What foods cause high SHBG?

According to consensus research, vegetarian and vegan men have consistently higher SHBG levels than meat-eaters, suggesting dietary factors play a significant role. But what foods cause high SHBG specifically? Certain dietary patterns and individual foods are known to affect this important protein, which regulates the availability of sex hormones in the body.

Quick Summary

Certain dietary patterns and food types, including high-fiber and low-fat diets, phytoestrogen-rich foods like soy, and excessive alcohol consumption, can lead to elevated levels of sex hormone-binding globulin (SHBG).

Key Points

• High-Fiber Diets: Vegetarian and vegan diets, typically rich in fiber, are associated with consistently higher SHBG levels in studies.

• Low-Protein and Low-Fat Intake: Diets low in protein and fat, or those involving extreme caloric restriction, can lead to increased SHBG production.

• Soy and Flaxseed: These foods contain phytoestrogens and lignans, respectively, which can influence SHBG production, though research on soy's effect is mixed.

• Excessive Alcohol: Heavy and chronic alcohol consumption is a known contributor to significantly elevated SHBG levels.

• Caffeine and Specific Nuts: Coffee and certain nuts like walnuts and almonds have also been linked to increased SHBG in some research.

• Balance is Key: Increasing protein intake and moderating fiber can help lower SHBG, highlighting the importance of balanced macronutrient consumption.

Understanding Sex Hormone-Binding Globulin (SHBG)

Sex hormone-binding globulin (SHBG) is a protein produced by the liver that binds to sex hormones, primarily testosterone and estrogen, and transports them in the blood. The amount of these hormones that are 'bound' by SHBG is not available for the body's tissues to use, while the 'free' or unbound hormones are readily available. Therefore, having high SHBG levels means that more sex hormones are bound, resulting in lower levels of free, biologically active hormones. A number of dietary factors can influence the liver's production of this protein, impacting overall hormonal balance.

Dietary Patterns Linked to Increased SHBG

Several broad dietary approaches have been associated with higher SHBG levels, though the effects can sometimes be contradictory and depend on individual physiology.

Vegetarian and Vegan Diets

Research has consistently shown that men on vegetarian and vegan diets have higher SHBG levels compared to those who eat meat. This is thought to be a result of a combination of factors typical in these diets:

• Higher Fiber Intake: As seen in numerous studies, higher fiber intake is correlated with increased SHBG.
• Lower Protein Intake: Some studies suggest that lower protein intake, often a characteristic of these diets, can lead to elevated SHBG, particularly in men.
• Lower Fat Intake: Similarly, low-fat diets have been linked to an increase in SHBG levels.

Low-Protein and Low-Fat Diets

Diets characterized by low protein and low-fat content are frequently cited as contributing to higher SHBG. This may be particularly relevant in cases of malnutrition or disorders like anorexia nervosa, where extreme caloric restriction and low protein intake lead to significantly elevated SHBG levels. A high-protein diet, conversely, has been shown to potentially lower SHBG.

Specific Foods and Compounds That May Cause High SHBG

Beyond general dietary patterns, certain foods and compounds have been shown to influence SHBG production more directly.

Phytoestrogen-Rich Foods, like Soy and Flaxseed

• Soy Products: Soy contains phytoestrogens, plant-derived compounds that can mimic estrogen in the body. The effect of soy on SHBG is not entirely clear, with some studies showing an increase, others no effect, and some even showing a decrease depending on the form and quantity consumed. However, the estrogen-like effects are often cited as a possible reason for increased SHBG levels observed in some individuals.
• Flaxseed: Flaxseed is a notable source of lignans, which are a type of phytoestrogen. Studies have shown that lignans can increase the synthesis of SHBG, and flaxseed supplementation has been linked to decreased testosterone levels in women with PCOS, suggesting an increase in SHBG is at play.

Excessive Alcohol Consumption

While moderate alcohol intake may not have a significant impact or could even lower SHBG, excessive and chronic alcohol consumption is strongly associated with a marked, several-fold increase in SHBG levels, particularly in men. This effect is pronounced even in the absence of severe liver damage and is a potential marker for heavy drinking.

Caffeinated Beverages

Studies on caffeine have shown a positive correlation between caffeine consumption and plasma SHBG levels. Research suggests that caffeine may increase SHBG indirectly by influencing other processes in the body, such as increasing adiponectin production in adipose tissue, which subsequently increases hepatic SHBG production.

Specific Nuts

Some nuts, such as walnuts and almonds, are rich in specific types of fatty acids that have been linked to increased SHBG production. A 2011 study on women with PCOS found that consuming walnuts increased SHBG by 12.5% and almonds by 16%, possibly due to their high content of polyunsaturated and monounsaturated fatty acids, respectively.

Low-Carbohydrate Diets (can also cause high SHBG)

While some diets suggest reducing carbohydrates to lower SHBG, extreme caloric restriction or very low-carbohydrate diets can actually lead to an increase in SHBG, especially when coupled with low fat intake. This highlights the complex interplay between different macronutrients and their effects on hormonal regulation. A diet balanced in protein, fat, and carbohydrates is generally recommended for maintaining hormonal health.

Influences on SHBG Levels: A Comparison

Factor	Effect on SHBG	Explanation
High Fiber Diet	Increase	Increases liver production and may be linked to lower circulating estrogens and androgens.
Low Protein Diet	Increase	Less protein intake is associated with higher SHBG concentration.
Excessive Alcohol	Significant Increase	High consumption impairs liver function and massively raises SHBG.
Underweight/Anorexia	Increase	Extreme low caloric intake and malnutrition leads to elevated SHBG.
Soy/Flaxseed	Potential Increase	Phytoestrogens and lignans can influence estrogen and SHBG levels, though results are mixed.
High Protein Diet	Decrease	Higher protein intake is associated with lower SHBG levels.
Refined Carbs/Sugar	Decrease	Spikes insulin, which inhibits SHBG synthesis.
Resistance Training	Variable	Can increase SHBG with intense training, but effects vary.

What to Eat for Optimal SHBG Balance

For those aiming to influence their SHBG levels, a balanced and moderate approach is often best. Rather than focusing solely on foods that increase or decrease SHBG, prioritizing overall health is key.

Increase Protein Intake

Incorporating sufficient protein from sources like lean meats, fish, eggs, and legumes can help regulate SHBG levels. A higher protein diet has been shown to be associated with lower SHBG levels.

Moderate Fiber and Phytoestrogens

If you have high SHBG, you may consider moderating your intake of very high-fiber foods and potent phytoestrogen sources like flaxseed. A balanced intake of vegetables, whole grains, and fruits is still crucial for health, but extremes may need to be addressed.

Increase Healthy Fats

While low-fat diets can increase SHBG, incorporating healthy fats from sources like olive oil and avocado can support hormonal health. A Mediterranean diet, which includes healthy fats, has been associated with beneficial hormonal changes.

Conclusion: Seeking Balance for Hormonal Health

Understanding what foods cause high SHBG involves recognizing how dietary patterns, macronutrient ratios, and specific food compounds impact this liver-produced protein. Diets high in fiber, low in protein and fat, and vegetarian or vegan diets are all consistently linked to higher SHBG levels. Additionally, heavy alcohol consumption and certain phytoestrogen-rich foods like flaxseed can also play a role. Conversely, increasing protein and moderating excessive fiber can help lower SHBG levels. For personalized advice, it is always recommended to consult with a healthcare provider or a registered dietitian. Monitoring dietary intake and making gradual, sustainable changes is the most effective strategy for managing SHBG and achieving overall hormonal balance.

For more detailed research, refer to studies like the one on dietary components and SHBG levels in men.

Frequently Asked Questions

Does a high-fiber diet definitely cause high SHBG?

Studies have shown a positive correlation between higher fiber intake and increased SHBG levels, especially in men. However, the effect can be influenced by other factors in the diet and differs between individuals.

Can eating soy products raise my SHBG levels?

Soy contains phytoestrogens which can potentially increase SHBG, but research is inconsistent, with some studies finding an increase and others no significant change. The effect can depend on the amount and type of soy product consumed.

Is excessive alcohol consumption a major factor for high SHBG?

Yes, chronic and excessive alcohol consumption is a significant cause of elevated SHBG, even in individuals without marked liver damage.

What kind of diet should I follow if I have high SHBG?

A diet that emphasizes higher protein intake and a balanced mix of healthy fats, while managing excessive intake of fiber and refined carbohydrates, can be beneficial. Consulting a doctor is recommended for a personalized plan.

Do vegetarian and vegan diets always lead to high SHBG?

Numerous studies show that vegetarians and vegans tend to have higher SHBG levels than meat-eaters, possibly due to higher fiber and lower protein/fat intake. However, the effect can be influenced by other factors like body weight and individual metabolism.

Can low-fat diets increase SHBG?

Yes, some research indicates that diets low in fat can lead to an increase in SHBG levels. This is often contrasted with higher-fat diets which have been shown to lower SHBG.

Are there any foods that help lower SHBG?

Foods high in protein, such as lean meats, fish, and eggs, and healthy fats like those found in olive oil may help lower SHBG. Reducing refined carbohydrates and sugar intake can also contribute to lower SHBG by improving insulin sensitivity.