Supermarkets have come a long way since a South China Morning Post reader complained to the editor 11 years ago about the lack of options for the lactose intolerant. Today, there are so many milk alternatives available that the biggest problem is deciding which one to buy.
Walk into a supermarket and you're likely to find a range of milk substitutes derived from soy, rice, almond and oats. If you're in one of the posher grocery stores, you might even find hemp and flax milk.
Bart Cheng, key account manager with Hutchison Hain Organic (HHO), a Hong Kong-based distributor of natural and organic products, says demand for its range of milk alternatives has been growing since they were introduced in the city in 2010.
The company distributes Almond Dream, Soy Dream, Rice Dream and Westsoy. Sales of its two main products, the latter two, have grown 35 per cent in the past year at ParknShop supermarkets.
Faced with so many alternatives, Shane Early, a teacher at a local girls' college, wonders: "Soy milk, rice milk, almond milk - what's the real difference? I can't do dairy milk; my stomach gets very angry."
Reactions in the stomach to dairy products are symptoms of lactose intolerance and may include flatulence, diarrhoea, a bloated feeling, pains and cramps, stomach rumbling and a general ill feeling, according to Britain's National Health Service.
"Asians are more prone to lactose intolerance," says Karen Chong Kam-leng, a registered dietitian at Matilda International Hospital.
"Some studies say it is hereditary. Northern Europeans have the lowest percentage of lactose intolerance in their populations."
In a study published in 2009 in the journal PLoS Computational Biology, researchers at University College London found that the drinking of cow's milk started about 7,500 years ago in central Europe. Continued exposure to milk caused the genetic change in Europeans that enabled them to digest the milk sugar lactose.
Today, more than 90 per cent of the population of northern Europe is lactose tolerant. So are some African and Middle Eastern populations. But that's not true of most of the global adult population.
According to a Cornell University study published in 2005 in Evolution and Human Behaviour, about 60 per cent of the global population, and primarily those of Asian and African descent, stop producing lactase, the enzyme required to digest milk, as they mature.
Mimi Li Shuk-ping, consultant dietitian at Children 818, says many Hongkongers are lactose intolerant because mothers tend to cut milk from their child's diet after they become a year old.
But this intolerance tends to be mild. "Most people can actually consume a small amount of dairy products," she says.
Intolerance can be overcome, says Chong, by introducing lactose slowly into the diet.
"For example, start with half a glass of milk first - try to have it warm, and have something with it. Do it gradually, day after day, and you can get used to it."
Some dairy products that don't have a lot of lactose, such as hard cheese and yogurt, are also good ways to start reintroducing lactose into the diet, adds Chong.
But not all adverse reactions to dairy are caused by lactose intolerance. Some people are allergic to the milk proteins, casein and whey, says Li.
Allergic reactions include runny nose, itchy eyes, dry throat, rashes, hives, nausea and diarrhoea.
There are potentially more serious complications, such as difficulty breathing and anaphylactic shock.
Hence the appeal of milk alternatives. But these products have an even wider reach. HHO's Cheng says they also attract people who have other food sensitivities, or want cheaper organic alternatives. Rice and almond milk, for example, retails for about HK$22 to HK$23 per litre, and soy milk about HK$12 to HK$14 per litre.
Organic milk can cost more than double that.
Milk alternatives, especially from plant sources, seem more appealing in the wake of tainted milk scandals that have plagued the Chinese dairy industry.
Furthermore, plant-based milk is cholesterol free, since cholesterol is found only in animal products (though there is a minimal amount in fat-free milk).
Li says advertising has boosted the popularity of milk alternatives.
"Some soy milk marketing claims milk protein is not well absorbed. A lot of my clients ask me if this is true. But there are no guidelines or research that recommends patients switch to other sources, unless you're lactose intolerant or have a milk protein allergy."
Still, more people are avoiding cow's mile. But can milk alternatives match the real deal, providing essential vitamins, minerals and other nutrients?
Milk is seen as a "complete" food. After all, it is what all babies thrive on in their first few months of life.
Cow's milk is high in protein, calcium, phosphorus, and vitamin A, D and B12. The recommended daily intake for adults is two servings (each 240ml) of low-fat or skimmed milk, says Chong.
"Calcium is the most important thing - if you want to replace dairy products, look for something that is high in calcium," she adds. "Make sure the milk alternative is fortified with or naturally high in calcium."
Li notes that milk alternatives are often fortified with vitamins and minerals. So their nutrition formulae are similar to milk.
These added nutrients are comparable to naturally occurring ones, she says.
"The body is still able to absorb the nutrients. Adding them to food is better than taking supplements alone because food has naturally existing enzymes that help with the absorption of the nutrients."
You can also supplement your calcium intake through other food sources, says Chong. These include sardines or dried small fish with edible bones; dark green leafy vegetables like choi sum and kai lan; Brazil nuts and almonds; sesame, tahini and hummus; and fortified orange juice and cereal.
If you want to try a milk alternative, here are some common options, and their pros and cons.
Soya milk A study published last year in the European Journal of Clinical Nutrition showed that soya protein compared to dairy milk protein supplementation improves the lipid profile in healthy individuals, supporting heart health.
"[Soya milk] is the first recommended alternative, but look for those fortified with calcium as soya by itself is not very high in calcium," says Chong. Soya milk contains isoflavones, a phytoestrogen thought to protect against some cancers, although it's recommended that women with oestrogen-dependent breast cancers limit soya foods. Some people with milk protein allergy might not tolerate soya milk, too.
Rice milk Most rice milk has calcium levels fortified to match dairy milk. It's also low in fat and saturated fat. Rice milk is usually unsweetened but naturally high in sugars - it's twice as sugary as soya milk on average.
Chong says the protein in rice milk is not as good as that in soya milk, which is not as viscous as the other options, although some manufacturers add oils to thicken it.
Almond milk Chong says almond milk is high in calcium. It's also naturally low in calories and saturated fat. "Because it's from a nut, it also has monounsaturated fat, which is a heart-protecting oil," says Chong.
But she adds that, like rice milk, the protein in almond milk is incomplete. You'll need complimentary foods with protein to ensure you get all the essential amino acids.
Also, most products have added sugar or syrups made from agave, cane or rice. Li adds that almond milk may not be suitable for those with nut allergies.
Oat milk Oat milk is relatively low in fat and saturated fat, and offers a moderate amount of protein. It also contains cholesterol-lowering beta glucan. Li says people with wheat allergies will not be able to stomach oat milk.
Goat's milk Goat's milk is a "natural functional food", according to a study released last year by researchers at the University of Granada in Spain. It has many nutrients that make it similar to human milk.
These include oligosaccharides, which are compounds that reach the large intestine undigested and keep the gut healthy. Goat's milk contains less of the milk protein that's responsible for most milk allergies, and a lower proportion of lactose. It also has more essential omega-6 fatty acids (linoleic and arachidonic), which have heart benefits.
Goat's milk is rich in calcium and phosphorus, and also has more zinc and selenium, which are essential micronutrients that prevent neurodegenerative diseases.