So, what causes irregular periods? It is common for teenage girls to experience some irregularity in their menstrual cycle when their period first starts. After menarche, it may take a few months for the menstrual cycle to regulate, and this is perfectly normal. Following these first few months, a teenage girl’s period should start to follow a cycle of approximately 28 days with menstrual bleeding lasting 4-7 days.

I encourage my teenage clients to track their period with an app on their phone or keep a diary. This helps identify any problems. Tracking the period along with any menstrual symptoms such as ovulation pain, appetite changes, sleep disturbance, mood, irritability, and any pain or discomfort helps assess menstrual cycle irregularities.

Nutrition and Diet:

My focus is finding the underlying cause of my clients’ menstrual cycle irregularities, starting with diet and addressing any nutritional deficiencies.

An adequate intake of macronutrients—carbohydrates, proteins, and fats—is essential for hormone production and maintaining a healthy menstrual cycle.

Complex carbohydrates found in whole grains, legumes, fruit, and vegetables are important for energy production and to stabilize blood sugar levels. Stable blood sugar levels support a healthy endocrine system, which regulates hormone production.

Many teenage girls aren’t eating enough protein. Protein deficiency disrupts hormonal feedback systems, leading to decreased production of hormones like progesterone and estrogen. Protein also provides the building blocks for all hormones.

Ensure you have protein with every meal from sources like lean meat, fish, eggs, legumes, tofu, nuts, seeds, and quinoa.

Healthy fats found in olive oil, nuts, seeds, fish, and avocado are vital for hormone production. These healthy fats also aid the absorption of fat-soluble vitamins A, D, E, K, which are important for a healthy endocrine system. Insufficient healthy fat intake is a common cause of menstrual cycle irregularities in teenagers.


Micronutrients, including vitamins, minerals, and phytochemicals found in wholefoods, are co-factors in hormone production and vital for maintaining a healthy menstrual cycle.

Iron: When iron levels are low, less oxygen reaches the tissues and organs. This can disrupt the normal functioning of the ovaries and uterus, potentially contributing to irregular or heavy menstrual bleeding.

Vitamin D is crucial for calcium absorption and bone health but is also important for hormone production. Low levels of vitamin D may be a contributing factor in menstrual cycle irregularities.

Omega-3 fatty acids found in fish, nuts, and seeds are vital for progesterone production. Their anti-inflammatory properties help reduce PMS symptoms.

Zinc levels directly impact hormone production and menstrual health. It is common for teenagers to be low in zinc due to an increased demand to support growth and development. Zinc is found in seafood, pumpkin, nuts, and seeds—not foods most teens eat in abundance.

B vitamins, such as B6, B9, and B12, are essential for energy metabolism and the production of neurotransmitters and hormones. A deficiency in these vitamins can contribute to stress, anxiety, and hormonal disruptions.

Selenium is crucial for hormone health as it supports the synthesis and activation of thyroid hormones. Adequate selenium levels contribute to a well-functioning thyroid, impacting metabolism and overall endocrine balance.

Gut Health:

Our gut microbiome directly influences our hormones. An imbalance in healthy gut bacteria can lead to increased beta-glucuronidase activity, a key enzyme linked to estrogen metabolism and liver function.

Also, the gut microbiome contributes to the production of short-chain fatty acids (SCFAs), which have been shown to influence hormone regulation. SCFAs play a role in supporting a healthy endocrine system and a healthy menstrual cycle.

Stress and Anxiety:

When our body experiences stress, it produces stress hormones, cortisol and adrenaline, to promote alertness. In the short term, this has no impact on other body systems, but chronic stress can disrupt the feedback systems that regulate other hormones, leading to imbalances in hormones such as insulin, melatonin, thyroid hormones, and reproductive hormones estrogen and testosterone.

The intricate interplay between stress and hormonal balance highlights the importance of stress management strategies for maintaining overall health and well-being. Stress is also linked to nutrient deficiencies and gut health. Stress management techniques like Buteyko breathing exercises, herbal medicine, and probiotics can be invaluable in helping with anxiety and chronic stress.

Thyroid Health:

The thyroid gland plays a crucial role in regulating all hormones. While it produces thyroid hormones, these then influence metabolism and energy production and interact with other hormones such as estrogen and progesterone.

Investigating thyroid function may be recommended if addressing diet does not resolve your menstrual cycle irregularities.


Many teenage girls with irregular periods are advised to take the oral contraceptive pill or other synthetic hormonal treatments such as Annovera or NuvaRing. If stress and anxiety are factors, they may be advised to take an antidepressant such as an SSRI. This approach can be helpful for some teenagers, but others find the side effects outweigh the benefits. The downside of this approach is that it does not resolve the underlying cause.

Fad diets and restrictive eating can be a problem for many teenagers, often fuelled by tik tok trends and peer pressure. Empowering teens with an understanding of nutrition is often the first step in helping them understand what foods to choose for their health and well-being.

To address the underlying cause of menstrual cycle irregularities, I recommend first looking at diet, gut health, stress management, and addressing any nutritional deficiencies. If this still does not resolve the irregularities, further investigations into thyroid function, anxiety, and using evidence based herbal medicine to regulate the menstrual cycle can address the underlying cause.

Remember, every child is unique, so finding the right solutions may require some investigation. If you need support managing your menstrual cycle book an appointment and we can investigate and address the root cause.