Understanding the Science: Does Yogurt Raise IGF-1?

October 3, 2025 •

3 min read

While some studies have linked dairy consumption to increased levels of insulin-like growth factor-1 (IGF-1), research specifically examining yogurt presents a more complex picture. This article dives into the scientific debate to determine whether yogurt truly raises IGF-1 and what factors might influence its effect on your body's growth pathways.

Quick Summary

Studies on yogurt's effect on IGF-1 show contradictory results, potentially due to the fermentation process which can degrade some of the raw milk components. Key factors influencing IGF-1 levels include the type of protein (casein), live probiotics, and overall dietary context, rather than just the presence of fermented dairy.

Key Points

Fermentation Reduces IGF-1: The process used to make yogurt significantly decreases the concentration of IGF-1 present in raw milk, distinguishing its effects from unfermented dairy.
Inconsistent Human Studies: Research on yogurt's impact on circulating IGF-1 is mixed, with some studies finding no association while others suggest a link to yogurt protein.
Probiotics Can Modulate IGF-1: The live cultures in yogurt may influence IGF-1 levels indirectly through gut-hormone interactions and the production of short-chain fatty acids.
Protein Source is a Factor: The type of protein, particularly the casein in milk, is a key driver of IGF-1 stimulation, but the fermentation process can alter protein structure.
Lifestyle Influences are Strong: Overall IGF-1 levels are more broadly affected by factors like exercise, sleep, age, and total diet, which should be considered alongside individual food choices.
Yogurt Retains Health Benefits: Despite the complex IGF-1 picture, yogurt remains a nutrient-dense food that provides calcium, protein, and probiotics, which benefit overall health.

What is IGF-1 and Why Does It Matter?

Insulin-like growth factor-1 (IGF-1) is a hormone crucial for regulating cell growth, proliferation, and differentiation, primarily produced in the liver in response to growth hormone (GH). While essential for development, particularly in childhood, excessive levels have been linked to health risks in adults, while low levels can negatively impact muscle and bone health. Maintaining balanced levels is important. Overall dairy consumption, particularly milk, is known to increase serum IGF-1 levels, leading to questions about the impact of fermented dairy like yogurt.

The Mixed Scientific Findings: Does Yogurt Raise IGF-1?

Research on yogurt's specific effect on IGF-1 levels is inconsistent. A 2020 study found no association between yogurt intake and IGF-1 levels, unlike milk which showed a significant link. However, a 2024 analysis suggested yogurt proteins were positively associated with increased IGF-1. This conflicting evidence highlights the complexity and potential variations based on the type of fermented product and individual factors.

The Impact of Fermentation

The fermentation process used to make yogurt appears to play a significant role. Studies indicate that IGF-1 concentrations in yogurt decrease substantially during fermentation, with lactic acid bacteria potentially using IGF-1 as a nitrogen source. This reduction in native IGF-1 may explain why yogurt's impact differs from unfermented milk.

Protein Type and Probiotic Activity

Milk contains both whey and casein proteins, with casein potentially having a stronger IGF-1 stimulating effect. While yogurt contains both, fermentation alters their structure. Furthermore, the probiotics in yogurt can influence IGF-1 levels through the gut microbiome, with some strains potentially increasing IGF-1. This suggests a complex interaction involving the fermented product, gut bacteria, and metabolic byproducts.

Yogurts vs. Other Dairy: A Comparison

The following table compares the potential effects of different dairy products on IGF-1 levels based on available research:


Dairy Product	Key Characteristics	Effect on IGF-1 (Based on Research)
Milk (Cow's)	Unfermented, contains both casein and whey protein.	Strongly associated with increased circulating IGF-1 levels.
Yogurt (Fermented)	Contains probiotics, casein, and whey. Fermentation reduces native IGF-1.	Mixed results, but generally considered to have a more moderate or complex effect than milk. Some studies show no association, while others suggest a positive link with yogurt protein.
Cheese (Fermented)	Concentrated protein, fermented.	One study found no association between cheese intake and IGF-1 levels.
Kefir (Fermented)	Contains a wider variety of probiotics and yeast than yogurt.	Some studies suggest kefir consumption might lower IGF-1 compared to other dairy products, but research is limited.
Soy Yogurt (Plant-based)	Plant-based protein, fermented with bacterial cultures.	Different protein composition; generally considered to have less impact on IGF-1 than animal dairy.

Conclusion

The evidence regarding whether yogurt raises IGF-1 is complex. While unfermented milk is consistently linked to higher IGF-1, yogurt's effect is less clear. The fermentation process in yogurt significantly reduces native IGF-1, though its protein content and probiotics can still influence the GH-IGF-1 axis. Yogurt's impact is likely more moderate than milk's and depends on factors like probiotic strains and individual health. Given its nutritional value and probiotic benefits, unsweetened yogurt remains a healthy dietary choice. Managing IGF-1 is best achieved through a balanced diet, regular exercise, and healthy lifestyle habits.

Final Takeaways on Yogurt and IGF-1

Yogurt's effect is less pronounced than milk's: Unlike unfermented milk, yogurt does not show a consistent, strong link to elevated IGF-1 levels across all studies.
Fermentation reduces native IGF-1: The process of fermentation significantly degrades the IGF-1 found in raw milk, mitigating its potential impact.
Protein and probiotics play a role: The casein protein in dairy can influence IGF-1, while the probiotics in yogurt can also modulate the gut-hormone axis, creating a complex interaction.
Overall diet is key: Your IGF-1 levels are impacted by a wide range of factors, including total protein intake, sleep, and exercise, not just a single food.
Choose wisely: Opting for unsweetened yogurt with live and active cultures ensures you get the benefits of probiotics without the downsides of added sugar, which can negatively impact metabolic health.

Related Resource

For more in-depth information on IGF-1's broader role in health and disease, consider reviewing some of the research available on the National Institutes of Health website. For example, a 2014 study discusses the association between low protein intake, IGF-1, and mortality risk, offering valuable context on how diet influences this hormone.

Disclaimer: This article is for informational purposes only and is not medical advice. Consult with a healthcare professional before making dietary changes.

Frequently Asked Questions

No, evidence suggests that the fermentation process used to make yogurt and other fermented dairy products actually reduces the native IGF-1 levels found in raw milk. Studies have found that while milk is linked to higher IGF-1, yogurt is often not, or has a more moderate effect.

The primary difference between Greek and regular yogurt is that Greek yogurt is strained to remove whey, resulting in a higher protein concentration. While higher protein intake is generally associated with higher IGF-1, the fermentation of both types means the effect on circulating IGF-1 is likely more moderate than milk, but could still be influenced by the total protein load.

Probiotics, the beneficial bacteria found in yogurt, can influence IGF-1 via the gut-liver axis. They produce short-chain fatty acids that modulate metabolic pathways. Some animal studies have shown that certain probiotic strains can increase IGF-1, indicating a complex interaction.

Yes, many dietary factors influence IGF-1. High intake of animal protein, especially from sources other than yogurt or cheese, can be associated with higher levels. Conversely, calorie restriction and some plant-based diets can lead to lower IGF-1. A balanced diet and healthy weight management are key.

Yes, choosing yogurt with live and active cultures is beneficial for your gut health and may offer protective effects. Since these cultures are responsible for the fermentation that reduces native IGF-1, they are not a primary concern for raising IGF-1 levels, unlike unfermented milk.

IGF-1 levels naturally peak during puberty and decline with age. Regular exercise, particularly resistance training, is known to stimulate GH release and can help maintain healthy IGF-1 levels as you age. Sleep and overall nutritional status are also major factors.

The key is the fermentation. While both milk and yogurt contain protein (including casein), the lactic acid bacteria in yogurt fermentation consume and alter some of the components, including IGF-1, which results in a different, more moderate effect on circulating levels.