Teenage Girls & Autoimmunity:A mother’s perspective, a clinician’s concern

Teenagers often seem unstoppable. Despite questionable diets, erratic sleep, and sky-high stress, they power through. Or at least — that’s how it looks on the outside.

As a mum of two teenage girls, I’m no stranger to the whirlwind of adolescence. They’re growing fast, juggling school and university, friendships, hormones, and independence. From the outside, they seem to bounce back from anything — and most of the time, they do. But as someone living with multiple sclerosis (MS) and supporting other women with MS, I can’t help but wonder what’s going on beneath the surface for many girls their age.

Adolescence isn’t just a time of growth — it’s a time of profound physiological vulnerability. And increasingly, research suggests it may be a critical window when autoimmune conditions begin to take shape, long before symptoms become obvious.

A Crucial Window for Immune Health

We’re told that teenagers are resilient — and in many ways, they are. But we now understand that adolescence is also a time of heightened immune sensitivity, especially for girls. Hormonal shifts, ultra-processed diets, exposure to hormone-disrupting chemicals, chronic stress, and gut imbalances all affect something called immune tolerance — the immune system’s ability to distinguish friend from foe.

When that system becomes confused, it can start reacting to things it shouldn’t — food proteins, gut bacteria, even the body’s own tissues. This loss of tolerance is at the heart of autoimmune disease.

Hormones & Autoimmunity: The Missing Conversation

Sex hormones — especially oestrogen and progesterone — are powerful regulators of the immune system. Their rise during puberty doesn’t just influence mood and menstruation; it also shapes long-term immune function.

• Oestrogen is broadly immune-stimulating, which can be helpful in the right balance — but both high and low levels may increase the risk of immune overactivation.

• Progesterone, by contrast, helps to calm and regulate the immune system. It supports immune tolerance and reduces inflammation.

• Androgens (like testosterone) tend to have a protective effect, which partly explains why autoimmune diseases are more common in females — even starting in adolescence.

  
  

Scenarios That Can Tip the Balance:

• Anovulatory cycles (common in early puberty and PCOS): Without ovulation, there’s no progesterone production — meaning oestrogen can act unopposed.

• Excess body fat: Fat tissue produces oestrogen and promotes chronic, low-grade inflammation.

• Xenoestrogens: Many personal care products used by teens contain synthetic chemicals that mimic oestrogen, potentially disrupting hormonal and immune signaling.

Diet & Immune Stress: The Hidden Cost of Modern Eating

Adolescent girls often have higher nutrient needs than any other life stage — yet many are running on diets that are nutrient-poor and sugar-rich.

Patterns That Increase Autoimmune Vulnerability:

1. Nutrient Deficiencies

   Deficits in vitamin D, zinc, magnesium, omega-3s, and selenium can impair immune regulation, increase inflammation, and weaken gut health.

2. Gut Disruption from Processed Foods

   Ultra-processed, low-fibre diets reduce microbial diversity and can damage the gut lining — increasing "leaky gut," which allows toxins and bacteria to trigger immune reactions.

3. Excess Sugar

   High sugar intake affects insulin levels, disrupts hormone balance, and inflames the gut — all of which feed into immune dysfunction.

Antibiotics & Gut Health: A Long-Term Consideration

Many teens today have been exposed to repeated rounds of antibiotics — for ear infections, acne, or other childhood illnesses. While these medications are sometimes necessary, they can deplete beneficial gut bacteria and damage gut lining integrity.

This kind of disruption is increasingly being linked to autoimmune conditions as gut health plays a central role in training the immune system to know what’s safe and what’s not.

A Window of Opportunity

Adolescence isn’t just a time of change — it’s a time of opportunity. When we understand how hormonal, nutritional, and environmental factors interact with the immune system, we can take small, proactive steps that may protect long-term health.

That doesn’t mean micromanaging every snack or banning mascara. But it does mean understanding that the environments we create and the habits we support can have a lasting impact on long-term health. Immune balance begins early. And by tuning into that reality, we might just change the health trajectory of the next generation of women.