Does Raw Milk Increase IGF-1? What Science Reveals

December 26, 2025 •

3 min read

Milk, including raw milk, contains the hormone IGF-1, linked to growth. However, the key question is how raw milk specifically influences IGF-1 levels and whether there are significant health implications.

Quick Summary

Both raw and pasteurized milk can elevate IGF-1, primarily due to milk proteins. Raw milk contains IGF-1 itself, but the amino acid content stimulates the body to produce more.

Key Points

Milk Protein Boosts IGF-1: All milk, raw and pasteurized, can increase IGF-1 because milk proteins and amino acids prompt the body to produce its own IGF-1.
Pasteurization Doesn't Affect IGF-1 Boost: Heating milk during pasteurization does not significantly affect its ability to raise serum IGF-1 levels, as this effect is driven by protein content, which remains intact.
Limited IGF-1 Absorption: Most IGF-1 from milk is broken down during digestion, and direct absorption of the hormone is minimal.
Raw Milk Carries Bacterial Risk: Raw milk poses a high risk of containing dangerous bacteria, such as E. coli and Salmonella, which can cause serious illnesses.
Weigh Benefits and Risks: While dairy is linked to IGF-1 benefits like muscle growth, the health risks of raw milk must be considered.
Multiple Factors Influence IGF-1: Genetics, diet, and age also affect IGF-1 levels, not just milk intake.

IGF-1's Role in Milk and the Body

Insulin-like Growth Factor 1 (IGF-1) is crucial for cell growth and metabolism. While essential for normal development, high levels in adults have raised health concerns, including links to certain cancers. Milk from all mammals naturally supports growth and contains nutrients and growth factors, such as IGF-1.

When consuming dairy, the casein and whey proteins are rich in amino acids, like leucine, that stimulate the body's IGF-1 production. Research indicates that milk consumption can increase IGF-1 levels, potentially by 20–30%. This increase comes not just from the IGF-1 already in the milk but from the milk's proteins and amino acids that signal the body to increase its own production.

Raw vs. Pasteurized Milk and IGF-1

Proponents of raw milk argue its unpasteurized state preserves beneficial enzymes and nutrients. However, standard pasteurization does not significantly alter IGF-1 levels; this is because IGF-1 is resistant to standard pasteurization. High-temperature treatments can reduce IGF-1, but the typical process doesn't significantly impact IGF-1. From an IGF-1 perspective, the difference between raw and pasteurized milk is minimal. The milk's protein content, not its raw or pasteurized state, is the primary driver of the IGF-1 response.

Comparing Raw and Pasteurized Milk


Feature	Raw Milk	Pasteurized Milk
IGF-1 Content	Contains IGF-1 naturally.	Contains IGF-1; pasteurization does not significantly lower levels.
Effect on Serum IGF-1	Can increase serum IGF-1 through protein stimulation.	Can increase serum IGF-1 through protein stimulation.
Bacterial Risk	High risk of harmful bacteria contamination.	Heated to kill harmful bacteria, eliminating pathogens.
Nutrient Differences	Contains all original enzymes and bacteria, claimed to offer health benefits.	Maintains vitamins and minerals, without significant nutritional value loss.
Health Safety	Higher risk of serious illness, especially for vulnerable people.	Safe and effective method to prevent foodborne illness.

Factors That Influence the IGF-1 Response

Several factors beyond milk's raw or pasteurized state can influence IGF-1 levels:

Protein Quality and Quantity: The amount and type of protein, including whey and casein, and its rich amino acid profile, particularly leucine, are key to IGF-1 increase.
Dietary Habits: Overall diet, including protein and energy intake, can modulate IGF-1 synthesis.
Genetics: Genetic variations can significantly impact response to dairy and baseline IGF-1 levels.
Fat Content: Some studies suggest a positive correlation between milk's fat content and IGF-1 concentration.
Age and Health Status: The effect of milk on IGF-1 varies with age, and there are notable increases in children.

Digestion of Raw Milk

Advocates of raw milk often claim it contains enzymes that aid digestion, but scientific consensus suggests this is a misconception. The human digestive system effectively breaks down milk proteins and IGF-1 from both raw and pasteurized milk. The IGF-1 from milk is largely broken down during digestion, and its absorption into the bloodstream is minimal. The increase in serum IGF-1 is an indirect effect, driven by the amino acids' signaling.

Health Risks of Raw Milk

It's crucial to acknowledge the well-documented public health risks of consuming raw milk. Health organizations, such as the CDC and FDA, warn against its consumption due to high contamination risk.

Common pathogens found in raw milk include:

Salmonella
E. coli
Campylobacter
Listeria

These bacteria can cause serious and potentially fatal illnesses, particularly in children, pregnant women, the elderly, and those with weakened immune systems. Pasteurization is a safe method to prevent milk-borne diseases without compromising its nutritional value.

Conclusion: Raw vs. Pasteurized Milk

Drinking raw milk does increase IGF-1, but not in a way that is fundamentally different from pasteurized milk. The elevation of IGF-1 isn't primarily from the IGF-1 hormone directly absorbed from the milk, but rather the high protein and amino acid content that stimulates the body's own IGF-1 production. Pasteurization does not significantly alter the milk's protein composition or its effect on IGF-1 signaling pathways, so the raw status is not the defining factor. Those choosing raw milk should be fully aware of the higher risk of bacterial infections, a danger effectively eliminated by pasteurization.

Ultimately, milk consumption, whether raw or pasteurized, and its impact on IGF-1 levels, involves considering benefits and risks. For most people, the potential benefits of consuming milk—including the IGF-1-driven muscle growth and recovery—must be weighed against the undisputed and serious health risks associated with drinking raw, unpasteurized milk.

For more information on the dangers of raw milk, you can visit the FDA.

Frequently Asked Questions

Milk increases IGF-1 because its proteins, like whey and casein, provide amino acids like leucine, which signal the body to produce more IGF-1.

No, significant absorption of intact IGF-1 from milk into the bloodstream is unlikely. The hormone is typically degraded during digestion.

No, they don't significantly differ in their effect on IGF-1. Pasteurization doesn't destroy the milk proteins that stimulate the body’s own IGF-1 production. The main difference is the safety risk, not the IGF-1 impact.

Some studies have found an association between high IGF-1 levels and increased cancer risk, like prostate and breast cancer. However, the role of dietary IGF-1 is still researched.

There is no established safe level for IGF-1 in milk, as it's a natural dairy component. The FDA concluded that IGF-1 from milk presents no increased health risk because it is not significantly absorbed.

Raw milk has a substantial risk of contamination with bacteria such as E. coli, Salmonella, and Listeria. These can cause severe foodborne illnesses.

The IGF-1 effect is mainly linked to milk's protein and amino acid content. Reducing overall milk and dairy intake would be a more direct way to influence this dietary impact, rather than choosing between raw or pasteurized versions.

The relationship between milk, IGF-1, and cancer risk is complex and debated. Consulting a healthcare provider or a registered dietitian is recommended for personalized advice on dietary choices and health concerns.