Nutrition and Breastfeeding

What Nursing Mothers Really Need to Know

One of the most common questions I hear from parents is, “Is my diet affecting my milk supply or the quality of my milk?” It’s a completely valid concern, especially in a world where nutrition advice is often contradictory and overwhelming. If you’re trying to do the best you can for your baby while also taking care of yourself, it makes sense to wonder how much weight your daily food choices carry. So let’s talk about it—without guilt, without diet culture noise, and with evidence-based clarity.

Your Diet and Milk Supply

The body is incredibly wise. Research continues to show that milk production is a highly protected function. In most cases, day-to-day fluctuations in your diet or water intake will not cause a sudden drop in milk supply. Some studies have even shown that slow and gradual weight loss while also prioritizing nourishment can also be possible without affecting milk production. However, persistent undernutrition, vitamin and mineral deficiencies, or chronic illness can absolutely affect supply over time.

That said, nourishing yourself well by eating enough and not skipping meals helps you feel better and recover more fully from birth. And when you feel better, you parent better. Meeting your daily calorie and protein needs is important not only for maintaining milk production but also for your energy, mood, and mental health.

Vitamin Content in Breast Milk

Here’s where your diet can make a measurable difference: the micronutrient composition of your milk. Levels of certain vitamins—such as vitamin A, D, B6, B12, choline, and iodine—can reflect your dietary intake. If you're deficient, your milk may also be lower in those nutrients.

Micronutrients That May Be Affected by Your Diet

Vitamin A: Critical for vision and immune health. Found in sweet potatoes, carrots, dark leafy greens, apricots, eggs, and fortified dairy products.

Vitamin D: Essential for calcium absorption and immune support. Sources include fatty fish, liver, egg yolks, and fortified foods—but most people still don’t get enough through diet and sunlight alone. Many lactating parents and infants benefit from a supplement.

Vitamin B6: Important for brain development and protein metabolism. Sources include bananas, chickpeas, fish, poultry, potatoes, and fortified cereals.

Vitamin B12: Vital for neurological function and red blood cell production. Found in animal products like meat, fish, eggs, dairy, and fortified foods. Supplementation is essential for vegan and vegetarian mothers.

Choline: A lesser-known but important nutrient for brain development. Found in eggs (especially the yolk), liver, meat, and some legumes.

Iodine: Required for healthy thyroid function and infant brain development. Found in dairy, seafood, and eggs. Many pregnant and lactating people in the U.S. don’t get enough.

Talk to your primary care provider about testing your vitamin levels, especially if you follow a restrictive diet or have a history of deficiency.

What Does “Eating Well” While Breastfeeding Actually Mean?

Forget the Pinterest-perfect meal plans. Supporting your body during lactation doesn’t have to be complicated, but it does require some intention. Here’s what matters most:

• Get Enough Protein: Aim for at least 30g of protein per meal and/or 100g of protein per day. Think eggs, meat, fish, beans, greek yogurt, tofu, and protein powders, if needed.

• Don’t Fear Healthy Fats: Your body needs fat for hormone production, milk synthesis, and brain health. The fatty-acid profile of your milk can also be affected by the types of fat you eat. Include foods like avocado, olive oil, nuts, chia, flax, and basil seeds, beef, fatty fish, and full-fat dairy.

• Balance Your Carbohydrates: Carbs are fuel, especially if you're up all night nursing. Focus on whole-food sources like fruits and vegetables.

• Stay Hydrated: Hydration doesn't directly boost milk supply, but dehydration can make you feel tired and sluggish. Drink to thirst, and keep a water bottle nearby during feeds.

• Eat the Rainbow: A variety of fruits and vegetables of different colors ensures you’re getting a broad spectrum of vitamins, minerals, and antioxidants.

How Many Calories Do You Need?

On average, lactation increases your energy needs by 300–500 extra calories per day. But this isn’t a one-size-fits-all rule. Your individual needs depend on your size, metabolism, activity level, and how much milk you’re producing. If you're unsure, consider working with a registered dietitian to calculate your TDEE (Total Daily Energy Expenditure).

What Foods Should Be Avoided?

One of the most persistent breastfeeding myths is that mothers need to avoid spicy foods, garlic, onions, cruciferous vegetables like broccoli, or common allergens. In reality, unless your baby is showing specific symptoms of intolerance (like blood in the stool, rash, severe reflux, or persistent unexplained fussiness), there is no need to eliminate these foods. In fact, one study showed that babies preferred the breast milk of mothers after eating garlic!

That said, there are a few foods and substances you should be cautious about:

• High-Mercury Fish: Avoid shark, swordfish, king mackerel, orange roughy, and tilefish. Limit albacore tuna to 6 oz per week. Safer seafood options include salmon, sardines, tilapia, cod, shrimp, scallops, and canned light tuna.

• Alcohol: Occasional, limited alcohol consumption of one beer or glass of wine is generally considered compatible with breastfeeding. Just be mindful of timing—alcohol peaks in milk about 30–60 minutes after drinking and then leaves the breast milk after you’re no longer feeling buzzed. Do not binge drink while breastfeeding.

• Caffeine: Up to 300 mg per day is typically safe. Watch for signs of sensitivity in your baby like jitteriness, fussiness, or poor sleep.

Breast milk is an incredibly adaptive, protective fluid—your body will prioritize making high-quality milk even when your diet isn’t perfect. But that doesn’t mean your nutrition doesn’t matter. Supporting your own health through adequate nutrition will help you feel more energized, help prevent postpartum depletion, and support long-term well-being. You deserve to feel nourished, not depleted. So eat the foods that make you feel strong, reach out for support when you need it, and let go of the pressure to be perfect.

References:

Allen, J. C., & Hector, D. J. (2005). Benefits of breastfeeding. NSW Public Health Bulletin, 16(3-4), 42-46. DOI: 10.1071/NB05013.

Andreas, N. J., Kampmann, B., & Le-Doare, K. M. (2015). Human breast milk: A review on its composition and bioactivity. Early human development, 91(11), 629-635. DOI: 10.1016/j.earlhumdev.2015.08.013.

Munblit, D., Peroni, D. G., Boix-Amorós, A., Hsu, P. S., Van't Land, B., Gay, M. C. L., ... & Warner, J. O. (2017). Human milk and allergic diseases: an unsolved puzzle. Nutrients, 9(8), 894. DOI: 10.3390/nu9080894.

Rasmussen B, Ennis M, Pencharz P, Ball R, Courtney-martin G, Elango R. Protein Requirements of Healthy Lactating Women Are Higher Than the Current Recommendations. Curr Dev Nutr. 2020 May 29;4(Suppl 2):653. doi: 10.1093/cdn/nzaa049_046.

Allen, L.H. (2012). B Vitamins in Breast Milk: Relative Importance of Maternal Status and Intake, and Effects on Infant Status and Function. Advances in Nutrition, 3(3), 362-369. https://doi.org/10.3945/an.111.001172

National Institutes of Health Office of Dietary Supplements. Vitamin D Fact Sheet for Health Professionals. https://ods.od.nih.gov/factsheets/VitaminD-HealthProfessional/

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