Macadamia Nut

The Australian commercial native

Of the thousands of food crops we eat, almost none originated in Australia. The continent’s harsh rainfall patterns and ancient soils didn’t produce many commercially viable native foods — until the macadamia. The two species (M. integrifolia and M. tetraphylla) come from rainforests in Queensland and northern New South Wales, where Aboriginal peoples ate them long before European arrival.

Commercial cultivation began in Hawaii in the 1920s, not Australia, and Hawaii dominated production for decades. Australia overtook Hawaii by the 1990s and now leads global production.

The hardest shell

Macadamia shells have a Mohs hardness of around 4 — harder than the shells of any other commercially eaten nut. Cracking them at home is nearly impossible without a special vise; commercial processing uses high-pressure rollers. The shells are too tough for typical squirrels and most other rainforest seed predators — only powerful-jawed cockatoos and rats can break them in the wild.

A high-fat profile

At 76% fat by weight, macadamias are among the fattiest commonly-eaten foods — comparable to butter. Most of the fat is monounsaturated (similar profile to olive oil), which has earned macadamias a reputation as “heart-healthy” despite the calorie density.

Hawaiian chocolate-covered

Hawaii built an industry around macadamia nut chocolates — Mauna Loa, Hawaiian Host, and others — that became Hawaii-tourist mass-market candy. Macadamia ice cream and the famous Hawaiian “Macadamia Nut Cookies” are tied to the same tradition.

Toxic to dogs

A poorly-understood but real toxicity: macadamia nuts are toxic to dogs, causing weakness, vomiting, and tremors — usually self-limiting but distressing. The exact mechanism isn’t known. Keep macadamias well away from dogs.