But there is some evidence showing that diet has an influence on milk production, as quoted from Lifestrong as following:
Diet to Increase supply of breast milk
1. Healthy eating
A pregnant woman should eat more than normal women to get enough energy for milk production. Women who are breastfeeding need about 500 extra calories each day. Pregnant women should also eat a variety of foods, as well as vitamin supplements, for a variety of nutrients needed by infants. Pregnant women should get at least three proteins and five servings of calcium every day, and eating foods rich in iron. Some foods that may be the top choice among others: green leafy vegetables, whole grains, fresh fruits, fish rich in omega three fats and low fat dairy products.
In addition to eating a variety of healthy foods, women who are breastfeeding should drink plenty of fluids. Besides water, you also can meet the needs of the body fluids of pure fruit juice, and low-fat milk to help increase milk supply. Breastfeeding mothers should get at least 8 glasses of fluid each day, preferably without caffeine. You also can try herbal teas that are designed to stimulate milk production.
Although most women produce enough milk for the baby, even if they are not good nutrition, but a poor diet can affect the quality of their milk. This will certainly affect the intake of nutrients needed by your baby. There are certain foods that can increase milk supply. These include, oatmeal, garlic and ginger. If your milk supply is low, try eating oatmeal for breakfast every day, and add a bit more spice to your diet.
Besides food, there are several dietary supplements that are marketed for nursing mothers, which is claimed to increase milk supply. Although there are few scientific studies that tested the effectiveness of these supplements, but many nursing mothers who reported the successful use of these herbal supplements. The experts of the Newman Breastfeeding Clinic and Institute recommends fenugreek capsules. Other herbs that are recommended for increasing milk supply is raspberry leaf and alfalfa. However, before using herbal supplements while breastfeeding, be sure to consult with a doctor or your pediatrician.