Magnesium aluminium silicate Also known as Fuller’s Earth, a refined and purified cosmetic clay.

Magnesium ascorbyl phosphate A stabilised, synthetically derived version of vitamin C, primarily used as an antioxidant in sunscreen products.

Magnesium chloride A natural salt of Magnesium, which you may find in a shampoo.

Magnesium nitrate Produced by the reaction of Magnesium oxide with Nitric acid. Nitrates are preservatives (Sodium nitrate, for instance, is used in cured meats, and is also known as Saltpetre).

Maltodextrin A sugar obtained from starch, and used as a ‘film-former’, and to condition skin and hair.

Manganese gluconate Manganese is a naturally-occurring mineral; this ingredient (which is synthesised from Gluconic acid) is said to hydrate and rejuvenate skin.

Manganese violet A mined mineral, which is also listed as CI 77742. Used in colour cosmetics.

Menthone glycerin acetal Flavouring ingredient derived from the mint herb.

Methylchloroisothiazolinone This was introduced into cosmetic formulations to replace Formaldehyde; it’s used as a preservative in a broad range of products (from shampoo to aftershave); can cause allergies and contact dermatitis.

Methyl glucose dioleate An ester of Methyl glucoside and Oleic acid. Methyl glucoside is present in all parts of the rose (flower, leaves, stems etc.), but can also be synthesised from a reaction between methanol and glucose.

Methyl glucose sesquistearate A semi-synthetic ingredient created from Methyl glucoside and Stearic acid; according to at least one source, it may cause dermatitis in some individuals.

Methylheptly isostearate An ester of Caprylic alcohol and Isostearic acid.

Methylisothiazolinone A preservative. Not one of our all-time favourite ingredients, because it is a known sensitiser which can cause allergic reactions. Because of that, its use in many countries is restricted to very tiny concentrations in a finished product.

Methyl 2-octynoate A synthetic fragrance ingredient which must be listed as a separate fragrance component on labels because it is known to cause perfume allergies in some people.

Methylparaben One of the ‘contentious’ paraben family of preservatives, widely used for its anti-fungal action. Few ingredients trigger such violent debate as parabens. We have always taken a precautionary approach, although it appears that several of the studies that link parabens with breast cancer, for instance, were flawed (or at least flimsy). The bottom line is that we would welcome much more research into this thorny subject. Some parabens can be irritating to skin. There are many alternatives to parabens appearing in formulations as manufacturers find creative ways to avoid using them – a response to the fact that so many brands prefer to be able to say their products are ‘paraben-free’.

Mica A shimmering mined mineral pigment.

Micrococcus lysate An extract of powerful enzymes, which is said to help skin recover from UV-activated skin damage. It may also help assist the natural tanning process.

Microcrystalline wax Petroleum-derived wax, widely used in nail polishes and ‘cake’ cosmetics (pressed powders, eyeshadows, etc.)

Myristyl alcohol A white crystalline ingredient derived from fatty acids, and used to create a velvety feel in hand creams, cleansers, body lotions etc.

Myristyl myristate A thickening agent and emollient in very wide use, of synthetic or semi-synthetic origin, sometimes from coconut.

Oleyl alcohol A commonly-used cosmetic ingredient derived from fish oils.

PPG-2 Myristyl ether propionate A synthetic ingredient derived from Myristyl alcohol and Propionic acid; PPG is short for Polypropylene glycol and Polyoxypropylene glycol, which are both synthetic ingredients – see under ‘P‘ – here.