Nutrition (26 page)
Juices can be used to make tasty soups, sauces, drinks or cocktails. Lemonade made by mixing a juiced lemon (plus peel) with sparkling mineral water and a touch of honey is particularly refreshing.
When buying fruit and vegetables to juice, make sure they’re garden-fresh – as soon as they’re harvested, fruit and vegetables start to deteriorate and their vitamin content drops. If possible, go for organic ingredients that have not come into contact with artificial fertilizers or pesticides. Choose firm, plump produce with a good colour, not mouldy or squidgy ones or those starting to dry out.
Citrus fruit with tough skins need to be peeled before juicing – but you can process young, unwaxed lemons and limes intact for extra flavour. Choose seedless grapes and remove the stalks to avoid bitter flavours. Some fruits, such as bananas and avocados, are difficult for juicers to cope with – they are best mashed or blended and then stirred into other fruit-juice bases instead.
Virtually any blend of fruit, vegetable or herb is possible – experiment, and vary the quantities to suit your taste. Try diluting juices with mineral water for a thirst-quenching drink. Milk and probiotic yogurt can also be added to smoothies.
Experiment with unusual mixes such as orange and strawberry; apple and fig; blueberry and pomegranate; grape and mango; carrot and watercress; beetroot and tomato; avocado, carrot and orange; spinach, tomato and celery; tomato, basil and garlic. This variety will provide a wide range of nutrients and broaden your taste buds’ experience.
DRIED FRUITS
Although fresh fruit has a low glycaemic load, dried fruits have a concentrated sugar content that gives them a high GL value – in fact, dried figs and dates contain more than 50 per cent sugar. Two or three dried figs or dates therefore make an excellent energy-rich snack, but don’t overindulge.
Green leafy vegetables are good sources of vitamin C, carotenoids, folate, fibre, calcium, magnesium, potassium, iron, manganese and selenium (if grown in selenium-rich soils). The iron present in spinach, curly kale and other vegetables is in the nonhaem form, which is not so well absorbed as the haem-form iron found in meat. However, the vitamin C present in these green leafy vegetables helps to keep the inorganic form of iron in the ferrous state which, as we have seen, allows for maximum absorption.
Broccoli is one of the most beneficial green vegetables, as it contains a number of protective phytochemicals such as sulphoraphane and the phytoestrogen genistein. Green leafy vegetables and broccoli should be steamed or briefly boiled or stir-fried to help preserve their beneficial nutrients. They can also be eaten raw in salads for optimum nutritional value. Broccoli sprouts are an exceptionally rich source of these phytochemicals and are delicious eaten raw.
Root vegetables
Many people eat just a few types of root vegetable – potatoes, carrots and parsnips, for example. Try to broaden your range, as many less commonly eaten tubers contain a granular form of starch that is more resistant to intestinal enzymes, and therefore has less impact on your blood glucose levels. This ‘resistant’ starch delivers similar benefits to soluble and insoluble fibre. Jerusalem artichokes, for example, contain an indigestible complex sugar called inulin, which is made up of units of the sugar fructose. This inulin content helps to stabilize glucose levels and is particularly beneficial when combined with foods providing a high glycaemic load. Inulin is also broken down to form fructo-oligo-saccharides, which have a prebiotic effect in the large bowel (see
Chapter 6
). Similarly, sweet potatoes are orange-fleshed tubers that have a medium glycaemic load rather than the high GL of normal, starchy white potatoes. Sweet potatoes are also a rich source of carotenoids and phytoestrogens.
Chapter 6
). Similarly, sweet potatoes are orange-fleshed tubers that have a medium glycaemic load rather than the high GL of normal, starchy white potatoes. Sweet potatoes are also a rich source of carotenoids and phytoestrogens.
ORAC scores
Many researchers now believe that coronary heart disease is not so much linked to a high saturated-fat intake but to a lack of dietary antioxidants, which protect circulating fats from oxidation. It is only oxidized LDL-cholesterol that is attacked by circulating scavenger cells and taken into artery walls, where they contribute to the hardening and furring-up process known as atherosclerosis.
Fruit and vegetables are the main dietary source of antioxidants, which include many phytochemicals plus vitamins C and E. Their antioxidant potential can be assessed by measuring their ORAC (Oxygen Radical Absorbance Capacity) score.
HOW THE ORAC TEST WORKS
The ORAC test measures how well the antioxidants in a food prevent the breakdown of a chemical (fluorescein) after it is mixed with a strongly oxidant substance (peroxyl radical). Fluorescein is used because it is luminescent, and the intensity of light it emits decreases as it breaks down. This provides an easy measure of how much fluorescein remains intact at set intervals after mixing the fruit or vegetable extract with the oxidant. A food with a low ORAC value provides little protection and the mixture’s luminosity rapidly decreases. A food with a high ORAC value protects the fluorescein from degradation and the sample remains luminescent for longer. By measuring the intensity of fluorescence in the mixture every 35 minutes after adding the oxidant, scientists develop graphs that are compared with the results from different concentrations of a standard antioxidant related to vitamin E (trolox). The final results are given as ‘trolox equivalents’ or TE. For example, pecan nuts have a high total antioxidant capacity of 179.4 micromol of TE per gram, or 17,940 per 100 g.
Based on surveys of food intake in the US, scientists estimate that the average person obtains around 5,700 ORAC units per day. The optimum ORAC intake is unknown, but it is generally agreed that you need at least 7,000 ORAC units for health, and that intakes of 20,000 ORAC units per day or more are likely to offer greater long-term health benefits.
Table 13
shows the ORAC score of selected fruit and vegetables.
Table 13
shows the ORAC score of selected fruit and vegetables.
The fruit and vegetables you select therefore have a major impact on your antioxidant intake. If you select five servings made up of blueberries, black plums, pomegranate, blackberries and a red apple, you can obtain over 40,000 ORAC units in a single day. But if your five servings comprise a banana, slice of watermelon, lettuce, cauliflower plus a tomato and cucumber salad, you would obtain little more than 2,000 ORAC units – even though you met the recommended five-a-day requirement.
Balancing your intake of foods with high, medium and low ORAC scores can optimize the antioxidant potential of your diet. The higher a fruit or vegetable’s ORAC score, the higher its ability to neutralize free radicals (the molecular fragments that damage cells through a chemical process known as oxidation).
Fruit/vegetable | ORAC score * per average serving |
Dark chocolate cocoa solids | 41,588 |
Low-bush blueberries | 13,427 |
Pomegranate | 10,500 |
Cranberries | 8,983 |
Blackberries | 7,701 |
Prunes | 7,291 |
Raspberries | 6,058 |
Red Delicious apple | 5,900 |
Golden Delicious apple | 3,685 |
Lemons/limes | 3,378 |
Oranges (navel) | 2,540 |
Red grapes | 2,016 |
Green grapes | 1,789 |
Banana | 1,037 |
Tomatoes | 415 |
Cauliflower | 324 |
Iceberg lettuce | 144 |
Cucumber | 60 |
*
ORAC score = micromol of TE.
ORAC score = micromol of TE.
As well as supplying antioxidants, fruit and vegetables provide other important phytochemicals and nutrients including vitamins, minerals, trace elements and fibre. Ideally, the majority of the five to ten servings of fruit and vegetables you eat per day (e.g. three out of five, or seven out of ten) should be in the form of vegetables rather than fruit, even though vegetables tend to have a lower ORAC score. This is because vegetables tend to contain less water, so are a more concentrated source of nutrients, and less sugar as well as more fibre.
A number of herbs and spices have a surprisingly high ORAC score, too, even though you only eat them in small amounts. The following table gives their ORAC values per gram – not per 100 g as in the table above. Adding just one gram of black pepper to a meal gives you an additional 301 ORAC units, while a gram of cinnamon supplies 2,675 ORAC units.
Use the antioxidant-rich herbs and spices shown in
Table 14
to replace salt for added flavour and nutritional value.
Table 14
to replace salt for added flavour and nutritional value.
Spice/herb | ORAC score * per gram |
Cloves | 3,144 |
Cinnamon | 2,675 |
Oregano | 2,001 |
Turmeric | 1,592 |
Nutmeg | 1,572 |
Parsley | 743 |
Saffron | 530 |
Curry powder | 485 |
Black peppercorns | 301 |
Ginger powder | 288 |
Thyme | 274 |
Chilli powder | 236 |
Mint | 139 |
Garlic | 54 |
*
ORAC score = micromol of TE.
ORAC score = micromol of TE.
Pulses
Pulses, also known as beans or legumes, are plant seeds of varying size, shape and colour that are harvested within a pod. They may be eaten fresh, or dried and reconstituted by soaking in water before cooking and eating. In agricultural terms, though, the word ‘pulse’ tends to be reserved for crops harvested for use as a dry seed. This excludes green beans and green peas, which are considered vegetable crops. Some classifications also exclude crops grown for oil extraction such as soybeans and peanuts – even though both are seeds extracted from a pod and therefore would normally be classified as a legume (in which seeds form in a pod, for example peas, beans). In practical terms, peanuts eaten as a snack food, rather than used to extract groundnut oil, are usually considered along with nuts, as in the section below.
Pulses are a good source of vitamins and minerals (especially potassium, calcium, magnesium, iron and zinc) as well as trace elements. Although almost a fifth of their energy content is in the form of carbohydrate, it is in a complex, slowly digested form, and so they have a low glycaemic load.
Within the food pyramid, pulses can be counted as part of the vegetables group and consumed frequently – several portions per week as a vegetable selection. They can also be counted as a protein source as part of the meat, poultry, fish, dry beans, eggs and nuts group. This is because pulses are a good source of protein of comparable nutritional value to fish, poultry and meat. Most pulses except soy, however, lack some essential amino acids. Chickpeas and other pulses are therefore best combined with other plant foods and wholegrains such as brown rice and wholemeal bread to provide a balanced amino acid intake. As a general rule, vegetarians can obtain a balanced protein intake by eating a combination of five parts rice to one part beans. Pulses are also a rich source of phytochemicals, especially isoflavones and other antioxidants that give them a high ORAC score, as shown in
Table 15
.
Table 15
.
Soybeans
are an excellent source of protein, which is comparable in its amino acid content to meat. They are also a good source of calcium, potassium, magnesium, iron, zinc, manganese, B-group vitamins, folate and selenium. Soy and soy products such as tofu, miso and soy milk also provide additional health benefits in the form of isoflavone phytoestrogens (genistein, daidzein and glycitein). A diet that is low in saturated fat and cholesterol, and which includes 25 g soy protein per day, can significantly reduce the risk of coronary heart disease. As a guide, 60 g of soy protein provides 45 mg isoflavones, which is one of the reasons why populations with high intakes, such as Japan, have an unusually low risk of heart attack.
are an excellent source of protein, which is comparable in its amino acid content to meat. They are also a good source of calcium, potassium, magnesium, iron, zinc, manganese, B-group vitamins, folate and selenium. Soy and soy products such as tofu, miso and soy milk also provide additional health benefits in the form of isoflavone phytoestrogens (genistein, daidzein and glycitein). A diet that is low in saturated fat and cholesterol, and which includes 25 g soy protein per day, can significantly reduce the risk of coronary heart disease. As a guide, 60 g of soy protein provides 45 mg isoflavones, which is one of the reasons why populations with high intakes, such as Japan, have an unusually low risk of heart attack.
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