Most of the articles a mom finds about mastitis mention frequency odds and lifestyle habits like tight-fitting bras and irregular nursing. There's usually a cursory mention of "poor nutrition" as a factor, but what this means isn't clearly defined. There's research which provides better answers.
For context, think about susceptibility. Some women never experience mastitis, no matter how much or little the baby nurses, how tightly their bra fits, how they sleep, or what they eat. Other women miss one nursing and have to hit the shower to relieve the pain.
What's the difference? Everyone has bacteria all over their skin all the time, and when milk from moms with mastitis is cultured for bacteria, there are usually several kinds of bacteria acting at once. Something that's normally not a problem has become a problem. Why?
The pathogens around us generally don't cause infection thanks to our "innate immune system", the non-specific immune factors in our blood, fluids, and tissues, which constantly scavenge for things that shouldn't be there. This is the first line of defense, and if a pathogen gets past this, the "adaptive immune system" is activated to mount a response.
The adaptive response is the one we notice as fever and pain, while the innate immune system goes unnoticed day after day while it spares us illnesses we don't know about.
Moms who are prone to mastitis and other infections likely have factors compromising their innate immunity. This could be an existing infection, stress, environmental chemicals, or nutrient deficiency. Addressing specific nutrient deficiencies is an easy first step.
In addition to the usual mouse models, there are other animals to show what nutrients are key. There's apparently far more research into nutritional prevention of mastitis in cows than we'll ever see in humans. It makes sense - Dairy is big business, and cows are easier to research since their lives are already managed with consistent parameters. (They also give milk on a regular schedule, and don't wear tight clothing.)
Vitamins A and E, and the minerals Calcium, Selenium, Copper, and Zinc, have all been studied for their roles in the immune system, particularly as it pertains to mastitis. For cows, this means checking that they eat all their nutrient-dense feed, even when they don't have a great appetite around calving. Sounds familiar. Lots of humans don't feel like eating much in the last few weeks of pregnancy, and may not eat as much as they would like in the first several weeks postpartum.
Besides taking the time to eat real food, the easiest way to get all of these nutrients and more is to keep taking your prenatal vitamin or your preferred high-quality multivitamin. EVERY DAY. And if you miss a day, take a little more the next day. The gap between sufficient and overdose is enormous; it won't hurt to double up now and then.
High Blood Sugar and High Insulin also inhibit immune function. If you're snacking on simple carbs and you're sleep-deprived (like most moms with a small baby), odds are your insulin and blood sugar are BOTH elevated. Don't restrict overall calories, because that's another stressor on the immune system and your body overall; instead, go for a better mix of protein, fiber, fat, and whole-food carbohydrates.
Lecithin is widely recommended for mastitis prevention, though no one seems quite sure how it works. (Not like that's a reason not to try it,) The most common line of thinking seems to be that it prevents plugged ducts by changing the fat profile and thus the viscosity of milk, and other factors may further contribute to its mastitis prevention powers. Lecithin contains Vitamins E and K, and essential fatty acids which are essential for cell membranes. It's been shown than lecithin boosts the immune system by increasing lymphocytes and macrophages. (1) While soy lecithin is of less concern than other soy products, if you'd prefer not to use soy, there are various other sources for lecithin. One nice benefit is that choline is an important nutrient for brain function and metabolism, and has a protective effect against fatty liver. Who doesn't need a little brain boost with a newborn?
Hope this is a quick and easy look at the bigger picture, and what simple steps you can take to prevent mastitis. Please share your favorite supplements and tips!