Nutrition (27 page)

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Authors: Sarah Brewer

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BOOK: Nutrition
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Pulses
ORAC score
*
per average serving
Red kidney beans
13,259
Pinto beans
11,864
Red lentils
 7,325
Soybeans
 5,764
Black beans
 4,181
Chickpeas (garbanzo)
 3,022
Navy beans
 2,573
Black-eyed peas
 2,258
*
ORAC score = micromol of TE.
Lentils
are a good source of phytoestrogen lignans, and contain useful amounts of isoflavones. They also contain beneficial amounts of potassium, magnesium, iron, copper, zinc, selenium and B-group vitamins.
Red kidney beans
have an exceptionally high ORAC score due largely to their antioxidant pigments. However, they must be boiled rapidly for at least 15 minutes, then simmered until thoroughly cooked. This denatures substances (lectins) which can otherwise lead to indigestion and symptoms similar to food poisoning. Soaking beans overnight reduces cooking times, and also helps to deactivate the indigestible sugars that are fermented by bacteria to produce intestinal wind. Kidney beans provide twice as much fibre as green beans. They are also a good source of potassium and contain useful amounts of folate, calcium, magnesium, iron, zinc and selenium.
Nuts and seeds
Nuts are the edible kernels of hard-shelled seeds. These, and edible plant seeds with softer shells, supply a concentrated source of energy which is mostly supplied in the form of fat and protein and means that they have a low glycaemic index. They are also a good source of fibre, typically providing around 6 g fibre per 100 g.
The types of fats found in nuts are nutritionally valuable oils containing a high percentage of beneficial monounsaturated and polyunsaturated essential fatty acids. For example, macadamianut oil is 81 per cent monounsaturated, hemp-seed oil is 80 per cent polyunsaturated and sesame-seed oil is 39 per cent monounsaturated and 45 per cent polyunsaturated.
Oil from flaxseed (also known as linseed) is an unusually rich source of the omega-3 essential fatty acid alpha-linolenic acid (ALA). It also contains the omega-6 essential fatty acid linoleic acid, so its ratio of beneficial, anti-inflammatory omega-3s compared to the pro-inflammatory omega-6s is around 3:1. In contrast, oil from the seeds of the non-drug strain of cannabis, known as the hemp plant, has an omega-3/omega-6 ratio of 1:3 – the opposite to that found in flaxseed oil, which might be expected to promote inflammation in the body. However, a considerable amount of omega-6 is in the form of gamma-linolenic acid (GLA) – the one omega-6 that actually has an anti-inflammatory action. Other nuts and seeds contain a variable blend of omega-6s and omega-3s.
Nuts are also a rich source of vitamins, minerals, trace elements and antioxidant phytochemicals that give them a high ORAC score (see
Table 16
).
Almonds
contain vitamin E and flavanol antioxidants, which prevent oxidation of LDL-cholesterol so that it is more readily carried back to the liver for processing. This means that eating a handful of almonds per day (about 23 kernels) can lower ‘bad’ LDL-cholesterol by 5 per cent and increase ‘good’ HDL-cholesterol by 6 per cent. And in practical terms, researchers estimate that eating a handful of almonds per day can improve your cholesterol balance enough to reduce your risk of a heart attack or stroke by around 20 per cent.
Brazil nuts
are the richest dietary source of selenium, which plays an important immune role and provides antioxidant protection against cancer. Research involving over 1,110 Finnish males also suggests that selenium helps to protect against stroke. Those with the lowest selenium levels were almost four times more likely to experience a stroke than those with the highest levels. Whether or not it also protects against coronary heart disease remains uncertain, although it is possible that selenium may reduce the risk of non-fatal heart attack.
Nut
ORAC score
*
per 30 g serving
Pecans
5,095
Walnuts
3,846
Hazelnuts
2,739
Pistachios
2,267
Almonds
1,265
Peanuts
   899
Cashews
   567
Macadamias
   481
Brazil nuts
   403
Pine kernels
   204
*
ORAC score = micromol of TE.
Macadamia nuts
and
hazelnuts
are among the richest dietary sources of monounsaturated fats. As well as lowering ‘bad’ LDL-cholesterol levels, monounsaturated fat has an anti-inflammatory action and a beneficial effect on immunity.
Peanuts
are a source of the antioxidant phytochemical resveratrol – also found in red wine – which is believed to protect against atherosclerosis and coronary heart disease. Unfortunately, peanuts are often eaten roasted or salted, which detracts from their nutritional value – eat them fresh and unsalted for maximum health benefits.
Walnuts
are a good source of omega-3 essential oils that have a beneficial effect on cholesterol balance as well as reducing inflammation. They are also a good source of antioxidants such as vitamin E and selenium. Research suggests that regular consumption of walnuts can lower ‘bad’ LDL-cholesterol enough to reduce the risk of coronary heart disease by 30 to 50 per cent and increase lifespan by an estimated five to ten years.
Aim to eat around 30 g of nuts or seeds daily either as a healthy snack, or added to muesli or bread and sprinkled onto salads and other meals. Buy them fresh, little and often, for maximum freshness, from a shop with a rapid turnover.
Milk and dairy products
Milk is an important source of calcium for healthy bones and teeth. Dairy products that retain their calcium content are included in this group, but those that consist mostly of milk fats (cream and butter) are not, as these provide energy in the form of fat with little additional nutritional value. The nutrient content of important members of this group is shown in
Table 17
.
Most people would benefit from obtaining three servings of these products per day, which should ideally be low-fat or fat-free such as skimmed or semi-skimmed milk, low-fat natural from age frais or yogurt, cottage cheese and just small amounts of fat-dense hard cheese (40 g or 1½ oz).
Lactose intolerance
A surprising number of people are intolerant of the milk sugar, lactose, which is naturally present in sheep, cows’ and goats’ milk in similar quantities (around 10 g per glass). Worldwide, lactose intolerance affects 95 per cent of people of Asian origin, over 75 per cent of Afro-Caribbean people and 50 per cent of those from South America. North-Western Europeans and those with European ancestry such as white North Americans, however, are less likely to be affected. Normally, all mammals produce the lactase enzyme needed to break down milk sugar (lactose) whilst being breastfed. After weaning, lactase enzyme secretion reduces then stops in preparation for following an adult diet that, traditionally, has consisted of meat, grains, vegetables and fruit but no dairy products. A few thousand years ago, however, a genetic mutation occurred in the lactase gene so that lactose production persisted. This is thought to have arisen in Europe within a population of dairy farmers. Retaining lactase activity provided a survival advantage as it allowed the continued consumption of nutritionally rich cows’ milk – especially when other foods were scarce. It was passed on as a dominant genetic trait (i.e. only one copy of the gene that allows lactase persistence is needed for someone to continue tolerating milk into adulthood). This mutation – and similar ones arising spontaneously elsewhere – quickly spread among populations in Northern Europe and Scandinavia, and also included some nomadic peoples travelling to the Middle East and Africa.
Food
Carbohydrate (as sugars)
Protein
Fat
Energy
Calcium
Skimmed milk
4 g
3 g
0.2 g
32 kcal
122 mg
Semi-skimmed milk
5 g
3 g
1.7 g
46 kcal
120 mg
Whole milk
4.5 g
3 g
4 g
66 kcal
118 mg
Cheddar cheese
0
25 g
35 g
416 kcal
739 mg
Brie soft cheese
0
20 g
29 g
343 kcal
256 mg
Cottage cheese (low-fat)
3 g
13 g
1.5 g
79 kcal
485 mg
Lactose is a disaccharide made up of two sugars, galactose and glucose, joined together. Lactose is digested by an enzyme, lactase, secreted by cells within the lining of the small intestines. This separates the galactose and glucose, which are then absorbed. When insufficient amounts of lactase are produced, however, lactose stays within the gut to reach the large intestines, where it is fermented by bowel bacteria. This can produce symptoms of nausea, bloating, audible bowel sounds (borborygmi), wind, cramping abdominal pains and diarrhoea.
People who suspect they are lactose intolerant may find that cutting lactose from their diet and using milk alternatives can alleviate the symptoms. Low-lactose cows’ milk is available, containing less than 1 g lactose per glass, while milks made from soy, rice and nuts are lactose-free. Yogurt made from cows’ milk also has a low lactose content, as bacterial fermentation breaks the lactose down. Alternatively, lactase drops can be added to any drink to replenish the missing enzyme.
If you are avoiding milk products because of lactose intolerance, you will need to ensure an adequate intake of calcium from alternative sources such as calcium-enriched soy milk, eggs, green leafy vegetables, whitebait, tinned salmon and sardines (which include soft bones), pulses, nuts and seeds.
Fish
As shown in
Table 18
, fish are an excellent source of protein. Oily fish such as herring, salmon, mackerel and pilchards are also a rich source of long-chain, omega-3 polyunsaturated fatty acids and vitamin D. The flesh of white fish, such as cod and tinned tuna (which has been processed) contain very little omega-3 oil, however.
Food
Protein per 100 g
Fat per 100 g
Total
long-chain omega-3 per 100 g
Vitamin D per 100 g
Energy per 100 g
Herring
18 g
13 g
1.3 g
19 mcg
190 kcal
Salmon, fresh
18 g
12 g
2.2 g
16 mcg
182 kcal
Salmon, canned in brine (drained)
24 g
7 g
1.6 g
9 mcg
153 kcal
Mackerel
19 g
16 g
1.9 g
8 mcg
220 kcal
Kippers
18 g
18 g
2.6 g
8 mcg
229 kcal
Pilchards (canned in tomato sauce)
17 g
8 g
2.6 g
14 mcg
144 kcal
Tuna, fresh
23 g
5 g
1.3 g
1 mcg
144 kcal
Tuna (canned in oil, drained)
27 g
9g
0.4 g
3 mcg
189 kcal
Cod
18 g
<1 g
0.3 g
trace
80 kcal
Haddock
19 g
<1 g
0.2 g
trace
81 kcal
Plaice
17 g
<1 g
0.3 g
trace
79 kcal

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