Effect of Diet on Testosterone in Men’s Health

Testosterone has important roles in men’s health. After the age of 40, there is approximately a 1% decrease in testosterone per year. Men in their 70’s have average testosterone levels 35% lower than younger men.

Many men nowadays are seeking testosterone replacement therapy, as well as alternative strategies to improve testosterone levels. Despite a large amount of research on nutrition in this area, much of the data remains inconclusive, or must be interpreted carefully in the context of appropriate nutrition in supporting overall health. 

This month’s nutrition article explores the known roles of diet and supplements on testosterone levels, with a particular emphasis on men’s health. 

What is testosterone, and why is it important in men’s health?

Testosterone is a hormone produced primarily in the testes. It is involved in regulation of sexual health, lean muscle mass, metabolism, cognition, mental health, bone density, and cardiovascular function.  As noted above, testosterone decreases with age. Also, one can have a condition known as hypogonadism, where your sex glands produce very little testosterone. 

Medications, diet, sleep, and other lifestyle factors can all influence testosterone levels.

Calories matter, but in context

Macronutrients are the calorie containing nutrients, and include protein, carbohydrates, and fat. Research indicates that low energy availability in the body (i.e., excessive caloric restriction or over-exercise without adequate nutrition) can have a negative impact on your endocrine system, including testosterone levels.

For example, one study on healthy adults indicated a 40% reduction in total caloric intake was associated with a significant decrease in testosterone, despite a high percentage of the caloric intake coming from protein. Similar results were found in two other studies examining negative daily calorie balance as a result of exercise in elite body builders and distance runners.

But in some cases, caloric restriction could be warranted for overall health, including that of your endocrine system and testosterone.

For example, obesity is linked to lower levels of testosterone, hypogonadism, and many chronic diseases. In these individuals, a long term, sustainable weight loss strategy that includes moderate caloric restriction, may benefit both testosterone levels and overall health. Moderate caloric restriction is also increasingly becoming considered to be beneficial to healthy individuals in longevity studies.

This is a prime example of how context matters in research and in practice. Caloric restriction may benefit one person, but not another. One must weigh associated benefits, risks, and the overall goal of a dietary intervention strategy.

Dietary fat and testosterone

Fat is a critical nutrient for hormone production, including testosterone. Some research suggests that higher fat diets may increase testosterone levels. Furthermore, some researchers have suggested a diet higher in dietary cholesterol can have a positive impact on testosterone levels. 

But is a high-fat diet good for overall health? Recommended fat amounts are between 20-35% of total calories. The research studies referenced above used higher percentages of total fat, such as those ones may find in extreme low-carb diet approaches, like keto.

Furthermore, a diet high in saturated fats is generally associated with low grade inflammation and chronic disease such as heart disease, fatty liver, and type 2 diabetes.

The best quality nutrition guidelines to prevent chronic disease recommend to shift fat sources away from saturated fats and towards unsaturated fats, which are hallmarks of the Mediterranean dietary approach. For example, monounsaturated fats are considered heart healthy, and can be found in nuts, seeds, avocados, olive oil. 

Omega-3 fats also have many well researched health benefits, and can be found in fatty fish, some eggs, and plant-based foods such as flaxseed, chia seeds, hemp hearts, spirulina, soybeans, and canola.

Protein supplements and the effect of soy

Researchers have asked if the type of protein you eat impacts testosterone levels, and if protein supplementation provides any benefit. This is largely because lean muscle mass is regulated in part due to circulating testosterone, and some types of protein have been implicated in testosterone levels.

For example, there is evidence indicating whey protein supplementation may be a superior protein source for increasing testosterone in response to training. However, studies also suggest most protein interventions in the context of training have a net positive effect.

Researchers have also investigated the role of soy protein on testosterone levels. There is a persisting hypothesis that soy protein may decrease testosterone. This hypothesis is based on the understanding that soy has significant amounts of compounds called isoflavones, which are also called phytoestrogens. These compounds can in fact have both estrogen agonist and antagonist actions in the body. Hence the controversy. 

But does the hypothesis hold water? A recent review of the scientific literature concluded that soy protein does not have any negative effect on testosterone. In fact, soy protein has proven health benefits including lowering LDL cholesterol, potential decreased risks of developing certain types of cancer, and may also moderately lower blood pressure.

My advice – include soy protein from food sources (Ex. tofu, edamame, soybeans, soy milk, tempeh) for general health without testosterone-related concerns. Consider whey protein supplementation as part of a resistance training routine to potentially optimize testosterone levels.

What about vitamins and minerals? 

Micronutrients include vitamins, minerals, and water. Some micronutrients are involved in regulation of testosterone production.

For example, vitamin D, magnesium, and zinc are all important nutrients with proven roles in maintaining optimal testosterone levels. Several studies have shown that supplementation with these micronutrients may increase testosterone levels. 

But do we need to supplement? Vitamin D we get from the sun and food sources, but food sources are limited and in Canada we do not get enough Vitamin D from the sun year-round due to our latitude. In fact, many Canadians are Vitamin D deficient. 

Discuss your vitamin D needs with your doctor. In general, I recommend taking between 1000-2000 International Units (IU) of Vitamin D3 per day through supplementation, particular in winter.

Dietary intervention to meet magnesium and zinc needs through food sources is a potentially safer strategy than supplementation, and likely will involve foods with additional nutrition.

Excellent food sources of zinc include meat, shellfish, legumes, seeds, nuts, dairy, eggs, whole grains, potatoes, and dark chocolate.

Excellent food sources of magnesium include dark leafy greens, bananas, fatty fish, whole grains, seeds, tofu, legumes, nuts, avocados, and again, dark chocolate!

While supplementation for some may be warranted, most vitamins and minerals can be obtained as part of a healthy, balanced diet.

Natural health products

Many natural products are thought to increase testosterone by inhibiting a testosterone-converting enzyme called aromatase. Many are also so-called ‘adaptogens’ with a variety of biological functions. Prominent examples that have been researched for potential improvement of testosterone levels include ginseng, ashwagandha, and saw palmetto. 

While some research is promising, most research remains largely inconclusive due to research study limitations. For example, small sample size, animal studies, poor controls, or research subjects with health conditions not common to the general population.

Testosterone “boosting” supplements

As discussed above, many natural products with potential to improve testosterone are lacking in high quality evidence. 

For example, one recent research study investigated supplements claiming to boost testosterone. They found that only 25% of these had data to support the claim, and 10% actually contained ingredients that may have a negative effect on testosterone levels. Many of the supplements had doses of vitamins and minerals well above the dietary upper limits, creating potential toxicity concerns.

Furthermore, and as per legislation from the US food and drug administration, “Unlike drugs, supplements are not intended to treat, diagnose, prevent, or cure diseases”. Despite this legislation, there continues to be an abundance of supplements and herbal remedies that make claims that imply such effects, including those promoting benefits towards testosterone-related medical conditions. Buyer beware!

Also, worth considering – supplements are a growing multibillion dollar enterprise. Regulation frequently comes under question, as there simply is not enough public health officials to monitor such a vast market. A natural product number (NPN) is the best current safety control on supplements and natural health products, yet studies continue to identify product concerns within the industry, even those with an NPN number.

Before considering supplementation, please seek guidance from your family physician. Your doctor can help you understand the benefits and risks of incorporating new supplements, including potential safety concerns or medication interactions.

Bringing it all together

Testosterone-related dietary information on the web is abundant with misinformation, and a high prevalence of poorly researched supplements. Even for myself, as a registered dietitian and former researcher, this topic has been particularly interesting yet challenging to navigate into tangible recommendations that support both overall health and improve testosterone levels in males. It is clear that larger, well-designed research studies are needed.

That said, research has given us interesting insights into how diet can manipulate testosterone levels. We know that specific micronutrients (Ex. zinc, magnesium, and Vitamin D) play large roles in production and regulation of circulating testosterone levels.

Caloric restriction may negatively impact testosterone levels in otherwise healthy individuals, but may positively impact testosterone levels in obese individuals if in the context of a sustainable weight loss strategy. 

Dietary manipulation of macronutrients such as total fat, and to a lesser extent protein (in combination with training) can impact testosterone production. However, some of the studies impose conditions that may not be applicable to the general public, or may come at a cost to a balanced nutrition strategy for overall health.

Research on dietary supplements, including traditional roots and herbs may potentially increase testosterone levels. However, many of the studies are too small or lacking in quality to make definitive conclusions. There are also several risks associated with purchasing supplements claiming to boost testosterone.

Finally, there is evidence that diets high in ultra-processed foods and foods of low nutrient density (i.e. foods with very little vitamin and/or mineral content on a per calorie basis), may reduce testosterone levels. 

So basically, eat a healthy, balanced, and varied diet of whole foods. A Mediterranean dietary pattern is a good foundation for optimizing the nutrients known to be involved in supporting optimal testosterone function. 

While a healthy diet and a healthy body weight can help optimize testosterone levels, so can other lifestyle factors such as sleep, stress reduction, and physical activity. Please book an appointment or contact me here if you have questions regarding nutrition and supplements in testosterone.

Dan Neuman
Registered Dietitian MSc