Preventing Early Puberty: Understanding Dietary and Environmental Influences

To educate children and parents on preventing early puberty, it’s crucial to address the increasing rates and their underlying causes. In Australia, the average age for girls to experience their first menstruation is around 13 years old, but about 12% experience it earlier, between the ages of eight and 11. Alarming trends show that early and very early menarche, particularly before the age of 11, are on the rise. This increases the risk of several adverse health outcomes, including cardiovascular diseases, cancers, spontaneous abortion, and premature death.

Picture from https://www.sciencedirect.com/science/article/pii/S0753332222012963

The rise in early puberty stems from multiple factors, one of the most significant being childhood obesity. Obesity, which is often linked to poor dietary choices and sedentary lifestyles, has been closely associated with early puberty. Children today spend more time on digital devices and less time engaging in physical activity, leading to increased body mass index (BMI). This rise in BMI accelerates pubertal development by disrupting the hypothalamic-pituitary-gonadal axis, causing early hormonal changes.

Picture from: https://www.osmosis.org/learn/Precocious_puberty

In addition to obesity, environmental factors like exposure to endocrine-disrupting chemicals (EDCs) also play a role in early puberty (Table 1). These chemicals, found in everyday products such as plastics (e.g., bisphenol A or BPA), pesticides, and flame retardants, can mimic or block natural hormones, disrupting the normal progression of puberty. EDCs disturb hormonal balance by affecting hormone synthesis and metabolism, leading to early sexual maturation, especially in girls.

Table 1: Common examples of Endocrine-disrupting chemicals (EDCs)

EDCs in daily life	Examples
Plastics and food packaging	Many plastic products, especially those labeled with recycling codes 3, 6, or 7, contain chemicals like Bisphenol A (BPA) and phthalates. These chemicals can leach into food or beverages, particularly when plastic containers are heated or scratched. Items like plastic food containers, water bottles, and the lining of canned foods are common sources.
Personal care products	EDCs are commonly found in personal care items like shampoos, lotions, deodorants, and cosmetics. Ingredients such as parabens and phthalates, which are used as preservatives and to retain fragrances, can interfere with hormonal activity.
Household cleaning products	Many household cleaners, detergents, and air fresheners contain chemicals like alkylphenols and phthalates, which can act as endocrine disruptors. These chemicals help to enhance cleaning power or stabilize fragrances.
Non-stick cookware	Non-stick coatings on cookware, such as Teflon, contain perfluorinated chemicals (PFCs), which are suspected to be EDCs. These chemicals can be released when the cookware is scratched or overheated.
Pesticides and herbicides	Agricultural chemicals such as atrazine, DDT, and glyphosate are known to disrupt endocrine function. These chemicals can remain on conventionally grown produce, so it's essential to wash fruits and vegetables thoroughly or consider buying organic alternatives to minimize exposure.
Furniture and carpets	Flame retardants like polybrominated diphenyl ethers (PBDEs) are added to furniture, carpets, and electronics to reduce fire risks. However, these chemicals can be released into the air and settle in dust, posing a risk when inhaled or ingested over time.
Thermal receipt paper	BPA is often used in the coating of thermal receipt paper. When people handle receipts, especially after washing hands, this chemical can be absorbed through the skin.
Children’s toys	Certain plastics used in children’s toys and teething products can contain phthalates, which can pose a risk if children frequently put these items in their mouths.
Textiles and clothing	Fabrics that have been treated for stain or water resistance may contain per- and polyfluoroalkyl substances (PFAS). These chemicals are used in raincoats, outdoor gear, and stain-resistant carpets.
Canned foods	The lining of most cans used for canned food products contains BPA, which can leach into the food, especially if the food is acidic (such as tomatoes or soups).
Paint and building materials	Volatile organic compounds (VOCs), formaldehyde, and phthalates are often found in paints, vinyl flooring, and other building materials, contributing to indoor air pollution and potential endocrine disruption.
Pharmaceuticals	Some over-the-counter and prescription medications, such as certain types of hormone-based therapies (e.g., oral contraceptives or hormone replacement therapies), can also act as endocrine disruptors when not properly managed or disposed of.

Diet also plays a key role in early menarche. Studies have shown that higher intakes of energy, animal protein, iron, and polyunsaturated fatty acids (PUFAs) are associated with an increased risk of early puberty (Table 2). For example, each additional gram of animal protein consumed daily can cause menarche to begin approximately two months earlier. On the other hand, girls who consume diets rich in fibre and monounsaturated fats tend to experience later menarche. Additionally, diets high in fat and with a high glycemic index can lead to low-grade inflammation in the hypothalamus, which accelerates hormonal changes, further contributing to early puberty.

Table 2. Specific foods under each dietary factor that have been linked to the timing of puberty

Specific foods	Details	Examples
High-energy foods	Sugary snacks and desserts	Cakes, cookies, candies, and pastries contain high amounts of added sugars and fats, which are calorie-dense.
	Fast food	Burgers, fries, pizzas, and fried chicken from fast food outlets are loaded with calories due to their high fat and carbohydrate content.
	Sodas and sugary drinks	These beverages are high in added sugars and provide empty calories without essential nutrients.
	Processed snacks	Chips, crackers, and packaged snack foods are often high in calories, fats, and carbohydrates.
Animal Protein-Rich Foods	Red meat	Beef, pork, and lamb are rich sources of animal protein.
	Poultry	Chicken, turkey, and duck are other significant sources of animal protein.
	Dairy products	Milk, cheese, and yogurt are rich in animal protein, as well as calcium and other vitamins.
	Eggs	Eggs are a versatile source of animal protein and provide essential amino acids.
High Glycemic Index Foods	White bread and pastries	Made from refined flours, these have a high GI.
	Sugary breakfast cereals	Many processed cereals are high in sugar and have a high GI.
	Potatoes, rice	Especially when fried or processed (like in French fries), potatoes have a high glycemic index. White rice, particularly when processed, has a higher GI compared to whole grains like brown rice.
	Sweets and candy	Foods made primarily of sugar, such as candies, chocolates, and sugary desserts, can cause rapid increases in blood glucose levels.
Polyunsaturated Fatty Acids (PUFAs)	Vegetable oils	Oils like corn oil, sunflower oil, and canola oil are rich in omega-6 fatty acids.
	Processed foods	Many processed and packaged foods contain oils high in omega-6 PUFAs.
	Nuts and seeds	Walnuts, brazil nuts, pine nuts, flaxseeds, and chia seeds.
	Oily fish and seafood	Salmon, tuna, sardines, and mussels are excellent sources of omega-3 PUFAs.
Iron-Rich Foods	Red meat	Beef, lamb, and pork are rich sources of heme iron.
	Organ meats	Liver and kidney contain large amounts of iron.
	Fortified cereals	Many breakfast cereals are fortified with iron.
	Legumes	Lentils, chickpeas, and beans are good plant-based sources of non-heme iron.
	Spinach and leafy greens	While lower in bioavailability compared to meat, leafy greens like spinach provide non-heme iron.
High-Fibre Foods	Whole grains	Oats, brown rice, quinoa, and whole wheat are rich in fibre.
	Vegetables	Broccoli, carrots, Brussels sprouts, and leafy greens are fibre-dense.
	Fruits	Apples, pears, berries, and oranges contain high amounts of dietary fibre.
	Legumes	Lentils, black beans, and chickpeas are excellent sources of fibre.
	Nuts and seeds	Chia seeds, flaxseeds, almonds, and pistachios are fibre-rich.
Monounsaturated Fats (MUFA)	Extra virgin Olive oil, peanut oil	A primary source of MUFA, widely used in Mediterranean diets.
	Avocados	High in healthy fats, particularly monounsaturated fats.
	Nuts	Almonds, cashews, and macadamia nuts are rich in MUFAs.
	Seeds	Pumpkin seeds and sesame seeds are good sources of MUFAs.
	Olives	Both green and black olives are rich in monounsaturated fats.

Preventing early puberty requires a focus on both dietary and environmental interventions. Encouraging a balanced diet that limits processed and high-fat foods while increasing the intake of fiber and healthy fats is essential. Additionally, parents should promote physical activity to help children maintain a healthy weight. In cases where girls show signs of early puberty before the age of eight, such as progressive breast development, accelerated growth, or vaginal bleeding, it is important to seek medical advice. Early referral to a specialist and clinical tests, such as bone age assessments and hormone level testing (LH, FSH), can help manage the condition and prevent complications.

Another factor under debate is the relationship between soy-based foods and early puberty, particularly in Western countries. Some studies suggest that higher consumption of soy-based foods may be linked to earlier puberty onset in girls, while others find no conclusive evidence. One explanation for the potential link is the presence of phytoestrogens in soy, specifically isoflavones, which can mimic estrogen and influence hormone levels, potentially triggering earlier puberty. The timing and amount of soy consumed during childhood may also play a role in its impact.

Differences in soy consumption between East and West may also explain why soy appears to contribute to early puberty in Western countries. In East Asia, soy is typically consumed in fermented forms, such as miso, tofu, natto and tempeh, which have lower levels of isoflavones and might reduce estrogen-like effects. In contrast, in Western countries, soy is often consumed in processed forms, such as soy milk and soy protein isolates found in energy bars and meat substitutes, which contain higher concentrations of isoflavones and could contribute to early puberty.

This issue is further complicated by the highly processed nature of many soy-based foods in Western diets. Products like soy milk, soy protein isolates, and soy-based infant formulas expose children to higher levels of phytoestrogens during critical developmental periods. Furthermore, soy consumption in the West is often part of a broader diet high in calories and processed foods, which can lead to obesity, another factor associated with early puberty. The combination of high energy intake and the estrogen-like effects of soy may accelerate pubertal development.

Despite these concerns, research findings on soy and early puberty are inconsistent. Some studies show a link between soy consumption and early puberty, while others find no significant association. Research in East Asian populations, where soy is a common dietary staple, has not consistently shown early puberty, suggesting that the form, amount, and context of soy consumption are key factors in its impact.

To prevent early puberty, it is vital to monitor children’s diet and lifestyle. A balanced diet that limits processed and high-fat foods, while promoting fiber-rich and healthy fats, can help maintain hormonal balance. Additionally, parents should ensure that their children stay active to reduce the risk of early pubertal development. For girls under eight showing signs of precocious puberty, such as progressive breast development, headaches, or vaginal bleeding, an urgent referral to a specialist is necessary to rule out serious conditions like McCune-Albright Syndrome. Girls aged two to six with breast tissue development should undergo bone age assessments and hormone tests (TSH, free T4, LH, FSH, and estradiol) to determine the cause. For girls aged six to eight, a similar evaluation may be sufficient if no alarming symptoms are present.

In conclusion, addressing the dietary, environmental, and lifestyle factors contributing to early puberty is essential for improving long-term health outcomes in children. By promoting healthy eating, physical activity, and reducing exposure to harmful chemicals, parents and healthcare providers can help mitigate the risks associated with early pubertal development. Further research is needed to fully understand the role of soy and other dietary factors in early puberty, especially in Western contexts.

References:

• Canelón, S. P., & Boland, M. R. (2020). The Potential for Climate Change to Impact Women’s Health. International Journal of Environmental Research and Public Health, 17(5), 1703. https://doi.org/10.3390/ijerph17051703

• Diaz-Thomas, A. M., et al. (2023). Endocrine Health and Disparities in Pediatric Populations. The Journal of Clinical Endocrinology and Metabolism, 108(7), 1533–1584. https://doi.org/10.1210/clinem/dgad124

• Papadimitriou, A., & Papadimitriou, D. (2021). Endocrine-Disrupting Chemicals and Early Puberty. Children, 8(6), 492. https://doi.org/10.3390/children8060492

• Nguyen, N. T. K., et al. (2020). Nutrient Intake and Early Menarche Onset in Girls. Nutrients, 12(9), 2544. https://doi.org/10.3390/nu12092544

• Valsamakis, G., et al. (2021). Diet-Induced Hypothalamic Inflammation and Precocious Puberty. Nutrients, 13(10), 3460. https://doi.org/10.3390/nu13103460