Milk is a nutrient-packed fluid that supplies protein, healthy fats and key vitamins to support health and culinary uses.
Often identified as a dairy beverage or lacteal secretion, it blends texture and taste to enrich diets worldwide.
What Is Milk?
Milk refers to the lacteal secretion produced by female mammals to nourish their offspring.
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Definition of Milk
Milk is the white fluid secreted by mammary glands. It serves as the principal source of sustenance for newborn mammals, delivering natural hydration and vital nourishment. In human diets, it provides a familiar dairy beverage prized for its creamy profile and mild sweetness.
Common Types of Milk
Several varieties exist, each with its own taste and nutrient spread.
- Cow’s milk: Around 3.5 % fat, widely available in pasteurised or UHT forms.
- Goat’s milk: Tangy flavour, often easier to digest for some people.
- Sheep’s milk: High in protein and rich fats, ideal for cheese and yoghurt.
- Buffalo milk: Denser texture and higher fat content, common in South Asian cuisine.
- Camel milk: Lower lactose levels, consumed in arid regions for its electrolyte balance.
What Nutrients Does Milk Provide?
Milk comprises a balance of macro and micro nutrients. For a detailed breakdown, see our guide on dairy nutrient composition.
Macronutrients in Milk
- Protein (≈ 3.4 g per 100 ml): Casein and whey proteins that support tissue repair.
- Fat (≈ 3.6 g per 100 ml): Mix of saturated and unsaturated fatty acids for energy.
- Carbohydrate (≈ 4.8 g per 100 ml): Primarily lactose, which fuels blood sugar and brain function.
Micronutrients in Milk
Milk delivers around 120 mg of calcium per 100 ml, plus phosphorus and magnesium for skeletal strength. It also features vitamins D (for calcium absorption), B12 (for nerve health) and A (for vision and immunity).
How Milk Is Processed?
Commercial milk often undergoes treatments to ensure safety and improve shelf life.
Pasteurisation and Safety
Most milk is heated to at least 72 °C for 15 seconds (known as high-temperature short-time pasteurisation) to remove harmful pathogens. This step helps to extend shelf life while retaining taste and nutrients.
Homogenisation and UHT
Homogenisation breaks fat globules into smaller particles, preventing cream separation and giving a smooth consistency. Ultra-High-Temperature (UHT) treatment heats milk above 135 °C for a few seconds, creating long-life milk that can remain unopened for months.
What Are the Benefits of Milk?
Regular intake of milk can support bone health, muscle development and hydration. For advice on calcium requirements, see our calcium intake guide.
Supports Bone Health
Calcium and phosphorus in milk combine to form strong bone matrix. Vitamin D in fortified varieties further aids mineral absorption, which may help to reduce the risk of osteoporosis in later life.
Promotes Muscle Growth and Hydration
The protein and branched-chain amino acids in milk assist in muscle repair after exercise. With natural electrolytes such as potassium, milk can also help to restore fluid balance and lessen post-workout soreness.
How to Choose and Store Milk Safely?
Proper selection and storage will keep milk fresh and preserve its flavour.
Selecting Quality Milk
Examine the use-by date and inspect the carton or bottle for any damage. Opt for organic or grass-fed labels if you prefer milk from pasture-raised animals.
Proper Storage Tips
Store milk at or below 4 °C in the main compartment of the fridge rather than the door. Seal tightly after each use to prevent odour absorption and maintain consistent chill.
What Alternatives Exist to Dairy Milk?
Those seeking lactose-free or plant-derived options have a range of substitutes to choose from.
Plant-Based Milk Alternatives
- Almond milk: Nut-derived, low in calories and naturally lactose-free.
- Soy milk: High in plant protein and rich in B vitamins.
- Oat milk: Provides dietary fibre and a creamy mouthfeel.
- Rice milk: Mild taste, often fortified with vitamins and minerals.
For more on vegan choices, see our article on plant-based milk alternatives.
Other Dairy Options
- Lactose-free milk: Treated with lactase enzyme to break down sugar.
- A2 milk: Contains A2 beta-casein protein, which some find gentler on digestion.
- Fermented drinks: Kefir and buttermilk offer probiotics for gut health.
Frequently Asked Questions
Here are some questions and answers:
What is lactose?
Lactose is the natural sugar in milk. People lacking the enzyme lactase may experience discomfort after drinking regular milk.
Can vegans drink plant-based milks?
Yes. Almond, soy, oat and other plant-derived milks are entirely free of animal products and suit a vegan lifestyle.
How long does opened milk last?
Once opened, fresh milk should be consumed within 5–7 days if kept refrigerated at or below 4 °C.
Is milk suitable for adults?
Milk can form part of a balanced diet for adults, supplying high-quality protein and calcium for bone maintenance.
Is raw milk safe to consume?
Raw milk has not been heat-treated and carries greater risk of bacterial contamination. It is regulated differently across UK regions.