What is the best diet to follow and foods to eat to regain or maintain optimum health? The equivalent of the Brazilian rain forest has probably been leveled to paper the books attempting to answer just that question.

But confusion still abounds. Should you go Paleo or vegan when you are ill? And what are the best foods to prevent or heal cancer?

To find out, you need to take a tip from bears – and monkeys, and rats and most of the animal kingdom.

After witnessing sick bears eating the roots of Ligusticum plants and getting better afterwards, North American Native Americans gave the plants a name, which means ‘bear medicine.’

Most conventional scientists have disparaged anecdotes such as these, putting them down to myth—until recently. Animal behaviorists have discovered that animals do indeed appear to have a natural instinct, across species, for determining which plants can be used to stay healthy or heal different diseases.

Animal behaviorist Dr Cindy Engel spent years gathering scientific evidence that animals self-medicate, much of which she poured into her book Wild Health (Houghton Mifflin). In her research, Engel discovered that animals instinctively know how to maintain optimum health.

Given a smorgasbord of choice, animals like rats, for instance, will choose a nutritionally balanced diet. A number of animals even know to make compensatory choices when the food supply changes with the season.

For instance, she says, deer graze in summer on grass, but switch to ivy and holly when the grass dies back. Similarly, when the energy content of food drops in winter, animals like the Madagascar primates aye-ayes will double their intake; before droughts, camels and rhinos will switch to eating foods rich in salts and water.

What is also remarkable, however, among all species, is their instinctive sense of impending extraordinary nutritional needs. Animals like birds and squirrels will change the fat content in their diets before migration and hibernation, respectively. And when their nutritional needs increase, such as during pregnancy, they increase their consumption of mineral-rich foods.

When moose and deer need to grow antlers, their bodies raid the calcium and phosphorus from their bones to feed.

The animals would then develop osteoporosis if their diets weren’t extraordinarily mineral-rich and because soils are often so depleted of these minerals, the animals will resort to chewing on cast-off antlers or chew soil from around decomposing bones or eat salty fish.

Numerous other studies show that many vegetarians among the deer family become carnivorous when necessary, and animals that are ordinarily conservative in their diet will become more adventurous when deprived of a particular nutrient.

Perhaps more extraordinary is evidence suggesting that animals know how to self-medicate against parasites, infection, skin conditions and poisons. Engel’s research shows that animals have learned which substances—such as clay, soil and charcoal—can absorb and neutralize particular plant toxins.

They understand how to deal with certain pathogens—either by increasing body temperature or, in the case of the honeybee, by coating the hive with propolis, a potent antimicrobial.

Engel has also uncovered ample evidence that animals rub bioactive compounds into their fur or skin to discourage unwanted insects, ticks and mites.

The American evolutionary ecologist and conservationist Daniel Janzen began collating evidence that animals somehow are able to differentiate the thousands of toxic secondary compounds in plants that kill internal parasites. For instance, a number of species, including rhinoceros and wild bison, feast on a certain bark known to be toxic to the microbes that cause dysentery.

Even animals in captivity often have a native sense of self-medication superior to their doctors. In one instance, a captive capuchin monkey that had a severe skin infection did not get better until it was given access to tobacco leaves (which contain nicotine, a potent toxin). Rubbing the leaves on the affected area cured the skin condition permanently.

Although animals are supremely good at using food and natural substances to heal, humans seem to have lost that instinctive sense of what is good to eat even to maintain optimum health.

Hundreds of superfoods fit for humans contain extraordinary substances that can prevent or heal a vast number of diseases. Just four teaspoons of mushrooms a day can nearly halve your chances of getting cancer and also cut your chances of suffering from depression, for instance.

Avocados contain a substance called avocation B, which both prevents diabetes type 2, helps you lose fat around the middle and even prevents leukemia. Green leafy vegetables have been demonstrated to keep your brain sharp and your muscles strong into old age.

Conventional medicine is often peerless when it comes to emergency or acute medicine, but fails miserably, in the main, when solving most chronic illness.

Natural substances, on the other hand, contain complex, synergistic healing compounds that even the most sophisticated drug cannot mimic.

Given their natural instinct for the healthy, one wonders what animals would make of the tendency of their human cousins to consume toxic junk as food and toxic chemicals as medicine.

To stay strong and healthy in 2022, the answer is simple: take a leaf out of the playbook of monkeys. Eat organic, whole foods, cook from scratch and listen more closely to your own gut hunches about what you need to eat in order to get and stay well.