Breast milk is incredibly nutritious. In fact, it provides most of the nutrients that your baby needs for the first 6 months of life (1, 2). 

While the composition of breast milk is tightly regulated by your body, research has shown that what you eat does have some effect on the contents of breast milk (3, 4). 

In general, no foods are off-limits. Instead, women are recommended to eat a balanced, varied diet. Still, there are some foods and beverages that you may want to limit while breastfeeding. 

Here are 5 foods to limit or avoid while breastfeeding, as well as tips for how to tell if your diet is affecting your baby. 

1. Fish high in mercury 

Fish is a great source of docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) — two types of omega-3 fatty acids that are important for brain development in infants, yet can be hard to find in other foods (5). 

However, some fish and seafood can also be high in mercury, a metal that can be toxic — especially in infants and kids, who are more sensitive to mercury poisoning (6, 7). 

Acute exposure to high levels of mercury can permanently affect your infant’s central nervous system. As a result, they may have delays or impairments in (6, 8): 

  • cognition
  • fine motor skills
  • speech and language development
  • visual-spatial awareness

Therefore, fish that are high in mercury should be avoided while breastfeeding. Examples include (9): 

  • bigeye tuna 
  • king mackerel
  • marlin
  • orange roughy  
  • shark
  • swordfish
  • tilefish

To ensure adequate omega-3 intake while reducing the risk of mercury poisoning, mothers who breastfeed are recommended to avoid high mercury fish and instead consume 8–12 ounces (225–340 grams) of low mercury fish per week (9).

summary

Due to concerns over mercury poisoning in infants, women who are breastfeeding should avoid fish that are high in mercury, such as shark, swordfish, and bigeye tuna.

2. Some herbal supplements

The use of herbs and spices like cumin or basil to season food is considered safe during breastfeeding. 

However, when it comes to herbal supplements and teas, there are some concerns about safety, as there’s a lack of research in women who are breastfeeding (10, 11).

Additionally, because herbal supplements aren’t regulated by the Food and Drug Administration (FDA) in the United States, there’s also the potential for these supplements to be contaminated with potentially dangerous heavy metals (10, 11). 

While many women try supplements to help increase milk supply, there’s overall limited evidence on their effectiveness, with most studies finding no difference in breast milk production compared with a placebo (12).

It’s best to speak with your healthcare provider before trying out a supplement.

summary

As most herbal supplements haven’t been evaluated for their safety during breastfeeding, it’s recommended to talk with your healthcare provider before using any supplements or herbal teas. 

3. Alcohol

According to the Centers for Disease Control and Prevention (CDC), abstaining from alcohol is the safest option during breastfeeding. However, an occasional drink is likely safe, as long as you’re cautious about the amount and timing (13). 

How much alcohol your baby can get from breast milk depends on how much alcohol you consumed and when you consumed it. Research shows that the amount of alcohol in breast milk peaks 30–60 minutes after your last drink (14). 

Plus, alcohol can remain in your system for up to 2–3 hours. This is just for one drink — the more alcohol you have, the longer it can take to be cleared from your system (14).

As a result, the CDC recommends limiting alcohol to just one standard drink per day and waiting at least 2 hours after that drink to breastfeed (13).

One standard drink is equivalent to (15):

  • 12 ounces (355 mL) of beer
  • 5 ounces (125 mL) of wine
  • 1.5 ounces (45 mL) of hard alcohol 

High levels of alcohol consumption have been shown to reduce breast milk output by 20%. (14)

Moreover, frequent, excessive alcohol intake during breastfeeding has been linked to an increased risk of disrupted sleep patterns, delay in psychomotor skills, and even cognitive delay later in life (13, 14, 16, 17). 

summary

Women who are breastfeeding are recommended to limit alcohol to one drink or less per day and to wait at least 2 hours before breastfeeding. Frequent and excessive alcohol intake can reduce milk production and have serious effects on your baby.

4. Caffeine

Coffee, soda, tea, and chocolate are common sources of caffeine. When you consume them, some of that caffeine can end up in your breast milk (18, 19). 

This can be problematic, as babies have a hard time breaking down and getting rid of caffeine. As a result, large amounts of caffeine over time could accumulate in your baby’s system, causing irritability and trouble sleeping (19, 20).

According to the CDC, mothers who are breastfeeding are recommended to consume no more than 300 mg of caffeine per day, which is equivalent to two or three cups of coffee (18). 

As energy drinks often contain added vitamins and herbs, in addition to high amounts of caffeine, women who are breastfeeding are recommended to avoid these products unless otherwise approved by a trusted healthcare provider (21). 

summary

During breastfeeding, women are recommended to limit caffeine intake to 300 mg per day or less to prevent irritability and disrupted sleep patterns in your infant. 

5. Highly processed foods

To meet the increased nutrient demands of breastfeeding, it’s incredibly important that you eat a healthy, balanced diet (22). 

As highly processed foods are generally high in calories, unhealthy fats, and added sugars, yet low in fiber, vitamins, and minerals, it’s recommended to limit their intake as much as possible. 

Early research has also suggested that a mother’s diet while breastfeeding may influence her child’s diet later in life (23, 24, 25). 

Specifically, animal studies have found that flavors infants are exposed to through breast milk can influence their food preferences as they grow up (26). 

One study observed that rats born to mothers with a high junk food diet were significantly more likely to prefer high fat, high sugar foods than those whose mothers had a balanced, healthy diet (27).

While more research is needed in humans, there’s a concern that frequent exposure to fatty, sugary foods as an infant may lead to less healthy eating habits and obesity as the child ages.

summary

As highly processed foods are generally low in essential nutrients and may affect your child’s food preferences later in life, it’s recommended that breastfeeding moms limit their intake of foods that are high in added sugars and processed fats. 

Other considerations

As flavors of foods and beverages end up in your breast milk, some moms find that strongly flavored foods like onion, garlic, or spices cause their babies to refuse to feed or become fussy after eating (28, 29). 

While there’s no evidence to suggest that all mothers should avoid strongly flavored foods, if you notice changes in your baby’s feedings, it’s important to talk with your dietitian or pediatrician about eliminating certain foods or spices from your diet (29, 30). 

Other potential food groups that may need to be avoided during breastfeeding include cow’s milk and soy products

Approximately 0.5–2% of breastfed infants may be allergic to cow’s milk protein from their mother’s milk, while 0.25% may be allergic to soy protein (31, 32, 33, 34). 

If your pediatrician suspects that your baby may have an allergy to milk or soy, it’s recommended to exclude all cow’s milk or soy protein from your diet for 2–4 weeks if you want to continue breastfeeding (35). 

summary

Some babies may be more sensitive to strongly flavored foods or have an allergy to cow’s milk or soy protein. In these cases, it’s important to talk with your pediatrician before eliminating foods from your diet. 

How to tell if your diet is affecting your baby

Every baby is different. However, there are some common signs that your diet may be affecting your baby, including (36, 37): 

  • eczema
  • bloody stools
  • vomiting
  • diarrhea
  • hives
  • constipation
  • wheezing 
  • congestion
  • abnormal fussiness
  • excessive gas 
  • anaphylaxis — while rare, it’s important to seek immediate medical attention

If your baby exhibits any of these symptoms, it could be a sign that your baby is allergic or intolerant to a food in your diet. It’s important to make an appointment with your pediatrician, as they can work with you to help identify the problematic food.

For some food allergies, you may be instructed to cut out any suspected allergens for 2–4 weeks to see if symptoms subside. 

Keep in mind that though your baby may have intolerances or allergies as an infant, they may still be able to tolerate those foods as they get older. Consult your pediatrician before adding foods back into your diet or your child’s (38).

summary

Symptoms like eczema, bloody stools, diarrhea, and congestion can indicate a food allergy or intolerance in your infant. It’s important to work with your pediatrician to identify which food(s) may be affecting your baby. 

The bottom line

Breastfeeding provides essential nutrients for your growing infant. 

While most foods that were off-limits during pregnancy are back on the menu, there are some foods and beverages that may not be tolerated by or have negative effects on your baby. 

While it’s recommended to completely avoid fish high in mercury and some herbal supplements, foods like alcohol, caffeine, and highly processed products can still be consumed but in limited amounts. 

If your baby has symptoms like eczema or bloody stools, it may be due to something in your diet. It’s important to share your concerns with your pediatrician before making any sudden dietary changes.