Why can’t you drink a gallon of milk? (3+ reasons)

In this article, we will answer the question “Why can’t you drink a gallon of milk?” and discuss the risks of drinking a gallon of milk and what is the daily recommended intake of milk.

Why can’t you drink a gallon of milk?

You can’t drink a gallon of milk because the excessive intake of milk can lead to negative effects on health. Calcium, milk fat and lactose are some compounds of concern when ingested in exceeding doses (1,2,3,4,5). 

Although milk contains important nutrients, including high quality amino acids with improved functionalities, it should be consumed in a limited quantity, according to age and other individualities (2,4).

What are the risks of drinking a gallon of milk?

The risks of drinking a gallon of milk are related to the excessive ingestion of calcium, milk fat, vitamin D and lactose, which can lead to adverse health effects. The following risks are associated to the ingestion of a too high amount of milk or dairy:

Iron deficiency 

According to studies, the excessive intake of calcium can lead to iron deficiency, as calcium can reduce the capacity of the body to absorb iron from the nutrition. 

Especially for children, the consumption of cow milk in a higher amount than the recommended daily intake of 800 mg/d for children, can lead to iron deficiency and anemia (3).

Increased risk of breast cancer 

Higher risks of developing breast cancer is related to the excessive intake of milk and dairy. One factor that can lead to breast cancer is the ingestion of milk fats, especially saturated fats, which induce the higher estrogen concentrations in the body and consequently higher risks of developing breast cancer (1,5).

Other compounds present in milk, such as organochlorines and s IGF-I, a growth factor, are also related to higher risks of breast cancer in the population (5). 

Increased risk of ovarian cancer

The consumption of milk in excess can increase the risks of developing ovarian cancer, according to studies. This is due to the galactose, which is the sugar resulting from the digestion of lactose. Galactose may cause a toxic effect on the ovaries, increasing the risks of cancer (1,5).

In this way, even low fat lactose free milk could bring a health risk, when consumed in excess.

Overload of vitamin D

Milk, when consumed in excess, can also lead to excessive amounts of vitamin D in the diet, especially when fortified milk is consumed, which is the most common milk found in the market. Overload of vitamin D results in higher absorption of calcium.

Higher absorption of calcium, in turn, can lead to hypercalcemia, with negative consequences to the body tissues and heart and hypercalciuria, with negative effect on the kidney, with the formation of renal stones (2).

An overdose of vitamin D is toxic, leading to constipation, diarrhea, fatigue, headache, nausea, and vomiting.

What is the daily recommended amount of milk?

The recommended daily amount of milk is 2 to 3 servings of a cup of 250 mL milk every day for North Americans. However, this recommendation is only if you do not ingest other dairy products. 

If you include yogurt or cheese in the daily diet, you should reduce the ingestion of milk to fit the 2 to 3 daily servings of milk per day.

The recommended daily amount of milk can vary, depending on the Country. For example, in Europe the recommended daily ingestion of milk is 2 to 4 servings of 250 to 500 mL (6).

What is in a gallon of milk?

A gallon of milk there are the following nutrients, as shown in the table below (1):

NutrientIn 100 mL of whole milkIn one gallon of whole milk
Energy (kcal)622347
Water (g)883331
Protein (g)3114
Fat (g)3.5132
Carbohydrates (g)4.7178
Cholesterol (mg)13492
Vitamin A (mg)592233
Vitamin D (mg)0.052
Vitamin B1 (mg)0.042
Vitamin B2 (mg)0.1415
Na (mg)431628
Ca (mg)1094126
Mg (mg)9341

Other FAQs about Milk which you may be interested in.

How long is formula good for in the fridge?

Benefits of drinking milk before bed

Benefits of lactose-free milk


In this article, we answered the question “Why can’t you drink a gallon of milk?” and discussed the risks of drinking a gallon of milk and what is the daily recommended intake of milk.


  1. Pereira, Paula C. Milk nutritional composition and its role in human health. Nutrition, 2014, 30, 619-627.
  2. Scanlon, Kelley S., et al. Subclinical health effects in a population exposed to excess vitamin D in milk. Am j public health, 1995, 85, 1418-1422. 
  3. Bondi, Steven A., and Kenneth Lieuw. Excessive cow’s milk consumption and iron deficiency in toddlers: two unusual presentations and review. ICAN, 2009,1, 133-139.
  4. Elwood, Peter C., et al. The consumption of milk and dairy foods and the incidence of vascular disease and diabetes: an overview of the evidence. Lipids, 2010, 45, 925-939.
  5. Davoodi, H., S. Esmaeili, and A. M. Mortazavian. Effects of milk and milk products consumption on cancer: a review. Comprehen Rev Food Sci Food Safe, 2013, 12, 249-264.
  6. Comerford, Kevin B., et al. Global review of dairy recommendations in food-based dietary guidelines. Front nutrition, 2021, 8, 671999.

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