A lot of the additives like E numbers, used as colorants etc are frequently derived from animals and animal by products. Some are of questionable origin and thus safer to avoid.

red - animal origin

blue - possible animal origin 

e120

Cochineal, Carminic acid, Carmines Natural Red 4 - colouring

A colouring that makes many foods red. Found in alcoholic drinks, fruit pie fillings, jams, many sweets and even cheeses. Cochineal is made from the female insect found on cacti called Dactylopius Coccus. She is boiled alive or left to "cook" alive through sun exposure. Cochineal is the result of crushing scales of the insect into a red powder.

e153

Carbon Black, Vegetable Carbons - colouring

If the description on product packaging says "Vegetable Carbons", then it is most likely free of animal derivatives. (but could be derived from GM crops) But if the additive is described as "Carbon Black", it 's more likely to be derived from various parts of animals.

e161g

Canthaxanthin (Natural Orange Colour Xanthophylls) - colouring.

Be aware that although Canthaxanthin is usually derived from plant material, it can sometimes be made from fish and invertebrates with hard shells.

e252

Potassium Nitrate (Saltpetre) - Preservative

Saltpetre is usually assumed to be of natural origins but it can be artificially manufactured from waste animal matter.

e270

Lactic Acid - Antioxidant

Can be obtained from whey. Lactic Acid can be found in carbonated drinks, beer, dressings and various tinned products.

e322

Lecithins - Emulsifier and Stabilizer

Some Lecithin contains egg yolks. Other main sources of Lecithin are from soya bean oil and is likely to be genetically modified (if sourced from countries such as the US) Lecithin can also be directly obtained from animal fat.

e325

Sodium Lactate - Antioxidant

Sodium Lactate is the salt of Lactic Acid. (see E270 above)

e326

Potassium Lactate - Antioxidant / Acidity Regulato r

Another type of salt derived from Lactic Acid. (see E270 above)

e327

Calcium Lactate - Antioxidant

Another type of salt derived from Lactic Acid. (see E270 above)

e422

Glycerol (Humectant, Solvent, Sweet Glycerin) - Sweetener

There is contention surrounding the origins of Glycerol. Through various industrial reselling practices, a majority of glycerine originates as a by-product of soap manufacturing. Many soaps are manufactured using animal fats. This indicates that even though glycerine occurs naturally in plants, what ends up in food and soap products mostly originates from animals.

e430 - 436

Polyoxyethylene - Emulsifiers and Stabilisers

E numbers 430 to 436 are various types of polyoxyethlene:

E430 Polyoxyethylene (8) stearate (Emulsifier / Stabiliser)
E431 Polyoxyethylene (40) stearate (Emulsifier)
E432 Polyoxyethylene (20) sorbitan monolaurate (polysorbate 20 Emulsifier)
E433 Polyoxyethylene (20) sorbitan monooleate (polysorbate 80 Emulsifier)
E434 Polyoxyethylene (20) sorbitan monopalmitate (polysorbate 40 Emulsifier)
E435 Polyoxyethylene (20) sorbitan monostearate (polysorbate 60 Emulsifier)
E436 Polyoxyethylene (20) sorbitan tristearate (polysorbate 65 Emulsifier)

These additives are very unlikely to originate from animals as they are normally derived from various types of fruit. It may still be worth checking with manufactures as to the exact origins of the ingredients which make up these Emulsifiers and stabilisers.

e441

Gelatine - Emulsifier / Gelling Agent

You may not find this E number 441 on food ingredients listings anymore because instead of an additive, Gelatine has now been classed as food (made of animal skin and hoofs) in it's own right. Remember, all types of gelatine are animal based.

e442

Ammonium phosphatides - Emulsifier

Amonium phosphatides can sometimes be made using Glycerol (see 422 above) Therefore the finished additive may contain animal fat.

e470a

Sodium, potassium and calcium salts of fatty acids - Emulsifier / Anti-caking Agent

As 470 is derived from fatty acids, these may originate from animal sources.

e470b

Magnesium Stearate - Emulsifier / Anti-caking Agent

This is another magnesium salt from fatty acids and like 470a, may originate from animal sources

 
e471

Mono- and Diglycerides of fatty acids (glyceryl monostearate, glyceryl distearate) - Emulsifie r

Because E471 is derived from Glycerine (Glycerol) (see E422 above), there may be a slim chance that E471 might contain animal fats.

e472 a - f

E472 A to F are emulsifiers related to the mono- and diglycerides of fatty acids family:

E472a Acetic acid esters
E472b Lactic acid esters
E472c Citric acid esters
E472d Tartaric acid esters
E472e Mono- and diacetyl tartaric acid esters
E472f Mixed acetic and tartaric acid esters

Because the E472 family is derived from Glycerine (Glycerol) (see E422 above), there may be a slim chance that any of these might contain animal fats.

e473

Sucrose esters of fatty acids - Emulsifier

E473 is a sucrose ester of E471, being fatty acids, which may be derived from animals.

e474

Sucroglyceride - Emulsifier

E474 is a glyceride of sucrose ester of E471, being fatty acids, which may be derived from animals.

e475

Polyglycerol esters of fatty acids - Emulsifier

Being an ester of fatty acids which may be derived from animals.

e476

Polyglycerol Polyricinoleate - Emulsifier

As this is produced from glycol esters the glycerol can be sourced from a by-product of animal fats in the manufacturing of soap.

e477

Propane-1, 2-diol esters of fatty acids, propylene glycol esters of fatty acids - Emulsifier

The glycol esters of fatty acids can be sourced from a by-product of animal fats in the manufacturing of soap.

e478

Lactylated fatty acid esters of glycerol and propane-1 - Emulsifier

See 477 above

e479b

Thermally oxidized soya bean oil interacted with mono- and diglycerides of fatty acids - Emulsifie r

See 471 above

e481

Sodium Stearoyl-2-lactylate - Emulsifier

See 471 above and 270 (contains Lactic Acid and Stearic Acid)

e482

Calcium Stearoyl-2-lactylate - Emulsifier

See 471 above and 270 (contains Lactic Acid and Stearic Acid)

e483

Stearyl tartrate - Emulsifier

See 471 above

e491

Sorbitan monostearate - Emulsifier and Stabilizer

From stearic acid and is used in dried yeast. Stearic acid is found in vegetable and animal fats, but commercial production is usually synthetic. See also 570

e492

Sorbitan Tristearate - Emulsifier

See 491

e493

Sorbitan Monolaurate - Emulsifier

See 491

e494

Sorbitan Monooleate - Emulsifier

See 491

e495

Sorbitan Monopalmitate - Emulsifier

See 491

e542

Bone phosphate - Anti-caking agent

e570

Stearic Acid Fatty Acid - Anti-caking agent

Stearic acid is found in vegetable and animal fats, but commercial production is usually synthetic. Often used in dried yeast.

e572

Magnesium stearate, calcium stearate - Emulsifier and Anti-caking agent

See Stearic Acid 570

e585

Ferrous lactate - Colouring

A lactate is a compound formed when a mineral is bound to lactic acid. This is why additives named as a lactate may have been derived from an animal source such as whey. (see 270)

e631

Disodium inosinate - Flavour enhancer

Almost always made from animals and fish

e635

Disodium 5'-ribonucleotides - Flavour enhancer

Often made from animals

e640

Glycine and its sodium salt - Flavour enhancer

Can sometimes be prepared from gelatine.

e901

Beeswax - white and yellow - Glazing Agent

e904

Shellac - Glazing Agent

Shellac is a resin secreted by an insect called the lac bug Laccifer lacca Kerr (Coccidae) . It is often unclear as to whether the insect is killed in the process of commercially obtaining shellac as the resin is left by the insect on various plants. Whether this resin is harvested as a residue or extracted by directly killing the insects needs further investigation.

e910

L-cysteine - Improving agent

Produced commercially from animal and human hair (and feathers). When produced from animal hair it is almost certain that all L-cysteine is taken from slaughtered animals. When human hair is used it is often sourced from women in third-world countries. L-cysteine is used as an additive in around 5% of bread and other bakery products. It is not used in wholemeal bread or other wholemeal bakery products.

e920

L-cysteine hydrochloride - Improving agent

Produced from L-cystine (see 910 above)

e921

L-cysteine hydrochloride monohydrate - Improving agent

Produced from L-cystine (see 910 above)

e966

Lactitol - Sweetener

Derived from Lactose, commercially prepared using whey