Phytonutrients

Andrew Salter, Helen Wiseman, Gregory Tucker, Andrew Salter, Helen Wiseman, Gregory Tucker

• Publisher: Wiley-Blackwell
• Year: 2012
• Print ISBN: 9781405131513
• eBook ISBN: 9781118240922
• Edition: 1
• Topic: Technology & Engineering
• Subtopic: Food Science
• Index: Technology & Engineering

In many Western diets, the role of plants has been reduced in favour of more animal-based products and this is now being cited more widely as being the cause of increases in the incidence of diseases such as cancer and cardiovascular disease. This important book covers the biochemistry and nutritional importance of a wide range of phytonutrients, including all the major macronutrients as well as the micronutrients and 'non-essential' nutrients.

Phytonutrients is divided into three parts. The first deals with the role of plants in the human diet. Part II, representing the major part of the book covers in turn each of the major phytonutrient groups. Chapters include: non-lipid micronutrients, lipids and steroids, carotenoids, phenolics, vitamins C, E, folate/vitamin B12, phytoestrogens, other phytonutrients and minerals, and anti-nutritional factors. The final part of the book covers the methods used to manipulate levels of phytonutrients in the diet, such as fortification, supplementation and the use of genetically modified plants.

Phytonutrients is an essential purchase for nutritionists, food scientists and plant biochemists, particularly those dealing with nutrients from plants, and their use in the human diet.

Chapter 1

Plant foods and health

Judith Buttriss

Introduction

The purpose of this introductory chapter is to pave the way for subsequent chapters by looking at the historical context of plant food consumption, reviewing the contribution plant foods make to intakes of essential nutrients (e.g. fibre, vitamins, minerals, protein and essential fatty acids), examining the evidence linking plant food intake to health, summarising current recommendations and policy regarding plant food intake, and comparing these recommendations with current intakes.

Historical changes in the plant content of the human diet

Throughout human history, communities and societies have developed a diversity of dietary patterns and habits that have taken advantage of the food plants and animals available to them as a result of personal skills, climate, geography, trade and economic status. It is a basic premise the diets that persisted were capable of providing sufficient energy and essential nutrients to support growth and reproduction. They may not, however, have been conducive to optimal health.

Archaeological investigations have been used to predict what the diet of early man was like. Nestle (1999) cites Eaton and Konner (1985) who proposed that by the time of the emergence of modern Homo sapiens 45 000 years ago (Table 1.1), meat intake was high, but lean, and plant foods provided levels of vitamin C that exceed current recommendations. The diets of those modern day communities who survive primarily through hunting and gathering have also been used as a source of information, although the extent to which the diets of such communities simulate those of early man can only be speculated. Estimates suggest that most of the modern day hunter-gatherer communities lived in areas where plant foods grew readily, one exception being the indigenous people living in the Arctic whose traditional diets were dominated by meat and who relied almost completely on hunting for much of the year (Eaton and Konner 1985). Also, anthropologists have examined the diets of closely related primates for clues about the possible diets of our distant ancestors. In general, primates seem to eat whatever is convenient, mainly plants but also insects, eggs, crustaceans and carrion (Nestle 1999). Recent documentary evidence has captured film of chimpanzees and other primates hunting and killing animals as prey, which has subsequently been shown on wildlife television programmes in the UK.

Table 1.1 Stages of evolution of human diets

Adapted from Eaton and Konner (1985).

	Time period elapsed (years)
Pleistocene: Stone Age	1.6 million
Homo sapiens: Archaic	400 000
Neanderthal	80 000
Modern	45 000
Holocene: Agriculture	10 000
Industrial revolution	200
Global food economy	50

Archaeology has provided considerable evidence for meat consumption by early man, including characteristic marks on fossilised animal bones and stone artefacts consistent with meat eating. However, this information must be considered in context: bones are better preserved than vegetable matter and hence reliance on such evidence is likely to underestimate plant food consumption (Nestle 1999).

Plant foods can be categorised in many ways but the method used here can be seen in Table 1.2. It has been suggested that the plant foods gathered by our early ancestors were those that did not require digging with hands or sticks, such as fruits, leaves and stems, and seeds in pod-like structures (e.g. peas, beans) that would have provided protein. There is also early evidence of the cultivation and storage of legumes such as broad beans in the Middle East, where ‘farming’ is said to have begun, and among cave dwellers living as far apart as Mexico and Peru, and north-east Thailand (Toussaint-Samat 1992). Similar evidence exists for collection of wild chick peas, lentils and peas, followed by their cultivation.

Table 1.2 Categorisation of plant derived foods and drinks

From Buttriss 2003.

Group	Examples
Fruits
Tree Fruits	Apples, pears, plums, apricots, peaches, cherries, citrus fruit, dates, pineapple, mango, papaya, fig, olive
Soft fruits	Strawberries, raspberries, blackberries, cranberries, currants
Other	Melons, grapes, kiwi, bananas
Vegetables
Root crops*	Potatoes, sweet potatoes, yam, cassava Carrots, turnips, swedes, parsnips
Cabbage family	Cabbage, broccoli, Brussels sprouts
Onion family	Onions, leeks, garlic
Salad vegetables	Lettuce, celery, cucumbers
Tomato family	Tomatoes, sweet peppers, chilli peppers, aubergine
Mushrooms and fungi	Mushroom varieties, Quorn™
Other	Squashes, sprouted seeds, sea vegetables
Cereals (grains)	Wheat, barley, maize (corn), millet, oats, rice, rye
Tree nuts and seeds	Walnuts, cashews, almonds, chestnuts, pecans, brazils, hazelnuts, pistachio, pine kernels, sesame seeds, pumpkin seeds
Pulses (legumes)	Soya beans and products e.g. tofu, red kidney beans, butter beans, chick peas, lentils, peanuts (groundnuts)
Beverages	Tea, coffee, cocoa, wine, spirits, beer
Oils	Seed oils e.g. sunflower oil, corn oil, rapeseed oil, linseed oil; olive oil, soya oil, peanut oil; evening primrose oil, borage oil
Other	Chocolate
Herbs, spices, condiments	Sage, rosemary, thyme, ginger, pepper, cumin, mustard, tomato-based sauces

*Potato, sweet potato and yam are classified as starchy foods, rather than vegetables, in many food guidance models.

In hot, humid areas where top soil is poor, root systems grow near to the surface and will have been easy to forage. In more temperate climates, such as the Middle East, a stick or similar pointed implement would probably have been required and its use was perhaps the first step towards farming. The digging stick is thought to have been the ancestor of the hoe and the plough (Toussaint-Samat 1992). Roots and tubers, gathered or cultivated, have been a dietary staple in tropical zones since early times, providing energy and being easy to acquire. A limited number are popular now but many other examples exist in nature. The sweet potato, for example, comes from the equatorial forests of South America but is thought to have reached Polynesia 2000 years ago, perhaps via early trade (Toussaint-Samat 1992). The potato and sweet potato reached the shores of Europe as part of a present to Queen Isabella of Spain from Christopher Columbus. The potato itself was not popular and had to wait until the eighteenth century before it came into its own, but the versatile sweet potato was a success in Elizabethan England, perhaps because of its sweet taste at a time when sugar was scarce and very expensive (Toussaint-Samat 1992). Following the example of the native Indians in North America, European colonists made sweet potato one of their national dishes. The Jerusalem artichoke, another tuber, is also well travelled. It was found growing wild in North America and transported across the Atlantic in the seventeenth century and is said to be the only food plant that has been introduced to Europe from North America (Toussaint-Samat 1992). The yam, of a different botanical family to the sweet potato, grows naturally in tropical forests all over the world and is relatively rich in protein. Tapioca, a popular milk pudding ingredient in the recent past, is derived from cassava. The cassava shrub is protected from parasites by the cyanide compounds (prussic acid) it contains in the skin of its tubers, which need to be carefully prepared before consumption because even a tiny quantity of the bitter cassava juice causes instant death. The complex methods for its preparation must presumably have been identified by trial and error among people with very limited dietary options.

There is also early evidence of the consumption of onions, which have the advantage that they can be eaten raw. They grow wild in a large part of the Middle East and the Indian subcontinent, and it is suggested they were used to relieve the monotony of frugal diets. Labourers working on the Great Pyramid were paid in onions, garlic and parsley, and onions accompanied Egyptian mummies into their tombs (Toussaint-Samat 1992). The onion has been widely used over the centuries and was taken on long sea voyages in the hope that it might prevent scurvy. Garlic, also a member of the allium family, is thought to have come from a desert area of Central Asia and is surrounded by a remarkably rich and ancient body of folklore.

The discovery and study of Palaeolithic refuse tips has been facilitated because grains found there were preserved from the ravages of time by carbonisation (parching) during their processing to remove the inedible husk. This primitive form of ‘cooking’ in stone age culture remained in use in the Middle Ages (Toussaint-Samat 1992). Perhaps the development of such techniques and the identification of areas where wild cereals grew in abundance or could be cultivated were triggers for people to become ‘settled’ in one place rather than living a more nomadic life, thus experiencing a less tenuous lifestyle and greater life expectancy. Early evidence shows that initially the cereals cultivated were identical to the wild types, but even as early as 10 000 BC there is evidence from Jericho of selection of the forms of barley and wheat that less readily shed their seed on ripening, allowing it to be harvested more effectively. Indeed there is evidence from all around the world of early cereal cultivation thousands of years ago, for example in the Dordogne in France in 8000 BC, Japan in 7500 BC, Mexico in 6000 BC, Denmark, China and Siberia in 4000 BC, and India in 3000 BC. By AD 100, rye and oat cultivation was widespread across Europe, joining wheat which had been in cultivation in many parts of Europe for some time (Toussaint-Samat 1992). The spread of cereal growing provides information about the migration of the people who consumed it, as they took their customs with them.

The most commonly consumed cereal grains in the human diet are wheat, rice and maize, although barley, oats, rye, millet and sorghum are more common in some countries than others, consumption patterns being largely determined by climate and cultural differences (Southgate 2000).

Current dietary patterns in developed countries have been largely shaped by the changes in food production that began with the industrial revolution during the 1800s. These dietary patterns have been fuelled by a global food economy in which food is now transported long distances, enabling a diverse range of plant foods to be available in shops all year round and removing the dependency on local, seasonal produce.

In developing countries in the twenty-first century, plant-based diets are associated with extreme poverty and poor health...

Table of contents

• Cover
• Title page
• Copyright page
• Preface
• Contributors
• Abbreviations
• Chapter 1: Plant foods and health
• Chapter 2: Carbohydrates and lipids
• Chapter 3: Carotenoids
• Chapter 4: Polyphenols
• Chapter 5: Vitamins C and E
• Chapter 6: Folate
• Chapter 7: Phytoestrogens
• Chapter 8: Plant minerals
• Plates
• Index