Definition: In this task, you are given a text of many news articles seperated by special token "|||||". Your task is to summarize them.
Input: LONDON Researchers cast doubt on the prevailing wisdom that vitamin D supplements can prevent conditions like cancer, diabetes and heart disease, saying on Friday low vitamin D may be a consequence, not a cause, of ill health. 
  
 The findings could have implications for millions of people who take vitamin D pills and other supplements to ward off illness - Americans spend an estimated $600 million a year on them alone. 
  
 Vitamin D, sometimes known as the "sunshine vitamin" is made in the body when the skin is exposed to sunlight and in found in foods like fish liver oil, eggs and fatty fish such as salmon, herring and mackerel. 
  
 It is known to boost the uptake of calcium and bone formation, and some observational studies have also suggested a link between low levels of vitamin D and greater risks of many acute and chronic diseases. 
  
 But it is not clear whether this is a cause-and-effect relationship, so various large trials have been conducted to try to test whether vitamin D supplementation can reduce the risk of developing disease. 
  
 Researchers led by Philippe Autier of France's International Prevention Research Institute in Lyon analyzed data from several hundred observational studies and clinical trials examining the effects of vitamin D levels on so-called non-bone health - including links to illness such as cancer, diabetes and cardiovascular disease. 
  
 They found that the benefits of high vitamin D levels seen in observational studies — including reduced risk of cardiovascular events, diabetes and colorectal cancer - were not replicated in randomized trials where participants were given vitamin D to see if it would protect against illness. 
  
 "What this discrepancy suggests is that decreases in vitamin D levels are a marker of deteriorating health," said Autier. 
  
 In other words, he explained, serious illness like cancer and diabetes may reduce vitamin D concentrations, but that does not necessarily mean that raising vitamin D levels would prevent the illness from occurring. 
  
 Yet experts not involved in Autier's review said its conclusions were not definitive, and cautioned against reading it as a reason to dissuade people from taking vitamin D. 
  
 "This paper is very useful because it highlights the need for more long term intervention studies specifically looking at the effect of proper vitamin D supplementation on disease risk," said Nigel Belshaw, research leader at Britain's Institute of Food Research. 
  
 "However, it does not suggest that taking vitamin D supplements cannot be useful in some cases for some purposes. Neither does it rule out a health advantage of increasing vitamin D levels in the blood for those who are deficient." 
  
 Helen Macdonald, a professor of nutrition and musculoskeletal health at Britain's University of Aberdeen stressed that vitamin D was important for bone health. 
  
 "And we already know that people who are at risk of vitamin D deficiency, like older people, pregnant and breastfeeding women, young children and people with darker skin, need to take a supplement because it is difficult to boost vitamin D levels from food sources alone," she said. 
  
 She added that Autier's study did, however, appear to confirm what many nutrition experts have suspected for a while - "that healthy people probably don't need to take a high dose supplement and that the best source of vitamin D for most people is sunlight in the summer, always taking care not to burn." 
  
 (Reporting by Kate Kelland, editing by Andrew Heavens) ||||| Image caption Vitamin D supplements are recommended for young children and the elderly 
  
 Scientists have cast doubt on the value of vitamin D supplements to protect against diseases such as cancers, diabetes and dementia. 
  
 Writing in The Lancet Diabetes and Endocrinology, French researchers suggest low vitamin D levels do not cause ill health, although they did not look at bone diseases. 
  
 More clinical trials on non-skeletal diseases are needed, they say. 
  
 Vitamin D supplements are recommended for certain groups. 
  
 What this suggests is that decreases in vitamin D levels are a marker of deteriorating health. Prof Philippe Autier, International Prevention Research Institute 
  
 Recent evidence has shown it may also have a role to play in preventing non-bone-related diseases such as Parkinson's, dementia, cancers and inflammatory diseases. 
  
 Prof Philippe Autier, from the International Prevention Research Institute in Lyon, carried out a review of data from 290 prospective observational studies and 172 randomised trials looking at the effects of vitamin D levels on health outcomes, excluding bone health, up to December 2012. 
  
 'Discrepancy' 
  
 A large number of the observational studies suggested that there were benefits from high vitamin D - that it could reduce the risk of cardiovascular events by up to 58%, diabetes by up to 38% and colorectal cancer by up to 33%. 
  
 But the results of the clinical trials - where participants were given vitamin D supplements - found no reduction in risk, even in people who started out with low vitamin D levels. 
  
 And a further analysis of recent randomised trials found no positive effect of vitamin D supplements on diseases occurring. 
  
 Prof Autier said: "What this discrepancy suggests is that decreases in vitamin D levels are a marker of deteriorating health. 
  
 What is a vitamin D deficiency? A vitamin D level less than 25nmol/L in the blood is a deficiency, but experts increasingly believe that lower than 60nmol/L can also be damaging to health. Most people get enough vitamin D by being exposed to the sun for 10 to 15 minutes a day. A small amount of vitamin D also comes from foods such as oily fish and dairy products. Recently England's chief medical officer said free vitamins should be given to all young children because more and more of them were being diagnosed with the bone disease rickets, lack of calcium and other bone and muscle diseases. 
  
 "Ageing and inflammatory processes involved in disease occurrence... reduce vitamin D concentrations, which would explain why vitamin D deficiency is reported in a wide range of disorders." 
  
 High risk 
  
 In the UK, vitamin D supplements are recommended for groups at higher risk of deficiency, including all pregnant and breastfeeding women, children under five years old, people aged over 65, and people at risk of not getting enough exposure to sunlight. 
  
 People with dark skin, such as people of African-Caribbean and South Asian origin, and people who wear full-body coverings, as well as pale-skinned people are also known to be at higher risk. 
  
 In recent years, there has been a four-fold increase in admissions to UK hospital with rickets - a disease that causes bones to become soft and deformed. 
  
 Dr Colin Michie, consultant senior lecturer in paediatrics and chair of the nutrition committee at the Royal College of Paediatrics and Child Health, said the review had little to contribute to the problem in the UK because it excluded the measurement of bone health. 
  
 "It has been known for almost a century that vitamin D supplements given to those with deficient vitamin D levels results in improved bone health, preventing hypocalcemic seizure and rickets." 
  
 He added that it was important to provide appropriate supplements, such as vitamin D, to improve bone health. 
  
 More research 
  
 Peter Selby, consultant physician and honorary professor of metabolic bone disease at Manchester Royal Infirmary, said the French review was limited. 
  
 "It could very well be that the apparent negative results of this study have been obtained simply because they have not been looking at people with sufficient degree of vitamin D insufficiency to have any meaningful biological effect." 
  
 But he said the authors were right to say that more interventional research looking at disease outcomes was necessary. 
  
 The Scientific Advisory Committee on Nutrition (SACN), an independent group of scientific experts who advise the government on nutrition, is currently reviewing the dietary recommendations for vitamin D for all population groups in the UK. 
  
 Their report on vitamin D is expected to go out for public consultation in 2014. |||||
Output:
Is there any point in healthy people taking vitamin D supplements? New research suggests that while low levels of the "sunshine vitamin" are linked to many illnesses, the deficiency is a result, not a cause of sickness, reports Reuters. French researchers who reviewed hundreds of other studies were unable to find any link between taking vitamin D supplements and having a reduced risk of contracting illnesses including cancer, diabetes, and cardiovascular disease. The review suggests "decreases in vitamin D levels are a marker of deteriorating health," the lead researcher says. Experts not involved in the study say that while it shows that more long-term studies of the vitamin's effects are needed, it shouldn't be a reason for people ceasing to take supplements—especially among groups at risk of deficiency, including older people, pregnant and breastfeeding women, young children, and people with darker skin. The French study also failed to look at bone health, critics note. "It has been known for almost a century that vitamin D supplements given to those with deficient vitamin D levels results in improved bone health, preventing hypocalcemic seizure and rickets," a leading pediatrician tells the BBC.