Crying Over Spilt Milk?
If you’re interested in integrative medicine, whether reading blogs or seeing practitioners, you’ve likely come across the idea that to lower inflammation and manage inflammatory conditions, many of which include mental health conditions, your diet must be free of both gluten and dairy-containing foods.
We’ve previously covered the role of gluten in psychological wellbeing, particularly the role of coeliac disease.
This article will look at the evidence for a dairy-free diet to improve psychological well-being. Removing dairy from your diet can be challenging, particularly in a society where dairy is everywhere, so this article aims to shed light on when and for whom this dietary change is worth exploring. We’ll look at
What is it about dairy that might be problematic for certain people?
Food-derived opiate theory
Immunoglobulin theory
Is there any evidence that a dairy-free diet will lower risks or improve mental well-being? And for whom?
The makeup of milk
The component of dairy that’s most relevant to mental well-being is the protein component (as opposed to the carbohydrate component, which is lactose). Of dairy protein, about 80% is casein, with the remaining 20% whey. Within the casein group, there are 3 main types - alpha, beta and kapha. Within the beta group, we have specific proteins called A1 and A2.
You’ve probably come across the different types of dairy products based on A1 and A2 milk. A1 is the most common form found in commercial cows dairy products - it’s traced back to a genetic mutation thought to have happened thousands of years ago in European cows, and dominates the market in Australia and New Zealand. A2-only products have entered in the last few years alongside rising interest in the effect of dairy on human health. Sheep, goat and human milk is A2 protein - although some cows milk can be A2 as well, if the specific breed of cow used is an A2-producing breed (Jersey and Guernsey cows are examples).
A1 and A2 casein have different amino acid sequences and as a result, are digested differently by humans - A1 digestion generates large amounts of a peptide called beta-caso-morphine 7 (BCM-7). BCM-7 can interact with certain receptors in humans and cause biochemical reactions. It's these interactions with our cell receptors that lead to its biological effects, including those on the brain.
Dairy on the brain - two key theories for how it may affect mental health
1. Food-derived opiates from dairy
Evidence from both animal and human studies shows that after consumption of casein, the dietary peptide BCM-7 is capable of crossing from the gut into the bloodstream. It's also been found in the cerebrospinal fluid of the brain, indicating it's able to cross the blood-brain barrier.
Once in the brain, it engages most strongly with opiate receptors, which are also found in the human gut (among other places). Opiates, like the pain drug morphine, bind to these receptors and have a set of reasonably well-defined effects. They:
Inhibit or reduce the calming neurotransmitter GABA
Increase dopamine levels by reducing its breakdown. Dopamine is an excitatory neurotransmitter, which whilst helpful and essential for our mental and physical health, can at increased levels lead to increased oxidative stress in the brain (increased damage to brain cells)
May stimulate an inflammatory cytokine cascade in the brain (a central hypothesis of modern mental health research)
Slow down peristalsis in the gut - this usually presents as constipation or slow transit time after drugs like morphine. An effect many people experience with dairy also.
stimulate mucus production, which is why some people can feel snotty and congested after dairy.
When scientists injected BCM-7 into rats, they exhibited behaviour consistent with excessive dopamine - they became erratic, explosive and aggressive, followed by social withdrawal. Opiate blockers stopped the reaction, indicating the reaction was due to the engagement of BCM-7 with opiate receptors.
2. Immune reactions to dietary peptides
In addition to opiate-like effects from A1 beta-casein, dairy can stimulate an inflammatory reaction by the creation of antibodies to dairy proteins such as casein.
Antibodies to food are made by our immune system when a food protein moves through the intestinal wall and into the bloodstream - this intestinal permeability is commonly referred to as “leaky gut”. Antibodies made to foods are mostly of the IgG and IgA classes - this is different from the classic “allergy” that is an IgE response.
Crucially, not everybody makes IgG/IgA antibodies to food proteins when they are consumed. In the biggest study on this topic of almost 7000 people, about 50% of the population didn’t make any IgG to common foods despite eating them. Within the other 50%, IgG levels ranged from low to high. Importantly, not everyone who ate dairy made IgG - about 1 in 5 people who consumed it made an IgG response.
So what is different about these approximately 1 in 5 individuals that make antibodies to dairy? IgG antibodies tell us two things:
the person consumes dairy
they have intestinal permeability - the dairy proteins have breached the intestinal wall and made their way into the bloodstream. This person has a degree of “leaky gut”.
People who form antigen-antibody complexes to food and continue to eat them have the potential to further disrupt the intestinal barrier and stimulate an inflammatory response. Inflammatory responses affecting the central nervous system are a key hypothesis for depression and other mental health conditions, which has led scientists to look for connections linking the two.
Who’s at risk?
Antibodies made to dairy protein are higher in certain groups with mental health diagnoses than in the healthy population. The proportion making antibodies to dairy in the general population is approximately 1 in 5, whilst this ratio increases to around 1 in 2 in those diagnosed with schizophrenia, bipolar disorder or autism.
Furthermore, when the level of antibodies is measured in the brain, patients with schizophrenia were found to have antibodies in their cerebrospinal fluid, suggesting not just a leaky gut, but also a leaky brain.
Similarly, dietary opiates like BCM-7 measured in urine, are found in people diagnosed with autism, schizophrenia and postpartum psychosis, but not in the healthy control population. However, only a subset of people with autism, schizophrenia and postpartum psychosis make these higher levels - approximately 20% of this group. Once again, these within-group differences hint at the possibility of individual gut permeability playing a possible role.
What about depression and anxiety?
The connection between dietary opiates and antibodies to dairy in people with depression is much less clear-cut - there wasn’t the strong correlation across multiple studies seen in the other patient groups. There is some research to suggest that overall IgG responses to foods are elevated in depressed groups but more research is needed.
Deakin University is running a clinical trial comparing the effects of A1 versus A2 dairy on psychological distress in women. It includes dairy’s effect on gut health, sleep patterns and overall quality of life. This is an exciting development because it casts a wider net on mental wellbeing than the studies done so far, and may shed further light.
So, should I give up dairy?
If you were seeking a clear-cut answer to this question, by now you’ll know there isn’t one - yet!
However, we do have some clues from the research as to who might benefit from a dairy-free diet as part of a wider mental wellbeing plan:
Anyone with a diagnosis of schizophrenia, bipolar disorder or autism may like to consider the role of dietary opiates such as BCM-7 and food antibodies on their mental well-being. Options are to:
test for IgG/IgA antibodies to foods - this is available from many trained integrative clinicians and can provide a more definitive answer as to whether dairy elimination is required (remember only a subset of patients made antibodies to dairy)
work out whether you are in the group affected by dietary opiates from A1 dairy is less clear-cut, but some clinical clues can be seen in those who experience opiate-like effects after dairy:
~ Constipation or a slow-transit timeSnotty or congested after dairy foods
~ A high-dopamine picture - feeling aggressive or erratic with excess energy; possibly a tendency toward addiction. Or feeling "addicted" to dairy itself.
~ Obvious gut issues like IBS, coeliac disease or inflammatory bowel disease that may indicate a leaky gut - the leakier your gut, the more BCM-7 you're likely to absorb (as well as an increased potential for antibody production)
We have some evidence that eliminating foods with opiate-like effects (gluten and dairy being the most common) can reduce high levels of urinary opiates, with at least 28 weeks of elimination required to maximise results. It's definitely not something you can do in two weeks, which is why so many of the studies looking at this have failed to show a strong relationship. Conclusive evidence for improved mental health is not there yet, although positive case studies abound in the literature, especially in the schizophrenic populations.
From my clinical experience, people who have a problem with dairy will often notice a difference within about 4-8 weeks of a strict dairy-free diet. You’d want to see an improvement in your target symptoms with the elimination of a suspicious food, with symptoms returning once you added it back into your diet. This can help confirm if a food is problematic for you. This can be a tricky process to monitor so seeking out the help of a nutritionally aware clinician may be useful.
Remember A1 dairy drives much of the production of beta-casomorphin 7, so when re-introducing dairy after a trial elimination, A2 sources like goat and sheep products are the best to re-introduce first. The A1/A2 dairy trial may tell us more about the differences between A1 and A2 on psychological wellbeing.
Summing up
How can a food that is tolerated by many, be associated with increased risk in certain mental health populations? Once again, the clues lead us back to the gut and digestive process.
The leakier your gut, the greater the potential uptake of BCM-7, and the more chance you have of making antibodies to dietary proteins when they breach the intestinal lining. Both of these processes are capable of stimulating an inflammatory cascade, that for some, may extend to inflammation in the brain and central nervous system.
The full impacts of dairy on mental well-being are far from being all worked out, but the science is slowly forming a picture, with individual differences in gut health once again front and centre. For more on the connection between gut health and mental well-being, this article is a great introduction to the gut-brain connection.
