This is a fictional, illustrative case created for education. It is not medical advice, diagnosis, or treatment, and does not describe a real person.

The supplement stack that made everything worse

Sarah, 41: six months of doing everything right — methylfolate, B12, NAC, glutathione — and feeling progressively worse. The clue was not in her homocysteine. It was in what her CBS gene was doing with her supplements.

Persona

Sarah, 41, Female, South Asian, Healthcare administrator.

Six months on a methylation supplement stack — methylfolate, B12, NAC, glutathione — and I feel worse than when I started. More fatigue, new anxiety, jaw and shoulder tension I can't explain.

Family history: Mum has IBS and sulphite sensitivity — reacts to wine and dried fruit. Dad takes metformin for type 2 diabetes.

Clinical picture

Symptoms

Labs

Medications

Supplements

Lifestyle

Genetics

Doing everything right, feeling worse

Sarah is 41 and works in healthcare administration. She is not someone who ignores her health. After reading about methylation, she built a supplement stack that looked exactly right on paper: methylfolate, methylcobalamin, NAC, liposomal glutathione, magnesium. She gave it six months. By month three, she was more fatigued than when she started. By month five, a new anxiety had appeared — low-level, persistent, unexplained. Her jaw and shoulders held a tension she could not release. Her practitioner told her to give it more time.

The clue her homocysteine hid

Her homocysteine came back at 6.2 µmol/L — well inside the reference range, technically ideal. So nothing pointed to a methylation problem. But homocysteine being low does not mean the pathway is running well. It can also mean homocysteine is draining out the other end — being consumed faster than it is produced. When the sulfur pathway is overactive, homocysteine is pulled down so efficiently that the number looks fine even as the downstream byproducts accumulate.

The sulfur trail

Two details her standard workup missed. Her urinary sulfite was elevated — a sign that sulfite is being produced faster than her body can clear it. And she had already noticed, without connecting it to her supplements, that wine and dried fruit made her feel unwell. Sulphite sensitivity is not a random intolerance. It is a signal that the sulfur pathway is already under strain — and that adding high-dose sulfur-containing supplements to that system creates exactly the environment she had been living in for six months.

The supplements were adding fuel

NAC is a precursor to cysteine, which feeds directly into the sulfur pathway. Glutathione, when broken down in the gut, also releases cysteine. For most people these are helpful. For Sarah — with a CBS variant that already pushes homocysteine through the sulfur route faster, and a BHMT backup route that is less efficient — the extra cysteine load compounded an already overloaded pathway. Sulfite built up. Hydrogen sulfide accumulated. The fatigue, the anxiety, the tension: these are consistent with a nervous system under sulfur stress, not a system that needed more support.

Why her homocysteine looked perfect

The CBS variant creates a picture that looks reassuring on standard labs. Homocysteine is low-normal — the pathway appears to be working. But the methylation cycle upstream was being quietly depleted: less homocysteine available to recycle into methionine and SAMe. SAMe is the methyl donor for mood regulation, stress response, and dozens of other processes. A low-normal homocysteine with the wrong supplements can mean the system is draining, not thriving.

What Sarah brings to her clinician

Sarah's check-in: 14 days of tracking

Daily fatigue & anxiety check-in. Sarah logged fatigue and anxiety every morning. The first week looked the same as the previous six months. After pausing NAC and glutathione on day 8 and adding molybdenum, the pattern shifted.

Eight weeks of data — before and after

Each square is one day. Darker red means worse. Green means a better day. Gray means not logged. Week 5 is when Sarah paused NAC and glutathione.