Inositol

Inositol is a sugar alcohol that your body makes itself, mostly from glucose. You also get it from food: citrus fruit, beans, nuts and wholegrains. Labels sometimes call it vitamin B8, but it is not a vitamin, because your body does not depend on food for it. Inside cells it works as a messenger, passing on signals from hormones such as insulin. About 95% of the free inositol in the body is the myo form, which is why most supplements start there.

Inositol itself has no authorised health claim in the UK or the EU. EFSA assessed inositol and cognitive function and judged the evidence insufficient. Formulas therefore borrow their wording from added nutrients. Vitamin B6 contributes to the regulation of hormonal activity, and chromium contributes to the maintenance of normal blood glucose levels. Those claims belong to those nutrients, not to inositol. If a pack promises more, read the ingredient panel instead of the front label, or compare products with vitamin B6 on their own.

The forms that genuinely differ

• Myo-inositol: the most studied form and the base of nearly every serious formula.
• D-chiro-inositol: used in small amounts. In blood, myo and D-chiro sit at roughly 40 to 1, which is where 40:1 blends come from. More D-chiro is not better.
• Myo with B6, folate or chromium: for people who want the approved claims of those nutrients alongside.
• Powder or capsules: servings of 2,000 to 4,000 mg mean four to eight capsules of 500 mg. Powder dissolves in water and tastes faintly sweet, which is simpler at that level.

How we choose the inositol we stock

We look at three things: the form, the amount per serving and the combinations that make sense. Myo-inositol is the base we expect to see, with D-chiro-inositol only in small proportions. We prefer servings you can realistically reach, so a scoop of powder or capsules of 500 mg or more, rather than 250 mg capsules that need eight a day. Where vitamin B6 is added, we check it stays within sensible limits. We buy directly from the brands, our compliance team checks every label before it goes live, and we test batches ourselves alongside independent labs. See how we select brands and products.

Who it suits and what to expect

Most inositol formulas are built around cycle and metabolic support, which is why they sit close to our chromium options and to B-vitamin blends. Plain myo-inositol powder is also chosen by people who simply want one ingredient, no additives and full control over the amount.

Be realistic about timing. Most studies ran for twelve to twenty-four weeks before measuring anything, so give it at least two to three months of daily use before you judge it. Because inositol draws water into the gut, a high starting amount can cause mild bloating or loose stools. Starting lower, splitting the serving and taking it with a meal usually settles that within a week. If you are pregnant, breastfeeding or taking prescribed medication, check with your GP first. Products aimed at cycle support sit in our range chosen for women.