Do I need to Avoid Dairy After Prostate Cancer?

By Meredy Birdi, Oncology Dietitian and Nutritional Therapist

“Should I avoid dairy after prostate cancer?”

If you’ve been looking into diet and prostate cancer, you may have come across information suggesting that milk or dairy foods might increase risk. Understandably, this can leave people feeling unsure about what to do with dairy after a prostate cancer diagnosis.

To make sense of this, it helps to look at the overall body of evidence rather than focusing on individual studies.

This article explores what the research shows, why findings can sometimes sound more concerning than they are, and what this means in practice for people trying to make food choices after a prostate cancer diagnosis.

Why the dairy question comes up

Part of the reason dairy comes up so often in conversations about prostate cancer is that some studies have reported associations between dairy intake and prostate cancer.

When findings from individual studies are shared through headlines, social media, articles or online discussions without context, they can sound more certain than they are.

What the studies are looking at

Not all studies are looking at the same populations or asking the same questions.

Some follow people in the general population to explore links between diet and prostate cancer or prostate cancer mortality. Others focus on men who have already been diagnosed, looking at outcomes such as recurrence, disease progression, or prostate cancer mortality.

Because of this, findings from one type of study cannot always be applied or interpreted in the same way as another.

Most research in this area is observational

Most of the research we have on diet and prostate cancer is observational.

In these studies, researchers follow large groups of people over time. Participants report what they typically eat, and researchers track health outcomes. This helps identify patterns, but it has limitations.

Dietary intake is usually self-reported, which relies on memory and estimation. Sometimes it's only collected once at the start of a study, even though participants may be followed for many years. People’s diets can change over time, so that single snapshot may not reflect what someone is eating later on.

People who eat certain foods may also differ in other ways - such as body weight, physical activity, smoking, alcohol intake, or overall diet. Researchers try to adjust for these differences, but it’s impossible to account for everything perfectly.

For these reasons, observational studies can show associations, but they cannot prove that a particular food directly caused a health outcome.

Association does not mean cause

When two things appear together in research, it doesn’t necessarily mean one caused the other.

A simple example to help illustrate this is that when people are carrying umbrellas, their feet are often wet. Umbrellas and wet feet appear together. But umbrellas do not cause wet feet. The rain is the underlying factor explaining both.

Nutrition research can work in a similar way, where two things may occur together without one directly causing the other.

Why scientists look for patterns across many studies

Because individual studies all have limitations, recommendations are based on the overall body of evidence rather than any single piece of research.

If a dietary factor has a strong effect, similar findings tend to appear across multiple studies. When findings vary between studies, it suggests any effect may be small or influenced by other factors.

Another important consideration is the population being studied. Dietary patterns, portion sizes and food production practices can vary between countries and cultures, so findings from one population do not always translate perfectly to another.

What the research shows about dairy and prostate cancer

In short, current evidence does not show a clear or consistent link between dairy intake and prostate cancer.

Looking specifically at men who have already been diagnosed with prostate cancer, some observational studies have reported associations between high intakes of full-fat dairy and less favourable prostate cancer outcomes. However, the evidence remains limited and inconsistent, and does not support broad avoidance of dairy foods. Total dairy and low-fat dairy show no clear association with outcomes.

What about calcium?

Another question that often comes up is whether calcium, rather than dairy foods specifically, might be the relevant factor.

Organisations such as the World Cancer Research Fund and American Institute for Cancer Research review the totality of the evidence. In these reviews, the evidence linking higher intakes of calcium, often from dairy foods, with prostate cancer risk is classified as "limited - suggestive." This means the findings are not strong or consistent enough to support firm conclusions.

Their guidance focuses on overall dietary patterns, with moderate dairy intake able to fit within a healthy diet.

Calcium is also important for bone health, particularly for men receiving treatments such as androgen deprivation therapy.

Putting risk statistics into perspective

When research papers report increases in risk, the numbers can sound worrying at first.

Often, these figures describe relative risk, rather than the actual number of people affected. For example, if 4 out of 1000 people experience an outcome, a 50% increase in relative risk would raise that to around 6 out of 1000.

So while the percentage sounds large, the difference in real terms may still be quite small. This can help put some of the more alarming headlines into perspective.

What seems to matter most for long-term health after prostate cancer?

When we step back and look at the body of evidence, what we see is that outcomes after a prostate cancer diagnosis are influenced far more by overall dietary pattern and lifestyle than by any single food.

This includes:

• Maintaining a healthy body weight

• Regular physical activity

• A plant-rich, fibre-rich diet

• Supporting heart and metabolic health through balanced eating

What about dairy after prostate cancer?

Dairy foods don't need to be avoided. For people who are eating well and maintaining their weight, a balanced approach might include:

• Including dairy in moderate amounts

• Choosing lower-fat options more often

• If you enjoy whole milk, having it more occasionally rather than regularly

If you are struggling with appetite or weight loss, your nutritional priorities may be different. In those situations, maintaining your weight and getting enough nourishment often become the focus, and higher-energy options can be helpful.

If you choose to reduce or avoid dairy, that’s fine. You can meet your nutritional needs in other ways. This is here to support you if you’re including dairy but feeling unsure about it.

In summary

The research around dairy and prostate cancer can feel confusing when individual studies are viewed in isolation.

Current evidence does not support broad avoidance of dairy foods after a prostate cancer diagnosis. If you enjoy dairy foods, moderate amounts can fit within a healthy dietary pattern.

What appears to matter more is the overall pattern of diet and lifestyle - including maintaining a healthy body weight, staying physically active, and following a balanced, plant-rich diet.

Frequently Asked Questions

Should men with prostate cancer avoid dairy?

No, you don’t have to. Current evidence does not support broad avoidance of dairy foods after a prostate cancer diagnosis.

If you enjoy dairy foods, moderate amounts can fit within a healthy dietary pattern.

Does drinking milk increase prostate cancer risk?

Some studies have raised questions about whether higher intakes of dairy may be linked to prostate cancer risk. However, when the overall body of evidence is considered, the findings remain limited and inconsistent and are not strong enough to support recommendations to avoid dairy foods.

What appears to matter far more is the overall pattern of diet and lifestyle, including maintaining a healthy body weight, staying physically active, and following a balanced, plant-rich diet.

This doesn't need to be an all-or-nothing decision. For most people, moderate amounts of dairy can fit within a healthy diet.

Does the type of dairy you choose matter?

If you’re eating well and maintaining your weight, it helps to think about what a food is contributing to your diet and how often it’s part of your usual way of eating.

Foods like natural yoghurt or kefir can provide protein and beneficial bacteria, and can be worth including more regularly. There’s also space for foods like cheese as part of a balanced diet.

Dairy foods with added sugars or more heavily processed options - such as sweetened yoghurts, desserts or shop-bought milk-based drinks - are usually better kept as an occasional choice rather than something you rely on day to day.

As with many areas of nutrition, the overall pattern matters more than any single food.

References and further reading

• World Cancer Research Fund. https://www.wcrf.org/preventing-cancer/cancer-types/prostate-cancer/

• American Institute for Cancer Research. https://www.aicr.org/cancer-survival/cancer/prostate-cancer/

• Langlais CS, et al. https://link.springer.com/article/10.1007/s11912-021-01017-xCurr Oncol Rep. 2021 Mar 10;23(3):37. doi: 10.1007/s11912-021-01017-x. PMID: 33689041

This blog is for general information only and is not a substitute for individual medical or dietetic advice.