Eating meat causes low testosterone? Study on animal vs milk vs plant protein shows surprising results. Check the best protein source

Protein plays a significant role in the diet of a man, as it helps the body to maintain muscle mass and to carry out a number of essential functions. Common sources include meat, eggs and milk while lentils, beans, nuts and other plant foods provide alternatives. But could the source of protein be tied to men’s testosterone levels too?

A new study from Finland examined the diets and hormone levels of over 2,500 men. They found that men who consumed more animal protein had lower average testosterone levels, and those who consumed more plant protein had higher levels.

The results, published in the International Journal of Food Sciences and Nutrition in September 2026, provide an interesting view of the relationship between protein sources and male hormones.

What did researchers find about animal and plant protein?

The study by the University of Eastern Finland included 2,546 men aged 42 to 60. Researchers examined their dietary habits and compared them with blood measurements of total testosterone and sex hormone-binding globulin (SHBG), a protein that binds sex hormones and transports them through the bloodstream.

The results showed a difference between men with the highest and lowest animal protein consumption. Those in the highest-intake group had average testosterone concentrations 1.2 nanomoles per litre (nmol/L) lower than those who consumed the least.

Plant protein showed the opposite association. Men with the highest plant protein intake had testosterone levels 1.1 nmol/L higher on average than those in the lowest-intake group.

The researchers looked at associations between factors such as age, body mass index, lifestyle, other dietary habits and health.

Dairy protein and meat protein

A closer analysis revealed that different animal protein sources were not associated with testosterone levels in exactly the same way.

Higher dairy protein intake was associated with lower total testosterone as well as lower SHBG concentrations. Meat protein, meanwhile, was associated with lower SHBG levels but showed no clear association with total testosterone.

On the plant side, protein from vegetables and other non-cereal sources was linked to greater total testosterone. These included legumes, nuts, seeds, mushrooms, fruit and vegetables.

It’s an important distinction because the overall relationship between animal protein and lower testosterone doesn’t mean eating meat only has the same relationship.

Should men switch to plant protein for higher testosterone?

The findings do not establish that replacing meat or dairy with plant protein will increase testosterone. The researchers examined existing dietary habits and blood test results rather than asking participants to change their diets and tracking their hormone levels.

The study used four-day food records collected between 1984 and 1989 as part of the University of Eastern Finland's ongoing Kuopio Ischaemic Heart Disease Risk Factor Study.