The impact of diet on breast milk

Requirements for vitamins A, B6 and C, iodine and zinc increase by more than 50% for breastfeeding mothers. However, lactation may protect against iron deficiency in the mother, which is thought to be due to the fact that breastfeeding prolongs the period of amenorrhoea [1].

Our breastfeeding food supplement Post essentials helps to meet your requirements for vitamins A, B6, C, zinc and iodine. It contains 17 vitamins and minerals, to cover the needs of breastfeeding mothers.

Certain compounds remain stable regardless of the mother's dietary intake. This means your body will draw on its reserves to ensure an adequate supply to the infant. 

Proteins

The protein concentration in human milk is not affected by the mother's diet, but increases with the mother's body weight relative to her height, and decreases in mothers producing larger quantities of milk [2]. Studies conducted in Europe and the United States have not reported any relationship between total protein content in breast milk and maternal intake of total protein, animal protein, or plant protein [3].

Carbohydrates

Regarding carbohydrates, no relationship has been found between total carbohydrates in breast milk and the mother's dietary energy intake. Equally, no significant relationship has been found between lactose in breast milk and a high-protein diet, nor with a maternal diet high in fat and low in carbohydrates compared with a low-fat, high-carbohydrate diet [4].

Cholesterol

Cholesterol levels in milk remain constant even in women with hypercholesterolaemia, and only increase in severe cases of pathological hypercholesterolaemia [5].

Most minerals

Regarding minerals and trace elements, their content is relatively resistant to variation in maternal intake. For example, in a study conducted in North America, no correlation was observed between iron, calcium, magnesium and potassium in breast milk and the mother's corresponding dietary intake [6].

Vitamins E, K and B9

Overall, vitamin levels will vary according to maternal intake, but some will be less affected. Vitamin E status is little affected, and vitamin K status is relatively independent of intake, although vitamin K supplementation can increase its concentration in breast milk [7].

Regarding folates (vitamin B9), the concentration in breast milk is maintained even when the mother is deficient in this vitamin. As a result of this maintained level of folate secretion in milk, women with low intakes will see their own levels decline as lactation progresses [8]. Folates and vitamin B12 present in human milk are bound to whey proteins; consequently, the maternal factors regulating protein secretion are more likely to affect the levels of these vitamins in milk in the short term than fluctuations in maternal vitamin intake [9].

The quantity of long-chain polyunsaturated fatty acids

The amount of fat consumed by the mother will be reflected in milk lipid levels, particularly for long-chain polyunsaturated fatty acids [10]. Women with low fat reserves will have lower lipid levels in their milk. A study conducted in the United States found a higher proportion of total fat in breast milk with a maternal diet characterised by low carbohydrate and high fat content, compared with a diet high in carbohydrates and low in fat [11]. 

Fat quality, with DHA

A Danish study reported a higher proportion of DHA in breast milk among mothers who consumed fish compared to those who did not, and among women who consumed oily fish compared to mothers who did not [12]. Similarly, maternal supplementation with 1 g of DHA per day significantly increases DHA levels in milk, which consequently improves the dietary DHA intake of breastfed infants [13]. Maternal DHA levels decline during breastfeeding, reflecting the transfer into milk of a fatty acid that is important for the child's development [14]. Likewise, the concentration of arachidonic acid in breast milk is dose-dependently associated with the consumption of foods rich in this fatty acid among breastfeeding mothers [15].

Vitamins A, D, C and the B vitamins

Milk levels of vitamins depend largely on the mother's dietary intake. This is the case for vitamin A, vitamin D, vitamin C and the B vitamins. Of the B vitamins, these are the ones that will vary the most according to diet.

A Russian study found a positive correlation between vitamin C in breast milk and maternal dietary intake of vitamin C.

It also reported significant correlations between thiamine (vitamin B1) and riboflavin (vitamin B2) in breast milk and maternal diet [16]. Similarly, for vitamin B6, a study concluded that concentrations in breast milk and infant status almost certainly reflect maternal intake and status [17].

Iodine and selenium

As for minerals, they are relatively stable, but a few may be affected. Milk levels of iodine and selenium will vary according to intake [18]. 

Our postnatal vitamins post essentials will help you meet your needs for these essential nutrients. With 17 vitamins and minerals, it will support you throughout your breastfeeding journey.

Among the pollutants, we can mention dioxin, mercury, DDT (insecticides) and PCBs (polychlorinated biphenyls) — chemical substances used in construction, now banned due to their high toxicity, but which persist in the environment because of their very slow natural decomposition. Pollutants are present all around us, in the food we eat as well as in the air and in certain products.
 

Some women will have higher levels of pollutants, particularly first-time mothers, smokers, those who regularly consume alcoholic drinks, those with a higher body mass index (as pollutants are stored in fatty tissue), and older women [19]. 

Some pollutants can find their way into breast milk via adipocytes (fat cells), where they are stored. Fluctuations in body weight can encourage these transfers, as fat is mobilised. The level of these pollutants will decrease throughout the period of lactation.
 

The major factor affecting the level of dioxin contamination in breast milk is diet, which accounts for more than 90% of the dioxins found in the body. They are found in particular in fatty meats, oily fish, and certain dairy products [20].
 

But the benefits of breast milk far outweigh the potential transfer of pollutants. Research in recent years shows that even when slightly contaminated, breast milk remains by far the best choice for babies!! And the best for our already heavily polluted planet. 

To find out more, have a look at our article "Is breast milk polluted?”.   

The concentration of certain nutrients can vary depending on maternal intake, particularly with regard to fats and certain vitamins and minerals; while others will remain stable (proteins, carbohydrates, and most minerals), sometimes at the expense of the mother's bodily reserves, as is the case with folates. 

Your milk will always be adapted for your baby, even if this comes at a cost to you. It is very important to eat well, avoid restrictive diets, and not become fixated on breastfeeding and weight loss. The key is to consume all the essential nutrients for both you and your baby. 

No need to panic about pollutants. They may be found in breast milk, but its benefits always outweigh any potential contamination.