Nutrition (23 page)
Most dietary salt (around 75 per cent) is hidden in processed foods including canned products, ready-prepared meals, biscuits, cakes and breakfast cereals. Some foods are 30 per cent more salty than seawater, which provides 2.5 g salt per 100 g water. Checking labels of bought products and avoiding those containing high amounts of salt is vital to influence your salt intake. A good general rule is that, per 100 g food (or per serving if a serving is less than 100 g):
• 0.5 g sodium (1.25 g salt) or more is a lot of sodium
• 0.1 g sodium (0.25 g salt) or less is a little sodium
To convert ‘sodium’ to salt content, simply multiply by 2.5, so that, for example, a serving of soup containing 0.4 g sodium actually provides 1 g salt (sodium chloride).
Salt is easily replaceable with herbs and spices such as black pepper. When cutting back on salt, it takes around a month to retrain your taste buds, and food may taste bland initially until your taste buds start responding to lower salt concentrations. Try adding lime juice to food, which stimulates tastes buds and decreases the amount of salt you need, too.
The importance of potassium
Where salt is essential, use mineral-rich rock salt rather than table salt, or use a low-sodium, higher-potassium brand of salt sparingly. Potassium helps to flush excess sodium from the body via the kidneys, and a diet that is lacking in potassium is linked with a higher risk of high blood pressure and stroke, especially if your diet is also high in sodium. In one study, people taking medication for high blood pressure were able to reduce their drug dose by half – under medical supervision – after increasing the potassium content of their food. Good sources of potassium include seafood, fresh fruit, vegetables, juices and wholegrains.
To cut back on salt intake avoid:
• adding salt during cooking or at the table
• obviously salty foods such as crisps, bacon, salted nuts
• tinned products, especially those canned in brine
• cured, smoked or pickled fish and meats
• meat pastes, pâtés
• ready-prepared meals
• packet soups and sauces
• stock cubes and yeast extracts
• check all labels and select brands with the lowest salt content
Other food additives
As well as adding salt to processed foods, manufacturers also add a variety of different chemicals to enhance colour and flavour and to preserve products for a longer shelf life. These additives are displayed on labels with identification codes based on an international numbering system. In the European Union, the numbers are prefixed with the letter E, but in the US the number alone is used. Some additives are natural, but many are artificial and would not otherwise feature in the diet. The number classifications are available on the internet:
Europe
United States
Australia
Food additives are generally recognized as safe. However, they have been linked with health problems in some people. Research looking at the effects of artificial food additives in the diet of almost 2,000 young children, for example, found that eliminating artificial colourings and benzoate preservatives produced significant improvements in behaviour, with less hyperactivity.
Monosodium glutamate (MSG) is an amino-acid flavour enhancer used in Asian cuisine. It stimulates specific taste-bud receptors to induce a savoury or meaty taste known in Japan as
umami.
Consuming MSG increases blood levels of the amino acid, glutamate. This acts as a building block for making the neurotransmitter acetylcholine which, in some people, can cause headache and may trigger asthma in those sensitive to its effects. Studies are inconclusive, however, and it has been suggested that this sensitivity may only occur in those with a deficiency of vitamin B6, or after consuming MSG on an empty stomach, or with alcohol, which hastens its absorption.
umami.
Consuming MSG increases blood levels of the amino acid, glutamate. This acts as a building block for making the neurotransmitter acetylcholine which, in some people, can cause headache and may trigger asthma in those sensitive to its effects. Studies are inconclusive, however, and it has been suggested that this sensitivity may only occur in those with a deficiency of vitamin B6, or after consuming MSG on an empty stomach, or with alcohol, which hastens its absorption.
MONOSODIUM GLUTAMATE
MSG may appear on food labels as monosodium glutamate, sodium glutamate, 2-aminoglutaric acid or as additive number E621. It is also present in flavourings described as: hydrolyzed vegetable protein (HVP), hydrolyzed plant protein (HPP) and ‘Natural Flavour’. People who are highly sensitive to MSG may also react to other glutamic acid salts. The names and E numbers to look for are:
E620 glutamic acid
E621 monosodium glutamate
E622 monopotassium glutamate
E624 monoammonium glutamate
E625 magnesium diglutamate
Some people with asthma are sensitive to benzoates, especially if they are also sensitive to aspirin. Benzoates are among the most commonly used food additives. These preservatives are used to prevent the growth of bacteria, yeasts and fungi in many foods and drinks, especially those that are acidic. Benzoyl peroxide is also used as a bleaching agent in flours, breads and some cheeses such as soft Italian cheeses, blue cheeses (especially Gorgonzola) and feta cheese. The way in which benzoates can trigger asthma is unknown, but may involve the production of inflammatory chemicals.
BENZOATES
These may appear on labels as any of the following:
E210 benzoic acid
E211 sodium benzoate
E212 potassium benzoate
E213 calcium benzoate
E214 ethyl paraben (ethyl para-hydroxybenzoate)
E215 sodium ethyl para-hydroxybenzoate
E216 propylparaben (propyl para-hydroxybenzoate)
E217 sodium propyl para-hydroxybenzoate
E218 methyl paraben (methyl para-hydroxybenzoate)
E219 sodium methyl para-hydroxybenzoate
In addition, as many as one in ten people with asthma are sensitive to sulphites, especially those whose asthma requires steroid treatments or who are sensitive to aspirin. Sulphites (or sulfites) are antioxidant preservatives used to preserve colour, slow the browning of fruit, vegetables and seafood, and to bleach food starches and bread dough. At one time, they were widely added to fresh fruit and vegetables, especially lettuce. As a result of an increase in sensitivity reactions, however, their use was restricted during the mid-1980s and they are now only used where no suitable alternative exists.
When sulphites dissolve in the mouth during chewing, sulphuric acid is formed, which releases sulphur dioxide gas. When inhaled, this noxious gas irritates hypersensitive airways to cause spasm. Sulphites also interact with proteins on cell membranes, and may alter them sufficiently to be seen as ‘foreign’ and trigger an allergic reaction. Another theory is that some people with asthma only produce low levels of an enzyme (sulphite oxidase) which is needed to convert sulphites to inert sulphates.
SULPHITING AGENTS
Sulphiting agents that are used in the food and drinks industry may be shown on labels as follows:
E220 sulphur dioxide
E221 sodium sulphite
E222 sodium bisulphite (sodium hydrogen sulphite)
E223 sodium metabisulphite
E224 potassium metabisulphite
E225 potassium sulphite
E226 calcium sulphite
E227 calcium hydrogen sulphite
E228 potassium hydrogen sulphite
Sulphur and sulphites may be spelled as sulfur or sulfites on labels.
NB Sulphates (sulfates) are
not
associated with sensitivity reactions.
not
associated with sensitivity reactions.
Organic foods
According to the Soil Association, the UK’s leading charity campaigning for healthy, sustainable food, record numbers of people are now choosing to eat a wholesome, natural, organic diet because they feel that by doing this they are making a healthier choice.
What does ‘organic’ mean?
Organic foods are produced using sustainable farming practices without the use of agricultural chemicals (pesticides, weedkillers, fungicides, fumigants, antibiotics, hormonal growth promoters, artificial fertilizers), genetic manipulation, irradiation or undue exposure to environmental pollution. In their place, farmers use traditional methods of pest control, crop rotation, rotation with green-manure crops such as clover (which fix nitrogen in the soil and thereby act as natural fertilizers), careful timing of sowing and allowing land to lie fallow. This results in products that are full of flavour, in comparison to their non-organic counterparts, vitamins and minerals and which contain the lowest possible amounts of artificial chemicals.
In contrast, non-organically grown produce is regularly treated from the time the crop is in seed form, during germination and throughout its growing cycle. A non-organic apple, for example, is typically dosed around 40 times with up to 100 additives before you eat it. These chemicals do not just lie on the surface of the produce, but are found beneath the skin and sometimes throughout the flesh itself. A typical non-organic lettuce is sprayed with artificial fertilizers and pesticides an average of 11 times in the few weeks it takes to develop, while a Cox’s apple is sprayed 16 times with 36 different active pesticide ingredients before you pick it up and eat it. And apples on the outside of the tree can receive 13 times the amount of spray present on those near the inside of the tree. These treatments are designed to boost growth and prevent attack from moulds and insects. In contrast, organic crops are either not sprayed at all, or are treated with a tightly regulated list of organic products such as pyrethrum (a Chrysanthemum extract), neem oil (from neem-tree seeds) or beneficial soil bacteria (e.g.
Bacillus thuringiensis
) that kill weevils without harming humans.
Bacillus thuringiensis
) that kill weevils without harming humans.
The full effects of many chemicals on long-term health are still not fully understood. Some researchers suggest that 60 per cent of all herbicides, 90 per cent of all fungicides and 30 per cent of all insecticides can potentially cause cancer, but the mutagenicity of most pesticides is unknown because it has not been studied. Consuming more than one toxin at the same time may magnify their toxic effects.
Limits on the level of pesticide and herbicide residues in food are set for health reasons, but these assume that chemicals are properly used. If improperly used, serious harm may result. You might assume that improper use is rare, but unfortunately this is not the case. Testing of non-organic fruit and vegetables on sale in the UK has found that nearly half (48 per cent) contained detectable pesticide residues, as did over a quarter (28.6 per cent) of other foods tested, including cereals, meat, dairy, fish and processed foods. Many samples of lettuce, apples, oranges and pears contained residues of between three and seven different pesticides. Although each individual chemical was present at safe levels, American researchers have found that combining pesticides at safe levels can multiply their toxicity and may have effects on reproductive-, immune- and nervous-system function. Concern was sufficient for the UK government to recommend washing and peeling fruit before eating ‘as a sensible precaution’ – especially when preparing them for children – and that topping and tailing carrots was also a good idea to reduce exposure to residues, although the advice was subsequently withdrawn as many nutrients are stored just beneath the skin, and peeling will not remove residues that have a ‘systemic’ effect, which means that they are designed to be taken up into the plant and therefore found not just on the surface, but throughout their entire flesh. Unfortunately, washing with water alone does not remove residues altogether as those used have been formulated to resist being washed off by rain. According to the Soil Association, after washing with water between 50 and 93 per cent of residues remain on potatoes, apples and broccoli. Blanching in hot water and cooking can remove significant amounts of some pesticide residues, however.
Although the adverse health effects of agricultural residues in the diet are not known, a number of researchers have linked them with symptoms such as headache, tremor, lack of energy, muscle weakness, depression, anxiety, poor memory, nausea and diarrhoea, plus reduced male fertility, suppressed immunity and cancer. Much of this evidence comes from environmental and occupational exposure studies in agricultural workers. Whether dietary exposure from residues on foods can cause similar effects is less easy to confirm as data is incomplete.
HOW MUCH IS TOO MUCH?
It’s estimated that, during the course of one year, those following a non-organic diet consume around 6 kg of chemicals such as food additives, colourings, flavourings, preservatives, waxes, fertilizers, pesticides and herbicide residues.
Nutritional quality of organic versus non-organic foods
Evidence from over 400 published papers suggests that there are notable nutritional differences between organic and non-organic foods. Although some academics argue that these are confounded by differences in water content (organic produce tends to contain less water and is therefore more nutrient-dense) this still means that, per serving, you are obtaining less water and more nutrients. In addition, at least 22 studies have compared the vitamin and mineral content of organic and non-organic fruit and vegetables using dry matter only, and eight have similarly compared the vitamin, mineral and protein content of cereals. Having taken water out of the equation, these consistently suggest that organic produce contains more minerals (especially phosphorus, potassium, calcium, magnesium, zinc) and more vitamin C. In one study, organic cherry tomatoes, for example, contained 4.5 per cent more potassium, 129 per cent more calcium and 65 per cent more zinc than in those grown traditionally, although the manganese content was 11 per cent lower.
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