To the Vitamins and Minerals in an Overflowing Cornucopia of "Weeds"
1. It is time to revisit our long-running (starting even before the launch in 1976 of our Green Planning for research) surveys, "turning the spotlight on the halogens", on the nutritional and environmental significance of the elements fluorine, chlorine, bromine, and iodine and the associated ionic forms (halides) in particular; iodide (and, in another speciation, iodate) comes to the fore in our considerations of agriculture, fishing, water, food, beverages, and recycling. Some significant advances in our knowledge (and generation of new queries to add to some of the outstanding questions are still not fully answered).
2. Overhauling the nutritional information and comment that we can present in our Portfolio of Eating Plans, which has been running for 4 years or so, we can now adduce data to fill some of the empty boxes left to remind and challenge us with omissions. The British Composition of Food Tables, like their American equivalents, are now on open access on the Food Standards Agency's (FSA) website, possibly in response to some constant requests to the Agency by us. Some of the data now generally available include results obtained from analyses and measurements obtained or made by VEGA and we can supplement them with more information obtained by retailers of seaweed products that have not been published or used before. They will be added to the compilation in "McCance and Widdowson" on the FSA website and used in tabular form in this presentation, which will need copious notes for their interpretation.
Chemistry and Data
3. Our survey of the nutritional significance of plant-based dietary patterns, comprising terrestrial and marine sources, is nicely complemented by a recently-published supplement to the American Journal of Nutrition (Am J Clin Nutr 2009; 89(suppl), 5(S)). We shall concentrate here on iodide (and iodate), dietary factors (in which the element selenium is implicated), interactions with other potential nutrients and anti-nutrients, and methods of analysis and the consequences of supplementation (eg in polypills) and screening for signs of deficiency or excess (and consequences in specifying recommended dietary amounts or intakes (RDAs or RNIs) and ranges that vary according to gender and age (they rise, for instance, during pregnancy and have effects on the baby's brain - which may not extend to frank goitre - and the duration of the gestation. Further, symptoms of hypothyroidism or hyperthyroidism may have origins in genetics and autoimmunity. Means of diagnosis are being improved, and uninformed resort to over-the-counter supplementation is imprudent; and fortification of foods requires judgment and assessment against adventitiously boosted intakes swing to gaps in information in the Composition of Food tables.
4. The latest Declaration from the International Council for Control of Iodine Deficiency Disorders (ICCIDD) on the Importance and Safety of optimizing Iodine Nutrition records the continued prevalence worldwide of iodine deficiency, leading to goitre and thyroid dysfunction as the main preventable cause of mental retardation globally. "Optimizing iodine intake is widely recognized as the most cost-effective solution for achieving optimal intellectual development in addition to normalized thyroid function in iodine deficiency areas.
Too Much or Too Little
5. "The issue of the safety of increasing iodine intake has recently been raised based on occasional regional reports of detrimental side effects due to excessive amounts of iodine. The current WHO recommended daily intake of iodine for adults is between 150mcg and 300mcg per day. The European Commission and the US Institute of Medicine have discussed tolerable upper iodine intake for adults and have indicated amounts of 600mcg and 1100mcg per day, respectively".
6. The Declaration continues: "Mild thyroid hyperfunction may occur following an increase of iodine intake within the recommended range as a consequence of pre-existing autonomous nodular goitre due to longstanding iodine deficiency. This is a transient effect. The single relevant adverse effect is iodine-induced overt hyperthyroidism, only induced in severely iodine-deficient populations after a rapid introduction of excessive iodine supplementation, which should and can be avoided. Excessive iodine intake may lead to a transient small increase in the prevalence and incidence of subclinical hypothyroidism and thyroid autoimmunity, especially in older individuals".
7. These warnings are followed by further comment, "Insufficient monitoring of salt iodine content and iodine intakes in populations increases the risk of induced hyperthyroidism and other side-effects. With sustained quality assurance and monitoring these can be almost entirely avoided. While the overall incidence of thyroid cancer in populations does not appear to be influenced by iodine intake, a shift to less malignant types of thyroid cancer is widely recognized as a consequence of introducing iodine prophylaxis". The Declaration concludes that "optimal intake supported by adequate monitoring has been widely shown to improve the quality of various health aspects. The benefits of iodine supplementation far outweigh the relatively small risks of iodine excess".
Thailand as an Example
8. Pregnant Thai women are reckoned to be iodine deficient, with "mild-to-moderate" urinary iodine (UI) levels of 108 (11 to 558) mcg/l. Their school-aged children (who would normally be regarded as markers for the whole human population) yielded comparable results of 200 (25 to 835 mcg/l), indicating optimal iodine status. Estimated iodine intakes in the 2 groups lay in the range 130 to 170mcg/l. These results were obtained in metropolitan Bangkok, where a higher frequency of seafood meals was a significant predictor of UI in both groups, but household use of iodized salt was not. Varying dietary habits upset the correlations, but suggest that adequate monitoring of IDD in populations should include specific monitoring of pregnant women, for whom recommended intakes during pregnancy are 250mcg/d but 150mcg/d for non-pregnant women. Studies of mothers-and-children pairs in families would make a valuable example of health programs in developing economies and the importance of the diet and manipulations (fortification - or "mass medication"- in this case) of staples, of questionable desirability, such as common salt, which are causing the Food Standards Agency many concerns in their profiling schemes and efforts at curtailing intakes of dietary sodium; likewise, bread is coming into the spotlight as a carrier of other means of mass medication.
9. There are a number of goitrogens, which are antinutritional factors, to consider as antagonists in the action of dietary iodide that are particularly significant in medical and veterinary contexts in populations of humans subsisting on poor and unstable diets and on other animals depending on exiguous opportunities from grazing or inadequacies in feeds for livestock kept intensively on "exotic" bought-in products, as well as for companion animals, especially dogs, inadequately fed. Goitre caused by iodine deficiency is common in newborn pigs, lambs, calves, and foals in iodine-deficient areas. Offspring of iodine-deficient dams may fail to survive for long.
10. Certain plants may produce goitre when ingested in sufficient amounts, especially in the absence of adequate intakes of iodine. Lack of hair (especially in pigs) or wool (in lambs) can be added to the usual symptoms of goitre. In non-human animals intakes of low levels of cyanogenic glycosides, eg in white clover, the glucosinolates of brassica species, and in mimosine in Leucaena leucocephala would concern farmers (especially organics) and vets; for human consumers the list could be extended, with special relevance to soya beans, cabbage, rape, kale, and turnips. Cooking and heating and the usual processing of soya bean meal convert the anti-nutrients into substances that are at least non-goitrogenic (some are possibly volatile and noticeable). Here again, we have to reinforce our pleas to the FSA for increased interest and help on scientific aspects.
Biology and Geology
11. There are further complications in what may seem at the first sight a simple connexion of the effective functioning of the thyroid gland and intakes of "iodine". Inclusion of all results in composition of food tables and now collated by us leaves many questions unanswered, for which studies of geology (especially on water supplies), climate, botany, and biochemistry and chemical analysis) have to be assessed. The appropriate plants seem to be confined to sea water vegetables and micro-algae, which filter out and concentrate salts such as chlorides and iodides. The botanical and seasonal significances of these factors are not fully understood. With help from the watercress industry we failed to find any uptake of inorganic iodide added to the fresh water in which the crop is usually grown; further, we found insignificant amounts of iodine in shore-line plants such as samphire.
12. Drinking water itself may contain inorganic iodide, which may also attract more attention for its content of fluoride, "natural" or added. Fluoride is another halide, possibly competitive and exerting a goitrogenic effect. In advising the public we have to consider the significance to advocates of organic and raw food regimens, which could extend to queries over the speciation of the element in sea-plants: it could be accumulated as a water-soluble inorganic (to a chemist) as iodide (or iodate) or as a fat-soluble organic (but possibly volatile) component, or it could contain both forms. In usual methods of analysis the element would be recorded as iodide, because they are destructive; they may therefore lose volative materials, for which there is some evidence from natural decay on shore and the development of the seaside smell of "ozone", which could comprise organic iodides of low molecular weight but high volatility, toxicity, and inclusion with sulphurous compounds as greenhouse gases.
Ecology and Environment
13. The environmentalist must take into account other factors common to fish caught for food, some from industrial pollution such as PCBs, dioxins, heavy metals (such as mercury, cadmium and lead, as well as arsenic) which may be in a harmless ("chelated") speciation. Just as in fishing, especially of the inshore types, intensive cultivation and harvesting of seaweed crops may scour the maritime eco-systems harmfully. There are already qualms in this regard over sea-weed cultivations in Brittany, where production is associated with harvests of shellfish. Concentrated minerals resulting from calcination of plant-materials may yield dry matter from kelp, used for supplements (possibly formulated with essential mineral nutrients such as calcium and magnesium). In Europe such products are under survey for their purity.
14. The seaweed industry is becoming profitable as a source of ingredients and agents extensively utilized by the food industry for purposes of gelling and thickening. They adjust textures with the versatility of animal-derived gelatines and are therefore of particular interest to vegetarians. Erythrosine, a synthetic coloring matter, used for "strawberry" and "raspberry" products, is also rich in iodine. We have passed on to the publishers of McCance and Widdowson the results we obtained from the then Laboratory of the Government Chemist for carrageen, agar, and alginate; however, we cannot declare how much of the iodine that these compounds contain is absorbed by consumers. Some drugs, likewise, have a high content of iodine; amiodarone is among these and doctors prescribing it would have precautions they should observe in maintaining a good level of iodine status in their patients. Iodide content in some relevant foods is not declared. It should be.
15. Stocks of potassium iodide (or iodate) are held for general administration if a nuclear accident contaminated the environment with a radioactive form of iodine that would concentrate harmfully in the thyroid gland; it is a property of iodide to "home in" on the thyroid gland, where it could in excess cause severe clinical problems and cancer. Use of intakes of normal iodide flushes out radioactive form and reduces the danger. However, this precaution may take longer than expected to act effectively. Sheep in Britain's northern less favored areas are still being born and reared unfit to eat, notwithstanding periods of agistment in uncontaminated lowland areas all these years after the Chernobyl accident.
16. A diet suitable in preparation of a patient with thyroid cancer for careful treatment with radioactive iodide requires "draining" the gland with an iodine-deficient diet, so that the radioactivity is suitably concentrated. This may take 3 weeks in hospital, but the same depleting effect may be achieved by adoption at home of a vegan dietary. We try to alert vegans and others reviewing their eating plans and why we give users of our Portfolio of Eating Plans all the relevant information we can, and we continually overhaul them with inclusions, adaptations, and specially designed recipes and menus, with which they can consult doctors or registered nutritionists or dietitions for advice before they resort to any "OTC" (over the counter) supplements (which should be assessed with the same expert attention as polypills, multivitamins etc).
17. GPs should pick up signs of thyroid inadequacy in a consultation. Symptoms of depression, changes of weight and appearance may attract further investigation. 24-hour urine samples are not practicable on patients with a variety of eating patterns, but doctors and nurses and vets may have recourse to non-invasive ultrasound measurements (ultrasonography) supported by analysis of blood-samples for thyroid-stimulating hormone (TSH, thyrotropin) in the first instance. An endocrinologist might require further tests for biomarkers of iodine status such as thyroglobulin (Tg), another protein, and serum thyroxine (T4). Tests involving triiodothyronine (T3) are generally not reliable.
Species, Harvesting, and Blooms
18. Research topics for sea plants ("weeds") and mariculture and collection of wild crops are attracting increasing investment and development, with China leading, followed by France, then Japan and Chile. The industries are included for many purposes under the headings appropriate to commercial fishing. The British Isles offer coastlines with apparently good possibilities, which could include replacement of moribund industries (eg crop failures through diseases in shellfish) and waste through overfishing and losses due to by-catches. Remediation of contaminated waters could also be exploited. In Europe trade in seaweed is a very old tradition along the north coast of Finiste?e in Brittany. The seaweed is either collected from the beach or from boats equipped with motorized mowers that chop up the seaweed. The Breton coast line is host to about 800 different species of seaweed, which are divided into 3 major groups: green, brown, and red algae. The red and brown algae are of most interest commercially, whereas the green algae can cause "green tides" that overwhelm the other varieties. Red algae are collected to extract carrageenan and agar. All species of brown algae contain the polysaccharide alginate. In traditional systems the catches are seasonal.
Alternative to Fish
19. In the Far East seaweed is used predominately for food and medicine; in the West it is used mainly for animal feed and fertilizer. For a long time seaweed has been used industrially to produce soda and iodine. Consumers are taking more interest in the nutritional value of seaweed and in the use of algae in cosmetics and medicines. Renewed interest in use for "natural" fertilizers has arisen. Brittany is a promising point for seaweed production: the northern cool waters and southern hot waters meet off the coast of Finiste?e, which is popular for holiday makers and amateur sailors, as well as romantic for its traffic in spies and special agents during WW2. Commercial seaweed interests have been vaunting "the excellent nutritional content" of the algae: "mainly high levels of protein, carbohydrates, vitamins A, B, and C, as well as many trace elements and minerals, the most prominent of which is iodine. Another plus is that they are low in calories and suitable for the growing vegetarian market."
20. Seaweed farming has to compete with offshore fish farming in the uncertain conditions of commercial mariculture. Disappearance from Brittany coasts of major populations of "Atlantic kelp" Laminaria digitata has become another setback, this being the main commercial species of the region, which is used to produce alginates. Kelp fields in the south of Brittany have entirely disappeared. Climate change has been blamed; however, significant populations of this species growing in the cooler waters of Normandy have also disappeared. These losses are blamed on pollution, which causes competition with a species of green algae which produces spectacular algal "blooms" (the green tides), which are believed to be due to increased nitrate pollution and agricultural runoffs. Harvests are being dominated by the opportunistic kelp species Sacchorhiza polyschides, which goes faster than Laminoria, but has a very low alginate content. Kelp collection may be leading to habitat degradation, with the correlations of overgrowths. There are many reasons that could be advanced for the decline of algal populations, among which over-collection may be one. There are also supply issues with edible seaweeds such as red algae eg dulse (Palmaria palmate), which faces competition from the green algae, which thrive under eutrophic conditions. Algal cultivations for feeds and foods are being grown to enhance their value of as sources of "omega 3s".
21. Local plants, not seaweeds, being commercialized in Brittany include rock samphire (Crithmum maritimum, a member of the carrot family), a salt-loving plant which in Brittany grows on rocks along the shore.
22. Introduction of iodized salt to bread, which is due to be implemented in New Zealand in September 2009 to improve the iodine status of NZ children, has been proved to achieve its aim of improving their iodine status but with the growing disquiet of reliance on iodized salt and use of bread as vehicles of "mass-medication" (Rose M et al, NZ Med J. 2009; 122(1290): 14-23. "Biofortification" by treatments of soils and crops with as many as 7 mineral elements often lacking in human diets (iron, zinc, copper, calcium, magnesium, selenium, and iodine) opens up possibilities with untapped potential and less challenge in terms of mass medication (GC van den Berg, Beneficial Nutrients News 4; 3: August 2008).
23. In our campaign for Real Bread (CAMREB), launched in 1976 as an offshoot of our Green Planning for various projects in biofortification of terrestrial crops and means of achieving this objective to overcome deficiencies in British soils in the element selenium, which was reducing the potential of home-grown cereals for purposes such as bread-making, for which North American crops were then superior had to be considered. This lack, which had similar effects in challenges being met in Finland in the Karelia project, has been partly overcome by research and development on farming and food production in northern Europe, notably in plant breeding, fermentation technology, and enhancement of soils with nutrients, such as the element selenium. The Finns applied inorganic sources of this element to their croplands and noted improvements in the uptake of the element and translation through the flour and bread of improvements in keeping with their aims of adjusting the animal:plant content in food and beverage intakes and their campaigns to reduce blood pressure and "syndrome X". Similar soil treatments have been applied in the UK (but probably not by farmers growing for the organic food and feed markets) and the treatments may be of increased significance in the combination of iodine and selenium in the workings of healthy thyroid glands in animals, including humans. Added effects in the dairy industry, by means of cows' diets in particular, produced a beneficial dose response in human consumers (Schöne F et al, J Trace Elem Med Biol. 2009; 23(2): 84-92.
24. Could iodine biofortification prove to offer an unobjectionable alternative to iodized salt in ensuring the worthiness of food and feed in British diets? The answer is probably, yes, providing a solution to iodine deficiency and its control. Contrary to our limited experience with watercress growing in fortified waters, evidence recently produced - although mainly in patents - indicates that "iodine stimulates crop growth." Small amounts of this nutrient improve the assimilation of nitrogen from fertilizers. In this way iodine nutrition increases crop yields and experts in Finland conclude from experiments with oilseed rape (OSR), ryegrass, and wheat that this assertion can be validated. If nitrogen stays for a shorter time in the soil, the nutrient is less prone to leaching, volatilization, or denitrification. Addition of iodine is "especially beneficial to fertilizers high in nitrogen" asserts a Finnish expert, after field experiments with arable crops and grass tested with granular fertilizer compositions containing 50ppm iodine. Moreover, these compositions contained traces of selenium. The experiments and results with OSR, ryegrass and wheat indicate that "iodine and selenium enhance crop growth in a synergistic way."
25. Iodine may also stimulate the plant's antioxidant defence system. A Spanish investigator applied this knowledge in tests in what would seem to be an apt situation: the increase in treated plants, such as lettuce, in antioxidant compounds after the application of iodine in recycling hydroponic systems. Significant accumulation of iodine compounds did reduce the biomass of the treated plants. Up til now, iodine has not been recognized as an essential nutrient. A possible beneficial status of the element "is controversial to many plant nutrition specialists," and experiments show "stimulating effects of iodine as plant nutrients "while many others demonstrate harmful effects, "illustrated by the herbicidal and defoliant properties of iodide. Iodine too is used as a biocide" and it is "effective in the control of a bacterial disease."
26. Many experiments from Zhejiang University in China support claims for the biofortification of arable and vegetable crops, particularly with reference to applications in remote areas and with topics "ranging from iodine-enriched amaranth to iodine-fortified vigna." Spinach is rated "particularly suited for iodine fortification." Forage yields of alfalfa also rate a mention from advocates of biofortification. (Vigna is a type of tropical / subtropical legume, comparable to Phaseolus beans in temperate zones).
27. In asserting a place for mariculture and potential in the plant side of the bounty the food chain of components in the 5-fruit-and-veg importance and means of reducing and replacing our consumption, for many healthy reasons, of "meat-and-dairy" (a definition that alludes to fish and the industrial corollaries), we see the need for overhauling by, say, the Food Standards Agency, the knowledge and corollaries we have been dealing with over many years, with access to various scientific disciplines and to epidemiologists, market and labelling monitors, nutritionists, environmentalists, and health professionals. Misunderstandings over iodization of salt and the possible need for screening of, at least, special groups on restricted diets, and simple diagnostic tests require attention. From the environmentalists' point of view intensified cultivation of sea plants must avoid the depredations, waste, and dangers that have overcome the "animal" side of mariculture and take account of opportunities already being exploited, of "fields" of impounded waters such as might be included in schemes for energy-production like the Severn Barrage.
28. Doctors should brush up their knowledge of the thyroid gland and its biochemistry. Surgeons must be reminded of the importance of the associated apparatus of the parathyroid glands and the cells producing calcitonin, careless removal of which may be followed after operations on the thyroid gland by disturbances in bone metabolism and upset calcium blood levels. After surgery of the thyroid gland patients may have to depend on synthetic L-Thyroxine. In N America particularly some doctors prescribe old-fashioned extracts of animal (usually pig) thyroid glands, which will probably need extra adjustment according to the iodide status of the donor animals. Assessment of patients should also ensure that they show no signs of impaired biosythesis of L-tyrosine, the precursor of L-thyroxine. Clues to this deficiency would appear to doctors and vets looking for signs of other biochemical and hormonal problems.
29. Debate on fluoridation of water supplies, from the tap or bottled waters and beverages, must not overshadow and confine consideration of the iodide content, once regarded, in the UK, at least, as negligible (we also had analyses done of common salt - sodium chloride - and specimens of "sea-salt", found to have similarly low levels of iodide). However, some later results reveal arresting differences within Denmark, a small land area, but with a relatively long coastline: a WHO global average for drinking waters puts an iodide content at 4mcg/litre, but within Denmark supplies may vary between 2mcg/litre and 140mcg/litre (the later due to "humic substances") . In Denmark therefore consumption of tap water alone could satisfy the recommended daily intake of iodide, even for a pregnant or lactating woman. Such variations cannot be accommodated in our Portfolio of Eating Plans, examples of which are presented, in which convenient sources of seaweed are used, some with comparisons with fish meals, with special regard to iodine content, and with other nutrients and factors, such as sodium and the corollaries in the FSA's Profiling system. We also suggest that the BMA's booklet, available in many pharmacies, on Thyroid Problems, is brought up to date with material that the FSA should be able to offer to the public on the place of seaweeds among the esteemed 5-fruit-and-veg.