According to research reviewed by Gram, maternal diet, especially healthy fats, is the primary factor affecting breast milk composition. Some emerging evidence suggests cannabis use may alter fat and protein levels in milk, but current research is too limited and inconsistent to draw firm conclusions. Scientists cannot yet separate cannabis’s direct effects from related factors like poor nutrition and poverty, which also change milk composition. More rigorous studies are needed before healthcare providers can give clear guidance on cannabis use while breastfeeding.
A new review of scientific studies examined whether smoking cannabis while breastfeeding changes the nutrients and protective substances in breast milk. Researchers found that a mother’s diet is the biggest factor affecting milk composition, especially the healthy fats. Some early evidence suggests cannabis use might change fat and protein levels in milk, but scientists aren’t sure if cannabis itself causes these changes or if it’s related to diet and poverty. The research is still too limited to give clear answers, and doctors say more studies are needed before we understand how cannabis affects babies through breast milk.
Key Statistics
A 2026 narrative review in the Journal of Human Lactation found that maternal diet is the key determinant of breast milk composition, particularly for fatty acids, while evidence linking cannabis use to milk changes remains sparse and inconclusive.
According to a 2026 review of breastfeeding research, some studies suggest cannabis consumption may be associated with alterations in fat and protein concentrations and immune components like Secretory Immunoglobulin A, but these associations may be confounded by dietary patterns and socioeconomic disadvantage.
A 2026 analysis of cannabis and breast milk research identified that socioeconomic disadvantages influencing maternal nutrition are key confounding variables that future studies must control for to clarify cannabis’s direct effects on infant health outcomes.
The Quick Take
- What they studied: Whether smoking cannabis while breastfeeding changes the nutrients, fats, proteins, and immune-boosting substances in breast milk
- Who participated: This was a review of existing studies, not a new experiment. Researchers looked at published scientific papers about breastfeeding, maternal diet, and cannabis use
- Key finding: Maternal diet is the strongest factor affecting breast milk composition. Some studies suggest cannabis might change fat and protein levels, but the evidence is weak and unclear because other factors like poverty and poor nutrition might be responsible
- What it means for you: If you’re breastfeeding and use cannabis, current science doesn’t provide clear answers about safety. Talk to your doctor before using cannabis while nursing. A healthy diet matters more for milk quality than any single substance
The Research Details
This was a narrative review, which means researchers read through published scientific papers on the topic and summarized what they found. They searched for studies about breast milk composition, what mothers eat, and cannabis use. Unlike a strict scientific study, a narrative review doesn’t follow rigid rules about which studies to include, researchers use their judgment to pick the most relevant ones.
The researchers looked at how breast milk changes based on what mothers eat and whether they use cannabis. They paid special attention to fats, proteins, and immune-fighting substances called antibodies that protect babies from infection. They also noted that poverty, poor nutrition, and other life stressors often go hand-in-hand with cannabis use, which makes it hard to know what’s actually causing changes in milk.
A narrative review is useful when a topic is new or hasn’t been studied much yet. It helps scientists understand what we know and what we still need to learn. In this case, there aren’t many high-quality studies on cannabis and breast milk, so a review that pulls together all available information is the right approach. This type of study is honest about limitations and helps identify what future research should focus on
This review is transparent about its limitations. The authors admit the evidence is sparse and inconsistent, meaning different studies show different results. They correctly point out that we can’t tell if cannabis directly changes milk or if other factors (like diet and poverty) are responsible. The review doesn’t make strong claims beyond what the evidence supports, which is a sign of good scientific thinking
What the Results Show
Maternal diet is the strongest factor affecting breast milk composition, particularly the types of fats in milk. When mothers eat more healthy fats, their milk contains more healthy fats. This relationship is well-established and consistent across studies.
Regarding cannabis, the evidence is much weaker. Some studies suggest that cannabis use might be associated with changes in fat and protein levels in breast milk, and possibly with lower levels of Secretory Immunoglobulin A (SIgA), which is an antibody that helps protect babies from infections. However, these associations are not clear-cut.
The biggest problem is that cannabis use often occurs alongside other factors that also change breast milk composition. Mothers who use cannabis are more likely to have poor nutrition, experience poverty, or face other health challenges. These factors independently affect milk quality, making it impossible to know if cannabis itself is the culprit or if it’s these other circumstances.
The review identified that socioeconomic disadvantage (poverty, limited access to healthy food) is a major factor affecting breast milk composition. Mothers facing financial hardship often have less nutritious diets, which directly impacts their milk. The underlying biological mechanisms, how cannabis would actually change milk composition, remain poorly understood and haven’t been well-studied in humans
This review adds to a growing body of research showing that breast milk is dynamic and changes based on maternal health and environment. Previous research firmly established that diet matters for milk composition. This review is one of the first to systematically look at cannabis specifically, but it confirms what scientists suspected: the evidence is too limited to draw conclusions. The review emphasizes that future studies need better design to separate cannabis effects from diet and poverty effects
The biggest limitation is that very few studies exist on this topic, and the ones that do exist have mixed results. Most studies weren’t designed specifically to test cannabis’s effects on milk, they looked at cannabis use as one factor among many. The review couldn’t find studies that carefully controlled for diet and socioeconomic status while studying cannabis. Additionally, this is a narrative review, not a systematic review with strict rules, so some bias in which studies were selected is possible. The authors couldn’t calculate overall statistics because the studies were too different from each other
The Bottom Line
Based on current evidence, health organizations recommend avoiding cannabis use while breastfeeding, though the research is still developing. The evidence is not strong enough to say exactly how much risk exists, but the precautionary approach is to avoid it. If you use cannabis and are breastfeeding, discuss this with your doctor or lactation consultant. Focus on eating a nutritious diet with healthy fats, which has clear evidence of improving milk quality
Breastfeeding mothers considering cannabis use should care about this research. Healthcare providers advising pregnant and nursing mothers should be aware that evidence is limited. Researchers studying breast milk composition should pay attention to the call for better-designed studies. People making policy decisions about cannabis and pregnancy/nursing should know that current evidence is insufficient for clear guidance
If you improve your diet while breastfeeding, milk composition can change within days to weeks. If you stop using cannabis, any potential effects would likely reverse over a similar timeframe, though this hasn’t been specifically studied. Long-term effects on infant health from cannabis exposure through breast milk are unknown and require future research
Frequently Asked Questions
Is it safe to smoke cannabis while breastfeeding?
Current evidence is insufficient to determine safety. A 2026 review found that while some studies suggest cannabis may alter milk composition, researchers cannot separate cannabis effects from diet and poverty factors. Health organizations recommend avoiding cannabis while nursing until more research clarifies risks to infants.
Does cannabis pass into breast milk?
Cannabis compounds do transfer into breast milk, but a 2026 review found limited research on how much this affects milk composition or infant health. The review emphasizes that maternal diet and socioeconomic factors have clearer, stronger effects on milk quality than cannabis use.
What affects breast milk composition the most?
According to a 2026 narrative review, maternal diet is the strongest determinant of breast milk composition, especially the types and amounts of healthy fats mothers consume. Socioeconomic status and overall maternal health also significantly influence milk nutrients and immune-protective substances.
Can I improve my breast milk quality if I use cannabis?
Focusing on a nutrient-dense diet with healthy fats will improve milk composition regardless of cannabis use. A 2026 review confirms that dietary changes have clear, measurable effects on breast milk. Discuss cannabis use with your healthcare provider to understand individual risks and benefits.
What should I do if I’m breastfeeding and use cannabis?
Talk to your doctor or lactation consultant before continuing cannabis use while nursing. A 2026 review found insufficient evidence to give definitive guidance, but health organizations recommend avoiding it as a precaution. Your healthcare provider can discuss individual circumstances and help you make informed decisions.
Want to Apply This Research?
- Track daily dietary fat intake (sources like avocados, nuts, olive oil, fatty fish) and correlate with any changes you notice in breastfeeding comfort or infant digestion. Log weekly cannabis use if applicable, along with dietary quality scores, to identify patterns
- Use the app to plan daily meals emphasizing healthy fats and complete proteins. Set reminders to eat nutrient-dense foods at each meal. If using cannabis, track use patterns and discuss trends with your healthcare provider during check-ins
- Monitor infant growth metrics (weight gain, feeding frequency) monthly and note any correlations with maternal diet changes. Track your own nutritional intake weekly using the app’s food logging feature. Schedule quarterly reviews with your healthcare provider to discuss any concerns about breastfeeding quality or infant development
This article summarizes a scientific review and should not replace professional medical advice. If you are pregnant, breastfeeding, or considering cannabis use while nursing, consult with your obstetrician, pediatrician, or lactation consultant before making any decisions. Current evidence on cannabis and breast milk is limited, and healthcare providers may recommend avoiding cannabis use while nursing as a precautionary measure. Individual circumstances vary, and personalized medical guidance is essential. This information is for educational purposes only and does not constitute medical advice.
This research translation is published by Gram Research, the science division of Gram, an AI-powered nutrition tracking app.
