The studied and the traditional

Black seed oil, Nigella sativa, is the one thing on my shelf with a published human trial behind it in autoimmune thyroid disease: a small eight-week study of forty people in which TSH and thyroid antibodies fell and free T3 rose. Castor oil on the navel has no thyroid trial evidence at all. I use both. Only one has data, and I will not blur that line.

this is the fifth of eight letters about solving my own thyroid. two oils side by side on the same shelf, and two completely different kinds of evidence.

Why these two oils are in the same letter

Because the internet recommends them in the same breath, and that is the problem. Both appear on the same list, in the same confident tone, with the same promise attached. One has a randomised trial. The other has a grandmother. Both can be worth something, but not the same thing.

I promised in the first letter to tell you where the evidence is good and where it is only tradition. This is the letter where that costs me something, because castor oil is the one I love and the one with nothing behind it.

What does the black seed oil research actually show?

One small trial, with results worth attention. Forty people with Hashimoto's thyroiditis, aged 22 to 50, were randomly assigned powdered Nigella sativa or a placebo for eight weeks. In that group TSH came down, anti-TPO antibodies came down, free T3 went up, and body mass index and VEGF, a marker tied to inflammation, both fell.

Now the limits, which matter as much. Forty people is a small group, eight weeks a short window, and medicine is full of promising single studies that did not survive repeating. There is a quieter problem too: a falling antibody number is not the same as a woman feeling better. Antibodies are what the paper could measure. Feeling better is what we came for.

How I take it, and the cautions nobody puts on the label

A teaspoon of the oil in the morning. It is peppery and bitter and tastes like something that means it. The trial used the powdered seed rather than the oil, so I am one step from what was tested, and I would rather say so.

The cautions are real and short. Nigella sativa may lower blood sugar and blood pressure, so if you take medication for either, this is a conversation with your doctor, not a decision made alone in a health food shop. It may affect clotting, so it comes off the list before surgery, and it is not for pregnancy or breastfeeding without medical advice.

One piece of housekeeping took me too long to learn. Levothyroxine is absorbed best on an empty stomach, and many things interfere with it, iron and calcium among the best documented. I keep everything several hours from my morning tablet, and would ask a pharmacist about your list rather than copy mine. The minerals letter covers this from the selenium side.

Castor oil, and why I am calling it tradition

There is no meaningful human trial evidence that castor oil on the skin changes thyroid function. None that I could find, and I looked properly, hoping to. What exists is a very old practice and a great many women, me among them, who find it comforting.

What I do is simple. Warmed castor oil on the navel at night, sometimes a cloth over the lower belly, then fifteen minutes of lying still in the dark. Asked honestly why it helps, I would not tell you the oil reached my thyroid. I would tell you it bought fifteen minutes of warmth and stillness at the end of a day that had none. That is not nothing. It is not the same claim.

Three notes. Topical only, never swallowed, because castor oil taken internally is a stimulant laxative. Patch test if your skin is reactive, and it stains permanently, so use an old cloth.

What I would do if I were starting again

1. Get the bloods first, before any oil or powder. Which tests to ask for is the second letter.
2. Do not change your medication. Not the dose, not the timing, not without your doctor.
3. Change one thing at a time, and give it eight weeks. Start four at once and you will never know which worked.
4. Keep the tradition if it comforts you, and keep calling it tradition. The honesty is what lets you trust the rest of your list.
5. Write down how you feel, not only what the number did.

Frequently asked questions

Does black seed oil help with thyroid problems?

One small published randomised trial suggests it might. Forty people with Hashimoto's thyroiditis, aged 22 to 50, took powdered Nigella sativa or a placebo for eight weeks. In that group, TSH and anti-TPO antibodies fell and free T3 rose. A promising start, not a settled answer.

Can black seed oil replace thyroid medication?

No. Nothing in this letter replaces thyroid hormone replacement, and no supplement has been shown to do that. Keep taking your medication exactly as prescribed and speak to your doctor before adding anything, including black seed oil.

Do castor oil packs work for the thyroid?

There is no meaningful human trial evidence that castor oil applied to the skin changes thyroid function. It is a traditional practice rather than a studied one, and that is how I describe it. The warmth and the stillness may account for most of what women feel.

When should you take supplements if you take levothyroxine?

Levothyroxine is absorbed best on an empty stomach, and many foods and supplements interfere with it, iron and calcium among the best documented. I keep everything several hours from my morning tablet. The spacing differs by supplement, so ask your pharmacist.

Who should not take black seed oil?

Anyone pregnant or breastfeeding, on medication for blood sugar or blood pressure, or approaching surgery should speak to a doctor first, because Nigella sativa may lower blood glucose and blood pressure and may affect clotting. Raise it too if you take any regular medication.

Next letter, red light at night. There are published trials on photobiomodulation and the thyroid, which surprised me, and a wide gap between them and what a device bought online does. The series lives in the first letter, beside exercise, inverted.

With love from Bali,
Myrah