So what is so special about this product?

Respected nutritionist Rosemary Stanton told Fairfax Media that there are very strict guidelines about what has to go in and what can't go in baby formula.

Dr Stanton said: "I can't see anything special other than its ingredients are organic."

Much to her surprise, the Bellamy's product that is hardest to get is toddlers' milk, for babies 12 months and older.

"That's totally ridiculous," she said. "There is no reason why a child over 12 months can't have regular milk".

Infant formula for babies up to 12 months old tries to mimic breast milk, which is mostly proteins, lactose and fats along with vitamins, minerals and enzymes.

Breast milk has everything a baby needs for the first six months of life. However, some parents and caregivers are either unable or unwilling to breastfeed for that period of time, or use formula to supplement breast milk.

The NSW Department of Health says that infant formula is the only safe alternative to breast milk in the first year of life.

"Unless there are good reasons you can't, if you're really worried about getting the best for baby, nothing beats breastfeeding," Dr Stanton said.

There are strict standards in Australia about the composition of infant formula. Jan Carey, chief executive of the Infant Nutrition Council, which represents formula manufacturers, told Fairfax Media that baby formula is "the most regulated food product on the market".

The bulk of infant formula is whey powder, combined with a mixture of lactose, casein proteins, milk solids, vegetable oils, vitamins, minerals and biosynthetic enzymes.

Ben Lovitt, a marketing officer at Bellamy's Organic, said the mixture changes slightly from infant to follow-on and toddlers' formula, with the formula for older babies having more casein.

Whey is the protein by-product of cheese production from cow's milk. Think Little Miss Muffet and her curds and whey. Curd becomes cheese, whey is liquid leftover. Casein is a milk protein.

The second biggest component of formula is typically oils and fatty acids. Some dairy fats are unsuitable for babies and are removed, so lactose powder is included, without the dairy fats. However, fat content is very important for babies and is replaced by various vegetable oils.

The rest of infant formula is a mix of synthetic enzymes, vitamins and minerals, all strictly regulated by Food Standard 2.9.1.

In Australia and New Zealand, infant formula is required to have specific levels of proteins, fats, vitamins, minerals, and electrolytes.

Food Standards of Australia and New Zealand standard 2.9.1 covers infant formula products.

Its 22-pages are very specific.

Infant formula must have an energy content of no less than 2500 kilojoules a litre and no more than 3150 kilojoules a litre. It must also have a minimum of 0.45 grams of protein for every 100 kilojoules of energy.

The document is very technical: it states that Inosine 5'-monophosphate​ must be in formula at least 0.08 milligrams but no more than 0.24 milligrams per 100 kilojoules. It can only appear in the form of Inosine 5'-monophosphate or Inosine 5'-monophosphate sodium salt. It is a biosynthetic enzyme important for cellular growth.

CHINESE DEMAND

Demand for foreign infant formula has risen in China since 2008, when a Chinese infant formula was contaminated with melamine. Photo: The New York Times

The "white gold rush" for Bellamy's Organic formula from buyers in China seems to be as much about making sure babies have (second) best as it is about ongoing fears about the safety of Chinese formula. In 2004, about 50 babies were thought to have died from being fed fake infant formula in Anhui province in China. The formula did not contain adequate levels of protein.

In another baby milk scandal, in 2008, more than 15,000 infants needed hospital treatment and six died when formula was found to contain melamine. Melamine is a toxic organic compound that can lead to the development of kidney stones and renal failure in babies.

There are ongoing concerns about contamination of dairy products in China. In 2010, 64 tonnes of dairy products were seized when they were found to contain melamine.

In 2013, China banned milk powder and infant formula from New Zealand after Fonterra recalled a product that had contaminated whey products.

Marketers in China have taken full advantage of these concerns, which has proved a boon for Australian companies. Blackmore's share price has surged since it reached a deal with Bega Cheese to produce infant formula for Chinese markets.

• An earlier version of this story described Bellamy's Organic milk for over-12 months as "follow-on milk". It is in fact "toddlers' milk". Fairfax Media is happy to correct this.