is milk healthy? insights from ayurveda and modern science

Table of contents

• What is a healthy diet?
  1. Ayurvedic framework
  2. WHO framework
• What are the concerns around milk and human health?
• Ayurveda on milk
  1. Properties of milk
  2. Benefits of milk
  3. When is milk contraindicated?
• Science on milk
  • Summary of clinical trials
  • Impact on blood pressure
  • Cardiovascular disease risk
  • Impact on LDL-cholesterol 
  • A1 β-Casein, A2 β-Casein 
• Milk processing considerations
  • Raw, pasteurized, or homogenized?
  • A1 or A2 milk?

 

To answer a question on whether something is healthy or not, we need to first have a framework that defines what is healthy. I will use two frameworks: Ayurveda and the dietary guidelines set by the World Health Organization (WHO). 
The Ayurvedic Framework
​Ayurveda recommends the following foods to be appropriate for regular consumption as part of a healthy diet. These can broadly be categorized into those supporting body structure (muscle, bones, cells), and those promoting healthy digestion. Note that there are other foods that are important for health, but the ones below are deemed essential for everyone, regardless of their Prakrti, or constitution. 

1. Whole grains: rice, wheat, and barley are references in the Brihat Trayi: growth material - provides nourishment, increases strength
2. Lean meats (ex. goat, chicken, does not include sea food): growth material - builds muscle
3. Lentils (green gram): growth material - increases strength, provides nourishment
4. Milk (Cow's milk): growth material - increases immunity and strength, rejuvenates, nourishes all the body tissues
5. Ghee (from cow fat): enhances digestive fire and immunity
6. Water: digestive - warm/hot water promotes digestion and facilitates proper elimination of waste
7. Honey: improves appetite and digestion, protects the heart, prevents clogging of body channels
8. Rock salt: stimulates digestion (read this for a detailed review on salt)
9. Indian gooseberry (alma): promotes digestion and proper removal of waste

 

The WHO framework
Healthy Diet Recommendations:

• Consume at least 400 g (five portions) of fruit and vegetables daily, excluding starchy roots.
• Include legumes (e.g., lentils and beans), nuts, and whole grains (e.g., unprocessed maize, millet, oats, wheat, and brown rice) in the diet.

Limit free Sugars Intake:

• Limit free sugars to less than 10% of total energy intake, with an ideal target of less than 5% for added health benefits. Free sugars include those added to foods or drinks by manufacturers, cooks, or consumers, as well as sugars naturally present in honey, syrups, fruit juices, and fruit juice concentrates.

Fat Consumption Guidelines:

• Restrict total energy intake from fats to less than 30%.
• Prefer unsaturated fats, found in fish, avocado, nuts, and oils like sunflower, soybean, canola, and olive.
• Reduce saturated fats to less than 10% of total energy intake.
• Minimize trans-fats, with a suggested intake of less than 1% of total energy intake.

Salt Intake:

• Limit daily salt intake to less than 5 g (about one teaspoon), ensuring it is iodized.

The primary distinction between Ayurvedic and WHO frameworks is that Ayurveda considers the properties of food as a whole, while the WHO breaks down food into sugars, fats, salt, protein, etc. Modern guidelines often quantify food in terms of energy (calories) and recommend limits on sugars and fats. ​

 

What are the concerns around milk and human health?

1. Link to cardiovascular diseases (CVD): Over 70% of the fat in whole milk is saturated fat. Saturated fats have come under scrutiny due to their purported links to cardiovascular diseases (CVD). The narrative traces back to the 1950s with the emergence of the diet-heart hypothesis, championed by Ancel Keys. 
2. Adverse Reactions to Milk and Chronic Diseases:

• Cow’s Milk Protein Allergy: Primarily affecting infants and children, eliciting immunological responses, with symptoms ranging from skin issues to respiratory and gastrointestinal discomfort.
• Lactose Intolerance: Widespread, affecting 70% globally, resulting from reduced lactase enzyme activity, leading to gastrointestinal discomfort.​

These concerns highlight potential issues associated with milk consumption. Understanding these aspects is crucial for making informed decisions about including milk in one's diet.

 

​Ayurveda on milk
Ayurveda originated thousands of years ago in an era when cows were raised naturally, consumed grass, and were milked during natural pregnancies without artificial insemination or hormone use.
Milk Processing in Ayurveda:​ 

• The exact process of milk treatment is unclear. This article suggests boiling milk with the addition of 25% water for increased digestibility, though the source is unspecified. In general, Ayurveda does not recommend consuming anything raw. Therefore, it seems logical that raw milk was at least warmed before consumption to improve digestibility. 
• Milk must not be heated repeatedly. 
• Before refrigeration, ghee served as a means to preserve milk's nutrients for extended periods. 

Ayurvedic properties of milk 

• Heavy (hard to digest)
• Sweet in taste
• Cooling

Benefits of milk according to Ayurveda

• Nourishing
• Improves strength and immunity
• Beneficial for the brain (improves memory and intellect)
• Effective for constipation

Who benefits most from consuming milk

• Individuals with Vata and Pitta predominant Prakrti
• Those with Vata or Pitta disorders like constipation, acidity, weakness, or faintness
• Especially beneficial for Vata Prakrti individuals, particularly if their diet lacks meat

Who should use caution in consuming milk

• People who are not used to drinking milk
• People who suffer from Kapha disorders such as obesity, diabetes, arteriosclerosis, and insulin resistance

Milk as Medicine:
Milk is typically tempered with spices suitable for one's constitution or disorder.

• Vata Prakrti benefits from milk warmed with cardamom and cinnamon.
• Pitta Prakrti benefits from warm milk sweetened with rock sugar (mishri).
• Kapha Prakrti and related disorders benefit from skim milk warmed with turmeric, black pepper, and dry ginger.
• Milk must never be consumed with foods that are salty and sour. Milkshakes with sour fruit, breakfast that includes milk and fruit, or fruit juice, and milk drinks with powders containing salt or preservatives like citric acid are unhealthy and can impair digestion. 

Understanding the Ayurvedic perspectives helps tailor milk consumption to individual constitutions and health conditions, maximizing its benefits while considering potential drawbacks.

 

Science on milk
Multiple reviews have examined clinical trial data concerning the impact of milk on cardiovascular health, with a focus on saturated fats and their relation to cholesterol levels, particularly LDL-cholesterol. A summary of three papers (reference 1, reference 2, and reference 3) is presented below. 
Diet-Heart Hypothesis Revisited: 

• ​The diet-heart hypothesis centered on the impact of saturated fats on cholesterol levels, especially LDL-cholesterol, as a precursor to cardiovascular disease (CVD).

Clinical Trial Data (1960s-1970s): 

• Rigorous, large-scale clinical trials involving about 67,000 participants challenged the hypothesis. Trials, lasting 1-7 years, did not conclusively support the idea that reducing saturated fat intake reduces CVD risk.

Cochrane Review 2020: 

• Recent Cochrane reviews question the efficacy of reducing saturated fats in improving cardiovascular outcomes.
• Emphasizes the limitations of focusing solely on LDL-cholesterol and the oversight of critical clinical trial data.

On the other hand, several benefits of cow's milk were reported from the clinical trials. 
Benefits of cow milk
Milk and Blood Pressure: 

• Clinical trials indicate that milk fat consumption is not associated with increased blood pressure, and some studies even show a reduction.

Cardiovascular Disease (CVD) Risk:

• Large, randomized, controlled trials from the 1960s and 1970s did not conclusively support the diet-heart hypothesis.
• Dairy product intake in adults was associated with improved body composition, weight loss, and reduced risks of type 2 diabetes and cardiovascular disease, particularly stroke.
• Reductions in saturated fat intake, even with consistent reductions in total cholesterol, did not reliably reduce long-term clinical cardiovascular outcomes, such as heart attacks and deaths.

Impact on LDL-Cholesterol:

• Saturated fats, including those found in milk, do raise LDL-cholesterol concentration.
• However, reducing saturated fat intake and lowering LDL-cholesterol did not consistently lead to reduced cardiovascular risk in the long term.
• The decrease in LDL-cholesterol primarily reflected reduced levels of large LDL particles, which have a weaker association with heart disease risk.

Milk and Neurological Diseases:

• Milk consumption inversely associated with the risk of cognitive disorders, including Alzheimer’s disease.
• Increased risk of Parkinson’s disease with dairy product intake; the mechanism is unclear.

A1 β-Casein, A2 β-Casein, and Chronic Diseases:

• Caseins constitute a significant portion of milk proteins, with A1 and A2 β-casein variants. The A1 variant has been associated with gastrointestinal symptoms akin to lactose intolerance.
• The role of milk and dairy in chronic diseases is complex. While some studies suggest a protective role against obesity and Type 2 Diabetes (T2D), associations with cardiovascular diseases, cancer, and neurological diseases exhibit variability.

​Role of Diet Matrix:

• Saturated fats, when part of the food matrix in products like cheese and yogurt, are associated with essential nutrients like calcium, vitamins A, D, and B12, and proteins.
• The overall dietary pattern, particularly carbohydrate intake, plays a crucial role in the metabolism of saturated fat.​

 

Milk processing considerations
Raw, pasteurized, or homogenized?
A significant difference between ancient times and the modern era is the evolution of the dairy industry. Raising a cow or two at home has morphed into massive cattle farms to provide billions of people enough milk. This impacts the food that cows eat - natural grass, legumes, alfalfa, and hay to processed food made from corn and soy that are grown at mass agricultural scale using pesticides, and genetic modification. Most cows are also treated with hormones to increase milk production that causes great suffering and pain to these animals.

• Raw milk is the least processed and thus considered most beneficial according to Ayurveda. Local, organic dairy farms, where cows graze on natural grass, offer an option for obtaining raw milk with better nutritional content.
• What about pasteurization? Pasteurization is the process of heating milk to a slightly elevated temperature for a certain period of time. There are two methods - one involves heating the milk to 72 degreesC (for reference, water boils at 100C) for 15 seconds, immediately followed by chilling the milk. A second approach is to heat the milk to 63C for 30 minutes, followed by natural cooling. Industrial pasteurization uses the former method as it is much faster. The benefits of pasteurization is to increase the shelf life of milk and prevent disease by bacterial elimination. Some studies show that the heating process reduces vitamins B2 and C, and other vitamins that are not present in significant quantities. 
• Should you boil raw milk? The answer should be NO from a standpoint of preserving its heat sensitive nutrients.  My preference is to pasteurize it using the second method above; gently heat and hold and cool naturally. The most fail safe way to do this is to use a double walled milk boiler such as this one. Boiling milk to 100C will deplete it of nutrients more severely than pasteurization. 
  • After pasteurization and cooling of milk, the thick layer of cream can be skimmed off, leaving behind milk with much lower fat for consumption. 
  • This cream can be cultured to make ghee. 
• Homogenization is the process of breaking down milk fat into very small lipid molecules by subjecting milk to high pressures. The purpose of homogenization is to further extend the shelf life as well as improve the texture and taste of milk by preventing the separation of cream from milk. Homogenization also allows large scale dairies to mix milk from different breeds of cows.
  • Homogenized milk can be purchased as whole milk (which must contain 3.25% fat), reduced fat (2%), low fat (1%), and no fat or skim milk (0-0.5% fat).
  • The health impact of homogenization has been shrouded in controversy. The main nutritional impact of homogenization is a drastic reduction of milk fat globule membrane (MFGM) and an increase in adsorption of casein proteins in the body, compared to untreated milk. The impact of this profoundly altered composition on human health, such as cardiovascular disease, immunity etc., is controversial.  
• A1 or A2 milk? ​A1 and A2 are variants of one of the proteins found in milk, called beta casein. Unlike pasteurization or homogenization, A1 and A2 beta casein are genetic variants of the beta casein protein, as opposed to an alteration of milk via processing. "A1" milk has both A1 and A2 beta casein proteins in a variable proportion depending on the breed of the cow, where as A2 milk must be so labeled only if it is completely devoid of A1 beta casein. This paper presents a good overview on the comparison between A1 and A2 milk based on animal and human clinical studies and the key conclusion is that A2 milk produces less digestive discomfort that A1 milk. 

I hope this article serves as a valuable guide to help you navigate the complexities of milk consumption by offering insights from both traditional wisdom and modern scientific understanding. Practical insights into pasteurization, homogenization, and the A1 vs. A2 debate should empower you to make choices aligned with your nutritional goals and health preferences. ​