E-numbers / Thickeners & emulsifiers / E470b
also: Magnesium stearate
Magnesium combined with common fatty acids, used as an anti-caking agent and release agent in baked goods, supplements and processed foods.
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Sweeteners (Sorbitol, Aspartame, Sucralose, Acesulfame K), Flavourings, Anti-Caking Agent (Magnesium Salts of Fatty Acids), Colour (Brilliant Blue FCF)
Magnesium salts made by combining magnesium with fatty acids such as stearic acid, palmitic acid and oleic acid.
Magnesium salts made by combining magnesium with fatty acids such as stearic acid, palmitic acid and oleic acid. The fatty acids involved are the same types found naturally in everyday foods including meat, dairy and vegetable oils. The resulting salts are waxy, powder-like solids.
In powdered or granular foods it acts as an anti-caking agent, coating particles so they slide past each other and do not clump. In baking and confectionery it functions as a release agent, preventing dough or candy from sticking to equipment and moulds. It can also act as a mild emulsifier, helping fat and water mix in certain products. When it reaches the digestive tract it dissociates into magnesium ions and fatty acid molecules, both of which the body handles through normal metabolism.
Most commonly found in tablet and capsule food supplements (as a flow agent to help powders run through machinery), powdered drink mixes, dried soups, cocoa powder, chewing gum, confectionery coatings, and some baked goods. Also used in dried egg products and processed cheese powder. On a UK ingredient label it appears as E470b or 'magnesium salts of fatty acids'.
EFSA's 2018 re-evaluation concluded that E470b dissociates in the gastrointestinal tract into magnesium ions and fatty acid carboxylates. Both components follow normal dietary metabolism pathways. The fatty acids released are structurally identical to those already present in everyday food at far higher amounts.
E470b dissociates in the gut to fatty acids and magnesium, both of which are normal dietary constituents metabolised through established pathways. Dietary exposure from authorised uses contributes at most around 5% of total saturated fat intake.
Bacterial mutation tests on closely related compounds including magnesium stearate returned negative results. A carcinogenicity study with sodium oleate (a closely related fatty acid salt) found pancreatic adenomas but EFSA reviewers considered these non-carcinogenic and attributed them to a mechanism not relevant to human dietary exposure at authorised levels.
Bacterial reverse mutation assays on magnesium stearate and related fatty acid salts were negative. EFSA found no concern for mutagenicity for the group.
A carcinogenicity study with sodium oleate showed pancreatic adenomas; EFSA considered these non-carcinogenic findings and did not raise a carcinogenicity concern for the group.
EFSA noted that dedicated subchronic, chronic and reproductive toxicity studies on the salts themselves were absent. The panel addressed this by read-across from extensive existing data on the parent fatty acids (evaluated separately as E570), which are among the most studied dietary components in existence. No follow-up concern was raised.
No dedicated subchronic, chronic or reproductive/developmental toxicity studies existed for the fatty acid salts. EFSA used read-across from fatty acid (E570) data and concluded no numerical ADI was needed.
People with known hypersensitivity to specific fatty acids (for example stearic acid or palmitic acid) should check the label, as the fatty acid composition of E470b can vary by manufacturer. This is uncommon. Anyone monitoring magnesium intake for medical reasons should note it contributes a small additional source. Look for 'E470b' or 'magnesium salts of fatty acids' on the ingredient list.
E470b sits at the unremarkable end of the additive spectrum. It is built from the same fatty acids found in butter, beef, palm oil and olive oil, combined with magnesium, a mineral present in nuts, seeds and leafy greens. The amounts used in food are small, the body recognises the components as ordinary dietary material, and the 2018 EFSA re-evaluation found nothing to add to three decades of routine approval. The science here is not contested or unsettled; the additive simply has not attracted meaningful toxicological scrutiny because there has been no signal to pursue.
No. E470b is permitted in the UK under assimilated EU Regulation 1333/2008 and appears on the UK Food Standards Agency approved-additives register. It is authorised in approximately 67 food categories.
Magnesium stearate is one specific compound within the E470b group. E470b covers magnesium salts of several fatty acids including stearic, palmitic and oleic acid. Magnesium stearate is the most common form used in food supplements and is widely used as a flow agent in tablet manufacture.
It appears most often in food supplements (tablets and capsules), powdered drink mixes, cocoa products, chewing gum, confectionery coatings and some baked goods. It is listed on the ingredient panel as E470b or 'magnesium salts of fatty acids'.
Not always. The fatty acids used in E470b can come from animal sources (tallow, lard) or plant sources (palm oil, coconut oil, soy). The origin varies by manufacturer and is not typically declared on the ingredient list. Those following a vegan diet would need to contact the manufacturer directly to confirm the source.
Last reviewed: 20 June 2026
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