––can end up with weakened bones. But that’s not all galactose can do.

Galactose is what scientists use to cause accelerated aging in lab animals, since it’s so successful at mimicking aging by inducing degenerative changes in the brain, heart, lungs, liver, kidney, etc. “The life-shortened animals showed neurodegeneration, mental retardation and cognitive dysfunction, … diminished immune responses, and a reduction of reproductive ability.” And, it doesn’t take much—just the human equivalent of one to two glasses’ worth of milk a day.

However, humans aren’t rodents. For example, we’ve known for nearly a century that you can cause cataracts in rats by feeding them a lot of lactose or galactose, but the epidemiological data is mixed as to whether dairy is doing the same in people.

The Swedish studies didn’t just look at bones, though, but milk and mortality. More milk was associated with more death. In women, three glasses of milk a day was associated with nearly twice the risk of dying prematurely. The medical journal editorial accompanying the study emphasized that, given the rise in milk consumption around the world, “the role of milk in mortality needs to be established definitively now.”

With the then-largest-ever study on milk intake and mortality suggesting such adverse effects, Harvard researchers stepped in with three of their cohorts to form a study twice as big to see if the earlier findings were just a fluke. Following more than 200,000 men and women for up to three decades, they confirmed the bad news. Those who consumed more dairy lived significantly shorter lives. Every half serving more of regular milk a day was associated with nine percent increased risk of dying from cardiovascular disease, 11 percent increased risk of dying from cancer, and an 11 percent increased risk of dying from all causes put together. This is all the more remarkable since milk drinking is typically associated with healthier habits, like more exercise and less smoking and drinking, though they did try to control for all these factors.

Of course, it does matter what you eat instead. This Harvard analysis, published in the New England Journal of Medicine, found that swapping dairy for meat – red meat, poultry, or fish – would not be expected to do your body any favors, and you would be expected to live longer eating dairy than eggs or processed meat. It’s only when you swap dairy for plant-based sources of protein did they find a significant drop in mortality risk.

When all of the milk and mortality studies are put together, it appears the excess mortality risk is limited to regular as opposed to low-fat (like skim) milk. This suggests it may be more of a saturated fat issue, though that doesn’t explain why soured (or fermented) milk appears to have the opposite impact. So, maybe it’s both the butterfat and the galactose. A randomized crossover study of low-fat dairy, fermented dairy, and unfermented dairy found that study subjects had significantly higher IL-6 inflammation levels during unfermented regular dairy weeks, compared to when they were switched to either the fermented or low-fat dairy products. The fermentation process can eliminate some of the galactose.

As we age, our ability to detoxify galactose declines by as much as 40 percent, which would make it even more important to avoid dairy later in life––if indeed galactose is the culprit. But if galactose does its dirty work through oxidation and inflammation, might increased fruit and vegetable intake help mediate some of the harm? In animals, galactose-induced aging can be slowed by fruit and vegetable consumption. For example, feeding rats blueberries can decrease the brain damage induced by the milk sugar. Might it be able to help with the higher levels of oxidative stress and inflammation found among human milk-drinkers? Unfortunately, women drinking three or more glasses of milk a day had more than twice the risk of hip fractures compared to women drinking less than a glass a day, regardless of whether they were eating more or less fruits and vegetables. But those high milk consumers consuming five or more servings of fruits and vegetables a day did reduce their chance of dying prematurely to just 60 percent greater than those drinking less milk; so, antioxidant-rich foods may be able to modify the elevated death rate associated with high milk consumption.

Highly influential advocacy organizations, such as the U.S. National Osteoporosis Foundation or the Europe-based International Osteoporosis Foundation, continue to push dairy, drugs, and calcium supplements, despite the countervailing evidence that I’ve reviewed. Why do they keep pushing dairy, drugs, and supplements? Perhaps because their objectivity is compromised by the influence of their commercial sponsors that include companies that market—you guessed it—dairy, drugs, and supplements. Most recent reviews on dairy and osteoporosis in the English-language medical literature were found to be written by those with ties to the dairy industry. The primary justification for inclusion of dairy in federal nutrition recommendations is based on purported bone benefits that are not supported by the available evidence.

What if dietary guidelines were fashioned without commercial influence? In 2019, Canada decided to exclude industry reports and stick to the science in the formation of their new dietary guidelines. What a concept! Major changes included a new emphasis on plant-based food intake, limiting junk, and the removal of the dairy food group.