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This sort of article can make a good starting point  - what questions does it raise? Then off you go to key-word search web of science/pubmed.

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By Mary O'Connor
BBC News

Folic acid is to be added to UK flour to help prevent spinal birth defects in babies, the government has announced.

It is thought that adding folic acid to flour could prevent up to 200 birth defects a year.

The new rules will only apply to non-wholemeal wheat flour, with gluten-free foods and wholemeal flour exempt.

Women are advised to take 400 micrograms of folic acid a day for at least a month before conception and up to the 12th week of pregnancy.

But about half of pregnancies are unplanned and women are not always aware they should take the supplement - or forget to.

Since World War Two, the UK's non-wholemeal flour has been fortified with iron, calcium and two other B vitamins - thiamin and niacin.

It's taken years of debating to reach this decision.

That's because the gains need to be carefully weighed against any potential harms.

Adding folic acid to flour used in common foods, such as bread, will mean dosing the masses.

Clearly, getting enough folic acid around conception and during pregnancy is important for cutting the risk of women having babies with spina bifida or other neural tube defects.

But most other people already get their required amount of folate - the natural form of the vitamin - from a normal diet.

There was a concern that for some people, particularly the elderly, boosting folic acid might have unintended negative consequences, such as covering up the symptoms of vitamin B12 deficiency.

But the government's independent advisory body has looked at all the evidence and is satisfied that fortification is the right thing to do for society as a whole.

Prime Minister Boris Johnson said folic acid-fortified flour would be "a quick, simple win" to enhance a baby's development, as well as helping to boost the health of UK adults.

Health and Social Care Secretary Sajid Javid said preventing life-threatening health problems like spina bifida would mean fewer people needing hospital treatment.

The government said it did not anticipate the move would require a major overhaul for industrial-scale flour producers - the B vitamin would need to be listed on the labelling of all foods made with flour.

Kate Steele, chief executive of Shine, a charity providing specialist support for people affected by spina bifida and hydrocephalus and which has campaigned for mandatory fortification of flour for more than 30 years, said she was "delighted" by the decision.

"In its simplest terms, the step will reduce the numbers of families who face the devastating news that their baby has anencephaly and will not survive," she said.

"It will also prevent some babies being affected by spina bifida, which can result in complex physical impairments and poor health.

"This is truly a momentous day''.

Good dietary sources of folate

spinach, kale, Brussels sprout, cabbage, broccoli

beans and legumes (eg., peas, blackeye beans)

yeast and beef extracts

oranges and orange juice

wheat bran and other wholegrain foods

poultry, pork, shellfish and liver

fortified foods (eg some breakfast cereals)

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Folic acid to be added to UK flour to help prevent birth defects

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By Mary O'Connor BBC News Folic acid is to be added to UK flour to help prevent spinal birth defects in babies, the government has announced. It is thought that adding folic acid to flour could prevent up to 200 birth defects a year.

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News articles like these highlight one or more studies - here you'd evaluate one of those articles, and see what questions it raises for your next step.

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A new study from top academics has claimed 100,000 obesity cases have been prevented due to a ban on junk food advertising on the Transport for London (TfL) network.

But is it true?

Since February 2019, adverts for foods high in calories from sugar or fat, or high in salt, have been banned across the TfL network.

Food and drink brands, restaurants, takeaways and delivery services are only allowed to place adverts that promote healthier products - rather than simply publicising brands.

The measures were introduced to help tackle child obesity, the mayor of London confirmed when the project was launched.

The scheme received 82% support during a public consultation.

What did the study find?

The ban directly led to 94,867 fewer cases of obesity than expected, a 4.8% decrease, analysis by the University of Sheffield and the London School of Hygiene & Tropical Medicine (LSHTM) found.

The same study found the policy has led to 2,857 fewer cases of diabetes, and 1,915 fewer cases of cardiovascular disease.

Decreases this large would save the NHS an estimated £218m over the lifetime of the current population, the researchers said.

These conclusions are based on a previous study into the purchasing habits of nearly 1,000 Londoners following the advertising ban, compared to 1,000 people in the north-east of England.

The initial research, published in February, estimated the ban contributed to a 1,001 calorie decrease in people's weekly shopping. Purchases of food containing high levels of fat, sugar or salt also decreased.

And the effect for the subgroup of people "where the main food shopper reported public transport use" was an even greater reduction, of 1,307 calories.

Academics at the University of Sheffield and LSHTM then used a "microsimulation model" to estimate what would happen to people's health if this reduction in buying junk food happened in all London households.

What do critics say?

"All modelling is assumptions and this makes some very heroic assumptions," according to one professor who spoke to the BBC anonymously.

Others put it more bluntly.

"This modelling study is one of the worst pieces of junk science I have ever come across in a journal," said Christopher Snowdon, from the free market think tank the Institute of Economic Affairs.

"It builds on an earlier modelling study which falsely claimed that the advertising ban caused Londoners to consume 1,000 fewer calories."

The report "makes various back-of-the-envelope calculations based on that factoid", Mr Snowdon said.

Critics can point to NHS data that shows child obesity rates, which the advert ban was introduced to tackle, have increased in London faster than average since the start of the junk food advertising ban.

What do supporters say?

Mayor of London Sadiq Khan said: "Advertising undoubtedly plays a significant role in promoting and encouraging the consumption of less healthy foods.

"This study, which builds on research from earlier this year, demonstrates yet again that the ground-breaking restrictions we introduced could not only influence behaviour and ultimately save lives but could directly save our NHS hundreds of millions of pounds.

"I am determined to continue this work to improve the health of Londoners, alleviating some of the burden on our overstretched health service and building a better London for everyone."

Dr Chloe Thomas, the lead author of the study, said the research had "shown what an important tool advertising restrictions can be in order to help people lead healthier lives without costing them more money".

"We hope that demonstrating the policy's significant benefits in preventing obesity and the diseases exacerbated by obesity will lead to it being rolled out on a national scale," she added.

Dr Oliver Mytton said the report that found households were buying 1,001 fewer calories of food - which he worked on - is "our best estimate to what the impact of the ban has been".

"It's certainly not 100% accurate, but it's not a rubbish estimate either," said Dr Mytton, a public health consultant at the UCL Great Ormond Street Hospital Institute for Child Health.

"The nature of science is there is always a degree of uncertainty."

But Dr Mytton, an expert in microsimulations, believes the health impact of the advertising ban is clear.

"There is a body of information that links advertising to purchasing and eating of food," he said.

"From there the impact on calorie consumption, its effect on body weight and health outcomes, is pretty predictable.

"This study is still pushing things in the right direction."

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TfL junk food advert ban: Has the policy cut obesity?

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A new study from top academics has claimed 100,000 obesity cases have been prevented due to a ban on junk food advertising on the Transport for London (TfL) network. But is it true? Since February 2019, adverts for foods high in calories from sugar or fat, or high in salt, have been banned across the TfL network.

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An example of an article that highlights a specific study - where will evaluation of that one take you?

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Exercise answer: Research shows it’s how often you do it, not how much: We all know exercise is important, but is it better to do a little every day, or a lot a few times a week?

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New research indicates a little bit of daily activity is more beneficial than longer periods of exercise spread out across the week -- and happily, it also suggests you don’t have to put in a mountain of work every day.

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Not one for the faint-hearted, as they say - but interesting ethical considerations.

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Gene-editing technologies have breathed life into the languishing field of xenotransplantation.

Pale on its bed of crushed ice, the lung looks like offal from a butcher's counter. Just six hours ago, surgeons at the University of Maryland's medical school in Baltimore removed it from a hefty adult pig and, with any luck, it will soon be coaxed back to life, turning a rich red and resuming its work in the chest of a six-year-old baboon.

An assistant brings the lung to Lars Burdorf and his fellow surgeons, who currently have their hands in the baboon's splayed chest. The team then begins the painstaking process of connecting the organ to the baboon's windpipe and stitching together the appropriate arteries and blood vessels. But this 5-hour, US$50,000 operation is just one data point in a much longer experiment - one that involves dozens of labs and decades of immunological research and genetic engineering to produce a steady and safe source of organs for human transplantation. If the baboon's immune system tolerates this replacement lung, it will be a sign that the team is on the right track.

Robin Pierson heads the Maryland lab, which has performed about 50 pig-to-primate transplants like this one to test different combinations of genetic modifications in the pig and immune-suppressing drugs in the primate. Even so, the team has not had a primate survive for longer than a few days. The complexities of the immune system and the possibility of infection by pig viruses are formidable and drove large companies out of the field in the early 2000s.

That trend may now be reversing, thanks to improved immunosuppressant drugs and advances in genome-editing technologies such as CRISPR/Cas9. These techniques allow scientists to edit pig genes, which could cause rejection or infection, much more quickly and accurately than has been possible in the past. In October, eGenesis, a life-sciences company in Boston, Massachusetts, announced that it had edited the pig genome in 62 places at once.

Some researchers now expect to see human trials with solid organs such as kidneys from genetically modified pigs within the next few years (see 'Choice cuts'). United Therapeutics, a biotechnology company in Silver Spring, Maryland, has spent $100 million in the past year to speed up the process of making transgenic pigs for lung transplants - the first major industry investment in more than a decade. It says that it wants pig lungs in clinical trials by 2020. But others think that the timeline is unrealistic, not least because regulators are uneasy about safety and the risk of pig organs transmitting diseases to immunosuppressed humans.

"I think we're getting closer, in terms of science," says transplant surgeon Jeremy Chapman of the University of Sydney's Westmead Hospital in Australia. "But I'm not yet convinced we've surpassed all the critical issues that are ahead of us. Xenotransplantation has had a long enduring reality that every time we knock down a barrier, there's another one just a few steps on."

Surgeons have been attempting to put baboon and chimpanzee kidneys into humans since at least the 1960s. They had little success - patients died within a few months, usually because the immune system attacked and rejected the organ. But the idea of xenotransplantation persisted. It could, proponents say, help to save the lives of the tens of thousands of people around the world who die each year while waiting for a suitable human donor. And having a steady supply of farm-grown organs would allow doctors to place recipients on immunosuppressant drugs days ahead of surgery, which should improve survival rates.

This discovery and other advances in transplantation medicine made the problem seem more tractable to big pharmaceutical companies. In 1996, Novartis in Basel, Switzerland, began to invest heavily in xenotransplantation research, says Geoffrey MacKay, who was the firm's business director for transplants and immunology at the time and oversaw the xenotransplantation effort. "They wanted to not only put a dent into the organ shortage but really solve it via transgenic pigs." MacKay is currently interim chief executive at eGenesis.

Novartis initially planned to spend more than $1 billion on xenotransplantation, including both scientific research and planning the infrastructure that would be needed to grow pigs in germ-free facilities around the world. Other companies put some skin in the game, including Boston-based Genzyme and PPL Therapeutics, the British company that collaborated in the creation of Dolly, the first cloned sheep. Regulators such as the US Food and Drug Administration (FDA) began to draw up the guidance and standards that companies would need to meet before the technology could be moved into people.

But the immune system turned out to be much more complex than anticipated, and baboons that received pig organs never survived longer than a few weeks, even when the researchers were able to suppress α-gal production with drugs. A second major concern, especially to regulators, was the risk of infection. Even if pigs could be kept entirely sterile, the pig genome is sprinkled with dozens of dormant porcine endogenous retroviruses (PERVs), and studies conflicted as to whether these could become active in humans.

The challenges proved too daunting, and in the early 2000s Novartis killed its xenotransplantation programme, reshuffling or laying off its researchers. Other companies followed suit. It became, Pierson says, "the third rail of biotech to discuss xenotransplantation as a business plan".

"I think people are coming around to look at xenotransplantation in a more-favourable light knowing that we have strong safety data," says LCT research lead Jackie Lee. Diatranz Otsuka Limited, in Auckland, is now running the programme.

Solid organs still pose a challenge. The handful of researchers who have continued to work with them have solved some of the problems that vexed Novartis, such as identifying other key pig antigens and the correct combinations of immunosuppressant drugs. But different organs have different problems: kidneys may be safer than hearts, for instance. Lungs, as Pierson's team has discovered, are extremely difficult to transplant, because they have extensive networks of blood vessels, which provides more opportunities for primate blood to meet pig proteins and to coagulate. Pierson's current trials use lungs from an α-gal-knockout pig that includes five human genes. The baboon is treated with a combination of four immunosuppressant drugs.

But the process is slow, Cooper says. It generally takes several generations of breeding to knock out both copies of just one given gene in a pig. Deleting multiple genes or swapping them for their human counterparts takes many more generations, because every litter contains pigs with different combinations of the modified genes.

Eventually, gene editing might even eliminate the need for immunosuppression, says Bernhard Hering, a transplant surgeon at the University of Minnesota in Minneapolis. His group is using CRISPR to create pig islets that could be transplanted without the need for drugs. Partly because of LCT's success with encapsulated islets, many are hopeful that islet cells will be the first genetically modified tissue to make it into clinical trials, paving the regulatory pathway for the more-difficult organs. A non-profit organization has built a germ-free facility in which to raise Hering's pigs.

The gene-editing advances have brought new investment into the field. In 2011, United Therapeutics acquired Revivicor for about $8 million and announced an ambitious plan to start clinical trials of gene-edited pig lungs by the end of the decade. The company's co-chief executive, Martine Rothblatt, secured land in North Carolina for a farm that could produce 1,000 pig organs per year and says she expects to break ground by 2017. The facility's elaborate plans include solar panels and helicopter landing pads to help speed fresh organs to those in need.

In 2014, United Therapeutics formed a $50-million partnership with the biotech firm Synthetic Genomics (SGI) in La Jolla, California, founded by genome-sequencing pioneer Craig Venter. Rather than simply knocking out antigens, SGI is also engineering tissues that sidestep rejection in a different way - such as pig cells that produce surface receptors that act as 'molecular sponges' and sop up human immune signalling factors that would otherwise attack the organ. CRISPR and other methods also allow the researchers to make tweaks such as lowering a gene's expression rather than deleting it completely, says Sean Stevens, head of SGI's mammalian synthetic-biology group. In September, United Therapeutics committed another $50 million.

Peter Cowan, an immunologist at St Vincent's Hospital in Melbourne, Australia, is taking a different approach. His group has made pigs that generate antibodies against human immune cells. In their design, the antibodies would be made only by transplanted liver cells, ensuring that the immune system is suppressed just around the organ.

eGenesis was founded in April by bioengineer Luhan Yang and geneticist George Church of the Wyss Institute and Harvard University in Cambridge, Massachusetts. MacKay says that the firm plans to begin transplanting organs into primates next year. To that end, Church says that the company has made embryos that have more than 20 genetic alterations to cell-surface antigens and other factors and is ready to implant the embryos into female pigs. One of its first publications used CRISPR to inactivate 62 occurrences of PERV genes in pig kidney cells. The researchers have since transferred the cells' nuclei into pig embryos.

Incidentally, few researchers in the field see the PERV problem as a major safety concern. The virus replicates poorly in human tissues and the risk of spreading it is virtually non-existent, says Jay Fishman, an infectious-disease specialist at Massachusetts General Hospital in Boston. He says that researchers have tracked dozens of people who received unregulated porcine skin grafts, and none seems to have developed disease.

But dealing with PERVs may be a regulatory necessity. The FDA said in an e-mail to Nature that it is still concerned about the possibility of disease caused by PERVs. There are other pathogens to worry about, too. Most major epidemics start with an animal pathogen that jumps to humans, warns Peter Collignon, an infectious-disease scientist at the Australian National University in Canberra. "If you want to do the perfect experiment for finding new novel viruses and letting them multiply, this is it."

Unless xenotransplants are proved to be extremely safe, the FDA suggests that they be limited to people with life-threatening conditions who have no other options. It will be even harder to get organs from genetically modified pigs to market, the agency says, because regulators must approve both the genetic construct used to make the animal and the organ itself.

Even if safety can be assured, questions remain about whether pig organs would work correctly in their new home, Chapman says. It is unclear whether a pig kidney would, for instance, respond to the human hormones that regulate urination, or whether proteins produced by a pig liver would interact correctly with human systems. And because pigs live for only about ten years, their organs might not survive a human lifetime. Even using a xenotransplant as a 'bridge' until a suitable human donor is found will be difficult. After a heart transplant, for instance, fibrous tissue forms around the new organ, making second transplants very difficult, Chapman says.

Given the long list of known hurdles, the surprise setbacks that researchers encounter along the way can be particularly disheartening. About half an hour after its surgery at the University of Maryland, the baboon with a pig's lung woke up in a cage wearing a small vest that monitored its vital signs. The lung functioned well overnight and was even able to provide enough oxygen to the animal when blood flow to its other lung was temporarily blocked. But the next day, the animal became ill and had to be killed. That was unexpected, Pierson says, because the pig's multiple genetic modifications seem to have worked well with the baboon's immune system. A post-mortem examination revealed that fluid had accumulated in the lung and the organ had developed blood clots. Like so many other aspects of xenotransplantation, Pierson says, "this is a problem that we are still learning about".

About this article

Further reading

Steffi Friedrichs

, Yoko Takasu

, Peter Kearns

, Bertrand Dagallier

, Ryudai Oshima

, Janet Schofield

& Catherine Moreddu

Transgenic Research (2019)

Journal of Agricultural and Environmental Ethics (2018)

Cara Ellis

, Adam Ramzy

& Timothy J. Kieffer

Nature Reviews Gastroenterology & Hepatology (2017)

Ethical Theory and Moral Practice (2017)

Kristina L. Penniston

, Sutchin R. Patel

, Denise J. Schwahn

& Stephen Y. Nakada

Urolithiasis (2017)

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New life for pig-to-human transplants - Nature

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Gene-editing technologies have breathed life into the languishing field of xenotransplantation. Pale on its bed of crushed ice, the lung looks like offal from a butcher's counter.