Documentary filmmaker Lee Fulkerson explores the possibility that so-called 'diseases of affluence,' such as heart disease, can be reversed by simply adjusting our diets to include less processed and animal-based foods. Back in the 1960s, Cornell University nutritional scientist Dr. T. Colin Campbell was working to find a way to feed the citizens of impoverished Third World nations when a trip to the Philippines forever changed the way he thought about food consumption. There, he discovered that the rates of liver cancer among affluent children who subsisted on diets rich in animal-based foods were notably higher than in children consuming plant-based diets. Meanwhile, surgeon Dr. Caldwell Esselstyn, head of the Breast Cancer Task Force at Cleveland Clinic, was also discovering that many of the diseases he was seeing in patients were practically non-existent in areas of the world where people were primarily consuming plant foods. Several subsequent investigations by the researchers (who would not meet each other until the 1980s), including a ground-breaking study in China by Dr. Campbell, led them to the revelation that a whole-food, plant-based diet could prevent, and even reverse, such degenerative conditions as type 2 diabetes, heart disease, and some forms of cancer. In this film, Fulkerson examines Dr. Campbell's and Dr. Esselstyn's theories by following the two doctors' individual, yet very similar, story arcs, from their farm-based upbringings to their astounding discoveries. The film also records the experiences of a group of patients suffering from chronic maladies as they participate in an experiment in which their diets are substantially altered and wholesome, plant-based food is, essentially, used as medicine
The next instalment focuses on dietary needs and how different species have evolved beaks to suit their individual requirements. The latter come in a multitude of forms. Blue tits and goldfinches have beaks akin to tweezers, with which to extract seeds, while the hawfinch's razor-like bill can deal with a cherry-stone. However, the crossbill is the only finch that can twist its mandibles in opposite directions. Jays store acorns for winter by burying them in the ground, whereas woodpeckers can keep up to 60,000 of them in one tree trunk. Sap is also desirable, and there are a variety of methods used to obtain it. The hoatzin is the only specialised leaf-eater, and accordingly has a digestive system more akin to that of cattle. Plants recruit birds to aid pollination, and offer nectar as a reward. Hummingbirds eat little else, and the sword-bill's beak is the longest of any bird in relation to its body. Insects are also highly prized, and Galapagos finches are shown to possess some ingenuity as they not only strip bark, but also use 'tools' to reach their prey. Crows are hailed as being among the most intelligent birds, and one is shown using a twig to spear a grub within a fallen log. The robin is an opportunist, and Sir Attenborough observes one seizing morsels as he digs a patch of earth. In South America, a cattle tyrant sits atop an obliging capybara and uses its vantage point to spot passing food that may be dislodged by its grazing partner.
It is time to see if personalised dieting will work in normal life. The volunteers have been given one of three diets to follow - based on their genes, their hormones and their psychology. But now they are back at home, trying to stick to their personalised diets with all the stresses and temptations of real life. Dr Chris van Tulleken and Professor Tanya Byron discover how our genetic makeup can make temptation difficult to resist, how understanding the brain reveals what makes us comfort eat and what science can tell us about why we make disastrous food choices.
So far the volunteers have successfully been losing lost weight, but now the honeymoon period is over. It is the final two months of the diet, and their minds and bodies are fighting back. Dr Chris van Tulleken and Professor Tanya Byron find out if the new personalised diets will help them stay on course, and the experts reveal the scientific secrets to permanent dieting success.
The fifth programme explores the alliances formed between the animal and plant worlds. Attenborough dives into Australia's Great Barrier Reef and contrasts the nocturnal feeding of coral, on microscopic creatures, with its daytime diet of algae. Some acacias are protected by ants, which will defend their refuge from any predator. Besides accommodation, the guards are rewarded with nectar and, from certain species, protein for their larvae as well. Fungi feed on plants but can also provide essential nutriment to saplings (Mycorrhiza). The connection is never broken throughout a tree's life and a quarter of the sugars and starches produced in its leaves is channelled back to its fungal partners. Meanwhile, fungi that feed on dead wood leave a hollow trunk, which also benefits the tree. Orchids enjoy a similar affiliation. Lichens are the product of a relationship between fungi and a photosynthetic associate, usually algae. They are extremely slow-growing, and a graveyard is the perfect location to discover their exact longevity. Mistletoe is a hemiparasite that obtains its moisture from a host tree, while using own leaves to manufacture food. Its seeds are deposited on another by the mistletoe tyrannulet, following digestion of the fruit. The dodder (Cuscuta) is also parasitic, generally favouring nettles, and siphons its nourishment through periodic 'plugs' along its stem. The rafflesia has no stem or leaves and only emerges from its host in order to bloom — and it produces the largest single flower: one metre across.
