Why has it been so hard to make glowing plants?

Refers to: https://www.technologyreview.com/s/601884/why-kickstarters-glowing-plant-left-backers-in-the-dark/

A peer-reviewed 2010 academic study showed it's possible to make glowing plants (See below from 1).

They claimed to have (1),

'generated the first truly autonomously luminescent (autoluminescent) transplastomic plants, containing a fully functional bacterial luciferase pathway, which emits visible light detectable by the naked eye'

Antonio Regalado writes in the MIT Technology Review (2),

'the scientist who carried out that work, Alexander Krichevsky, says it took him three years leading a lab at a well-equipped university, SUNY Stonybrook, to do it’

In the age of the Anthropocene, the Kickstarter Glowing Plants project's premise was altogether too beguiling, create glowing trees to light streets. However, that it took several years of effort for a dedicated, well-equipped academic lab to make one dimly glowing plant shows it takes a lot more cutting edge molecular biology than this team seems to have bargained for and highlights their scale of exaggeration (2).

'Krichevsky has since started his own glowing plant company, Bioglow, and says he has spent another three years trying to make the plants bright enough to interest consumers, a task which is ongoing. He says it was obvious to anyone in plant biology that Taxa’s timelines were unrealistic. “I was surprised by the promises they made. I thought, maybe they know something I don’t. Now I see that it is delusional,” he says. “They didn’t deliver anything for three years and I strongly doubt they ever will.”'

In hindsight, their Kickstarter campaign was a casualty of the two opposing yet irresistible forces that drove it in the first place. A biting-off-more-than-one-can-chew mindset within their team and the investors' scientific babes-in-arms credulousness.

Bioluminescence is an ancient biological property found in all major phyla on land and water including bacteria, fungi, fireflies, squid, earthworms and fishes. Essential bioluminescence components are Luciferin and Luciferase. Depending on the type of luciferin, bioluminescence can emit light ranging from 400nm to 700nm (3), i.e., colors ranging from blue, green, yellow, pink to red. In the presence of ATP and oxygen, the luciferase enzyme converts one molecule of luciferin protein to one of oxyluciferin, a process that generates one photon of light. Since a standard 100W light bulb can emit quintillions of photons per second, the 2010 report shows that making just one small plant dimly glow requires tremendous feats of genetic engineering.

Now renamed Taxa Biotechnologies, the Glowing Plant project team's penchant for inflated claims shows in the way they obviously felt no qualms about appropriating an image from the first genetically engineered glowing plant reported all the way back in 1986 and using it without attribution on their merchandise (see below from 4, 5, also pointed out by 6).

Unlike the original 1986 report which inserted only the luciferase enzyme into the tobacco plant genome and thus required luciferin supplied from outside to drive the 'glow' reaction, Krichevsky et al (1) made their plant autonomously bioluminescent by inserting genes for both luciferin and luciferase enzyme into it, using technology similar to the one the Glowing Plant project needed to use (1). For the Glowing Plants project to skirt loopholes in US law regarding Genetically modified organism (GMO) and ensure their glowing plants-to-be wouldn't be subject to regulation at all meant using the Gene gun to introduce the 'glow' genes into plants (2). Essentially this is an air pistol that shoots the gene-coated gold pellet into the intended target cell, in this case a plant cell. Given the amount of money they raised, ~half a million US dollars (2), other than absence of focus and determination, no reason why they couldn't have at least replicated Krichevsky et al's efforts over the 3 years they'd been working on this project.

Bibliography

1. Krichevsky, Alexander, et al. "Autoluminescent plants." PloS one 5.11 (2010): e15461. http://journals.plos.org/plosone...

2. MIT Technology Review, Antonio Regalado, July 15, 2016. Why the promise of a plant that glows has left backers in the dark

3. Widder, Edith A. "Bioluminescence in the ocean: origins of biological, chemical, and ecological diversity." Science 328.5979 (2010): 704-708. https://www.researchgate.net/pro...

4. Ow, David W., et al. "Transient and stable expression of the firefly luciferase gene in plant cells and transgenic plants." Science 234 (1986): 856-859. https://www.researchgate.net/pro... Glowing Plant | Merchandise

5. Glowing Plant | Merchandise

6. Illumination blog, Kevin M. Folta, July 19, 2016. Unfilled Glowing Plant Promises Harm Science Perception

Thanks for the R2A, Jonathan Brill.

https://www.quora.com/Why-has-it-been-so-hard-to-make-glowing-plants/answer/Tirumalai-Kamala

How much of an impact do Fourth of July fireworks in the US as a whole have on pollution and/or global warming?

A pretty flash followed by a bang, my deceptively benign childhood memory of fireworks, as I suspect it may be for many others. In reality, fireworks contain rather nasty chemicals, cause fires, deaths and injuries both during their production and use, create major noise pollution both for humans and their pets, and are a major public health hazard provoking acute health crises for people with chronic heart and lung conditions. Polluting air, water and soil around the factories where they're made, when lit up, fireworks release particulate matter (PM), ozone, harmful gases (sulfur dioxide, carbon dioxide, carbon monoxide) and trace elements.

Unfortunately fireworks are usually set off only at specific times of the year, making it easier to disregard their impact on the environment and on health. A global phenomenon, New Year's Eve fireworks, France's Bastille Day, Iran's Chaharshanbe Suri, Eid al-Fitr in muslim-dominant countries, Spain's Mascletà and Falles, the UK's Guy Fawkes Night are just a few examples, while probably the two most gluttonous fireworks displays of them all are China and Taiwan's Lantern Festival and India's Diwali (Festival of Lights). Fireworks' pollution is thus also global. If we restrict ourselves to the US July 4th fireworks alone, we risk missing their global environmental and health impact, more so since most US fireworks aren't made locally but rather imported from China.

Fireworks Are A Source Of Perchlorates, A Persistent, Potent Thyroid Disruptor

Recognized as a public health concern since 2011 by the US United States Environmental Protection Agency (EPA) (1), Perchlorate are inorganic anions used in a variety of explosive materials including solid rocket propellants, ammunition and fireworks. Readily water-soluble, perchlorate anions persist stably in the environment for long periods of time. From water, they then seep into all variety of biomass (plants and animals) (2). Potent thyroid disruptors, perchlorates can enter the body through skin, oral and respiratory routes. Competitively inhibiting uptake of iodide by the thyroid, they can cause reduction in thyroid hormones. Released into the atmosphere following fireworks explosions, extent of local perchlorate contamination depends on fireworks type, amount and duration, wind direction and velocity, and other local weather conditions at the time. Perchlorate contamination in surface and ground water has now been observed the world over from the US to Japan, China, Korea, India.

• One study in Long Island, New York, found local post-July 4th perchlorate levels to be as much as 18X higher than background levels, even at sites several kilometers away from known displays (3).

Obviously, as with other environmental contaminants, greater the exposure, greater the risk. Chronic perchlorate exposure is thus likelier for those who make fireworks. The world's largest fireworks manufacturing country, China supplies ~98% of fireworks imported by the US (4), and most fireworks used in the US are indeed imported.

• One study found surface water perchlorate levels as high as 54.4µg/ml near a Chinese fireworks manufacturing area (5), >7700X higher than the human exposure level of 7ng/kg/day the US EPA deems to be of minimal risk (6).
• Blood samples of babies and adults in China's major fireworks manufacturing hub, Nanchang city, contained detectable levels of perchlorate (1 to 2µg/kg/day) (7) much higher than the US EPA's reference dose (7ng/kg/day).
• Soil around Indian fireworks factories has been found heavily polluted with perchlorates (8).

Chemical contamination around firework factories also affect both microbial abundance and diversity in the local soil and water (9), meaning long-term environmental cost.

Making & Using Fireworks Causes Deaths & Injuries, An Eminently Avoidable Public Health Problem

Fireworks production-related deaths and injuries are commonplace, especially in countries like India where fireworks factories frequently use illegal child labor since small, nimble fingers speed up the assembly of certain fireworks (see below from 10, 11, 12).

In the US more fires are reported on July 4th than any other day in the year (13). However that blunt statistic doesn't reveal the full scale of the cost of fireworks-related fires. Fire and emergency services are hugely expensive in the US and have become even more so since the Great Recession. In its wake, as cities struggled even more than in the past to provide such services, Wall Street and private equity firms rode to the rescue, of course only at huge cost to the taxpayer (14). Since fireworks are pure indulgence, cost of the inevitable fires they leave in their wake are an unnecessary extremely costly burden on tax-paying communities already stretched to their limits.

Inevitable firework-related burns, other injuries and even deaths are another cost, with young boys disproportionately affected (see below from 15, 16, 17, 18).

Apart From Noise Pollution, Fireworks Are A Source Of Acute Health Hazards, Especially For Those With Heart & Lung Problems

Albeit temporarily, fireworks create tremendous noise pollution that can be quite traumatic for hapless pets (19) as well as wild fauna (20, 21). They also severely reduce ambient air quality (22, 23, 24), to such an extent that some people can be hospitalized or even die. India offers compelling examples of such odious, entirely preventable trends. As it becomes wealthier, bursting firecrackers during Diwali has become a surrogate marker for disposable wealth, literally changing the ancient Festival of Light into utter Cacophony. On and around Diwali, the very air's literally a sulfurous smog in each and every one of India's teeming cities. Imagine the plight of those with chronic heart and lung conditions in the aftermath of non-stop fireworks for ~ 24 hours. No surprise studies show fireworks induce acute health crises in such patients (25, 26, 27).

Globally, fireworks harm the environment, and the health of humans and animals. Aren't they also a case of literally burning money? To paraphrase Obelix, 'we humans are crazy'.

Bibliography

1. https://www.epa.gov/sites/produc...

2. Sijimol, M. R., and Mahesh Mohan. "Environmental impacts of perchlorate with special reference to fireworks—a review." Environmental monitoring and assessment 186.11 (2014): 7203-7210.

3. Munster, Jennie, et al. "The fallout from fireworks: perchlorate in total deposition." Water, air, and soil pollution 198.1-4 (2009): 149-153. https://www.researchgate.net/pro...

4. https://www.cpsc.gov//Global/Res...

5. Wu, Qian, et al. "Perchlorate in tap water, groundwater, surface waters, and bottled water from China and its association with other inorganic anions and with disinfection byproducts." Archives of environmental contamination and toxicology 58.3 (2010): 543-550. http://s3.amazonaws.com/academia...

6. Perchlorate | Drinking Water Contaminants

7. Zhang, Tao, et al. "Perchlorate and iodide in whole blood samples from infants, children, and adults in Nanchang, China." Environmental science & technology 44.18 (2010): 6947-6953.

8. Isobe, Tomohiko, et al. "Perchlorate contamination of groundwater from fireworks manufacturing area in South India." Environmental monitoring and assessment 185.7 (2013): 5627-5637.

9. Dhasarathan, P., P. Theriappan, and C. Ashokraja. "Microbial diversity in firework chemical exposed soil and water samples collected in Virudhunagar district, Tamil Nadu, India." Indian journal of microbiology 50.1 (2010): 46-49. http://www.ncbi.nlm.nih.gov/pmc/...

10. http://www.jugendeinewelt.at/fil...

11. http://www.ncpcr.gov.in/view_fil...

12. Frontline, S. Durairaj, August 29, 2009. Danger zone

13. Fireworks

14. The New York Times, Danielle Ivory, Ben Protess, Kitty Bennet, June 25, 2016. When You Dial 911 and Wall Street Answers

15. Firework Statistics

16. https://www.cpsc.gov/Global/Rese...

17. Canner, Joseph K., et al. "US emergency department visits for fireworks injuries, 2006–2010." journal of surgical research 190.1 (2014): 305-311. https://www.researchgate.net/pro...

18. Moore, Justin Xavier, Gerald McGwin, and Russell L. Griffin. "The epidemiology of firework-related injuries in the United States: 2000–2010." Injury 45.11 (2014): 1704-1709. http://www.sciencedirect.com/sci...

19. Levine, Emily D., Daniela Ramos, and Daniel S. Mills. "A prospective study of two self-help CD based desensitization and counter-conditioning programmes with the use of Dog Appeasing Pheromone for the treatment of firework fears in dogs (Canis familiaris)." Applied Animal Behaviour Science 105.4 (2007): 311-329. http://psicovet.com.br/wp-conten...

20. Shamoun-Baranes, Judy, et al. "Birds flee en mass from New Year’s Eve fireworks." Behavioral Ecology 22.6 (2011): 1173-1177. Birds flee en mass from New Year’s Eve fireworks

21. Pedreros, Eduardo, et al. "Observations of the effect of a New Year’s fireworks display on the behavior of the South American sea lion (Otaria flavescens) in a colony of central-south Chile." Marine and Freshwater Behaviour and Physiology 49.2 (2016): 127-131.

22. Saha, Upal, et al. "Effects of air pollution on meteorological parameters during Deepawali festival over an Indian urban metropolis." Atmospheric Environment 98 (2014): 530-539. https://www.researchgate.net/pro...

23. Pervez, Shamsh, et al. "Chemical speciation of aerosols and air quality degradation during the festival of lights (Diwali)." Atmospheric Pollution Research 7.1 (2016): 92-99

24. Seidel, Dian J., and Abigail N. Birnbaum. "Effects of Independence Day fireworks on atmospheric concentrations of fine particulate matter in the United States." Atmospheric Environment 115 (2015): 192-198. https://www.researchgate.net/pro...

25. Pal, Raina, et al. "The Effects of Fireworks on Ambient Air and Possible Impact on Cardiac Health during Deepawali Festival in North India." World Heart Journal 5.1 (2013): 21. The Effects of Fireworks on Ambient Air and Possible Impact on Cardiac Health during Deepawali Festival in North India

26. Gouder, Caroline, and Stephen Montefort. "Potential impact of fireworks on respiratory health." Lung India: official organ of Indian Chest Society 31.4 (2014): 375. http://www.lungindia.com/temp/Lu...

27. Chakraborty, Ananya. "KEYWORDS Respiratory health, Diwali, Dyspnea, Hospitalization." HOSPITALIZATIONS DUE TO RESPIRATORY PROBLEMS DURING DIWALI FESTIVAL IN A TERTIARY CARE HOSPITAL IN SOUTH INDIA. 94087 (2016). http://www.jebmh.com/data_pdf/11...

https://www.quora.com/How-much-of-an-impact-do-Fourth-of-July-fireworks-in-the-US-as-a-whole-have-on-pollution-and-or-global-warming/answer/Tirumalai-Kamala

Is there a pharma boom going on in India?

Stock market fluctuations are too unreliable of an approach to assess an entire industrial sector. Wild speculations apart, something tangible needs to underpin any boom. While Indian Pharma doesn't have upcoming blockbusters, several trends augur its healthy growth.

Indian Pharma: Essentially High Volume-Low Value Global Supplier Of Generics

The world's 3rd largest pharmaceutical industry by volume (10% of global production) but only 14th by value (1.5% of global value) suggests Indian Pharma is a high-volume, low-value proposition (1).

A highly fragmented industry with ~10000 manufacturers, though only ~250 are large-scale, generics dominate Indian Pharma (2), contributing no less than 40% of the US generic drug import for example.

US FDA drug approvals reveal Indian Pharma doesn't have a strong presence in the US new drug market. Of the 96 new drugs it approved in 2013, only 2 were from Indian companies, Lupin's Suprax (active ingredient Cefuroxime) and Alembic's extended release form of anti-depressant desvenlafaxine (3). Thus, a boom can't be justified on hopes of extremely big paydays down the road from expensive new blockbusters selling on drug markets like the USA or the EU. That's simply not Indian Pharma's track record nor is such a US-like process even likely in India, where the government deliberately intervenes with powerful instruments like price controls and compulsory licenses. Through the latter mechanism, if the Indian government deems an originating firm’s listing price unaffordable, it can force them to license their technology to a generic competitor, an extremely strong countervailing force that, though seldom used, hangs like a Damocles sword over the pricing decisions originator firms make when trying to sell their products in India (2, 4), a situation utterly unlike the rampant drug price gouging that's today the norm in the US. This is why drugs in India are among the cheapest in the world (2). Also why Indian Pharma depends on drug volume not price for its profits.

Indian Pharma: Nearing An Inevitable Fork In The Road, Will It Be Super Generics or Biosimilars Next

On the plus side, Indian pharma has built up an enviable infrastructure, with the largest number of US FDA compliant API (Active Pharmaceutical Ingredient) manufacturing plants outside the US (>262), ~1400 WHO GMP-approved plants and 252 European Directorate of Quality Medicines (EDQM) approved plants (1). This capacity has made Indian Pharma a global leader in generics, supplying anti-HIV drugs widely across Africa, Asia, Latin America for example.

Long specializing in generics, Indian pharma faces a major fork in the road in terms of how to expand and diversify in an extremely rapidly changing global pharma landscape. In the ongoing Patent cliff, i.e., patent expiration of blockbuster drugs coming off of patent since 2011 continuing through to 2019, bulk of the patent loss on traditional pharmaceutical drugs has already occurred. Far fewer are expected after 2017. Thus the generics market can only remain a high volume-low value proposition for Indian Pharma.

To gain value, Indian Pharma has to climb the value chain. Developing new drugs all by itself is an extremely costly proposition with very high regulatory burden. New drug development never having been its expertise, options that best leverage Indian Pharma's existing expertise and capability are super generics and biosimilars.

Super Generics represent an incremental innovation to Indian pharma's already well-established generics capability. Though they entail greater regulatory burden, Indian Pharma's making steady inroads into this space (see below from 3, 5).

As generics are to patented drugs so Biosimilar are to biologics (6). Indian Pharma is a relative newcomer in the biologics and biosimilars arena. Making biosimilars, while much more arduous and expensive compared to generics (see below from 7), may yield greater long-term payoff in terms of expanding technological capability which could serve as a launching pad for in-house new drug development down the road.

The ongoing Patent cliff on biologicals (3, see below from 7) is thus a net opportunity for Indian Pharma to enter the biosimilars sector.

Biocon was one of the early entrants, getting approval for its biosimilar CANMab, a remake of Roche's Trastuzumab (Herceptin), a breast cancer drug (8).

Indian Pharma: Steadily Increasing Global Reach Through Mergers, Acquisitions & Joint Ventures

Joint ventures offer a ready-made platform for global pharma to leverage R&D capabilities of well-established Indian entities as Contract research organization (CRO), which helps to considerably reduce cost of new drug development.

In the long-term, expansion of Indian CROs can also help Indian Pharma gain the technological, managerial and regulatory know-how necessary for new drug development, something they currently lack.

Indian Pharma's also been steadily increasing its presence in other countries through acquisitions. A 2016 study reported that 67 Indian companies valued at >US $6 billion made 191 acquisitions across 33 countries from 2000 to 2012 (see tables below from 9, 10).

Indian Pharma: Serious Teething Problems With Clinical Trials

Vast genetic diversity, large 'treatment-naive' population, ~30% urban dwellers with >67 million living in India's 6 largest cities alone plus cost of conducting a clinical trial in India is < 50% of that in the US, all these factors make India an attractive destination for conducting clinical trials. However recent speed-bumps in the form of serious lack of oversight in clinical trial recruitment and informed consent processes (11, 12, 13) have chilled Indian clinical trial activity. A lessons learned mind-set on the part of global pharma and its local regulators and clinical trial partners would help resume trial activity.

Indian Pharma: Dwindling Opportunities For Contract Research For API (Active Pharmaceutical Ingredient) Manufacturing For Europe & USA

Along with China, India leads in API manufacture (see below from 14).

In their efforts to reduce manufacturing costs in Europe and USA, in recent years their Big Pharma increasingly off-loaded API manufacturing to cheaper sites located in places like India. This meant increased scrutiny from foreign regulatory authorities like the US FDA. Indian Pharma leads the pack in number of US FDA warning letters (15). While these setbacks can be and indeed are being interpreted several ways, a pragmatic interpretation would be to see them as a steep but necessary learning curve for Indian Pharma to effectively compete in supplying essential drugs to the US and the EU. Indian Pharma got here by becoming an expert mass manufacturer of API. However, shoring up manufacturing to meet their more stringent regulatory standards is beneficial in the long-term as it improves Indian Pharma's QA/QC, data integrity and compliance standards. High profile warning letters are also beneficial in highlighting a glaring shortcoming in the Indian Pharma regulatory landscape, namely long-standing, tremendous shortage of well-trained and qualified drug inspectors (16, 17), something the Drug Controller General of India, G.N. Singh himself conceded in Jan 2014 is a situation that desperately needs improving (18).

'You cannot equate the Indian regulator with the US one. We are still evolving and it will take us at least 10 years to reach that level. We do not have resources and infrastructure equivalent to those of US FDA. We have a total staff of 650, compared with US FDA's 13,000. Look at the size of our manufacturing industry. The Indian industry is currently supplying generics to over 214 countries.

Also, as a national regulator, the steps that we are taking are voluntary. Manufacturing compliance and quality assurance is a state subject.'

To add to Indian Pharma's woes,

• On 16th July, 2015, the European Commission directed all its member states to suspend national marketing authorization of 700 generic drugs tested and approved by GVK Biosciences (19).
• An early 2016 decision by the US government's made it mandatory for APIs to be manufactured locally for government procurement. According to Live Mint (20), currently ~88% (9 out of 10) of prescriptions dispensed in the US are for generics. India and China are the largest API suppliers to the US. Of the US $2 to 3 billion worth of API that India exports to the US, ~40% is for government purchase so this decision will definitely hit Indian Pharma exports and companies with holdings or subsidiaries in the US.

Thus, Indian Pharma outlook looks bright if it leverages its proven generics expertise into expanding into super generics and biosimilars. Becoming a preferred destination as a clinical trials site and an essential cog in the drug supply chain to the US and the EU, however, need more work in improving its compliance and manufacturing to match their more rigorous standards.

Bibliography

1. Pharma Industry Promotion | Department of Pharmaceuticals

2. http://www.pacificbridgemedical....

3. Suri, F. K., and A. Banerji. "Super Generics—First Step of Indian Pharmaceutical Industry in the Innovative Space in US Market." Journal of Health Management (2016): 0972063415625566.

4. Duggan, Mark, Craig Garthwaite, and Aparajita Goyal. "The market impacts of pharmaceutical product patents in developing countries: Evidence from India." The American Economic Review 106.1 (2016): 99-135. https://openknowledge.worldbank....

5. Stegemann, Sven, et al. "Improved therapeutic entities derived from known generics as an unexplored source of innovative drug products." European Journal of Pharmaceutical Sciences 44.4 (2011): 447-454. https://www.researchgate.net/pro...

6. http://www2.deloitte.com/content...

7. Daubenfeld, Thorsten, et al. "Practitioner’s Section." Journal of Business Chemistry 13.1 (2016): 33. http://www.businesschemistry.org...

8. The Hindu, Jan 18, 2014. Biocon launches cheaper breast cancer drug

9. Trehan, A., Gaikwad, A. Indian Pharma Industry: Trends, Predictions and Challenges. Asia-Pacific Biotech News, 2014: 18: 27-44. Asia Pacific Biotech News - PR NEWSWIRE

10. Jayanthi, Bhargavi, S. N. V. Sivakumar, and Arunima Haldar. "Cross-border Acquisitions and Host Country Determinants: Evidence from Indian Pharmaceutical Companies." Global Business Review 17.3 (2016): 684-69.

11. Tirumalai Kamala's answer to Should we have an international forum to resolve clinical trial mishaps?

12. Tirumalai Kamala's answer to Is it true that Bill Gates faced trial in India for illegally testing tribal children with vaccines?

13. Tirumalai Kamala's answer to Do western drug companies test more dangerous drugs on the poor in India, and should they be held accountable?

14. CHEManager Europe, April 2012. Will API Manufacturing Move out of India and China? http://thomsonreuters.com/conten...

15. Business Standard, Aneesh Phadnis, May 5, 2016. Indian drug units violate most US pharma regulators' rules

16. Kadam, Abhay B., et al. "Correcting India’s chronic shortage of drug inspectors to ensure the production and distribution of safe, high-quality medicines." (2016). http://www.allysonpollock.com/wp...

17. A report on fixing India's broken drug regulatory framework. Dinesh S. Thakur, Prashant Reddy T. June 4, 2016. http://spicyip.com/wp-content/up...

18. Business Standard, Sushmi Dey, Jan 30, 2014. If I follow US standards, I will have to shut almost all drug facilities: G N Singh

19. European Medicines Agency - Human medicines - GVK Biosciences

20. Live Mint, Reghu Balakrishnan, Shine Jacob, Feb 6, 2016. No major impact on API import ban in US

https://www.quora.com/Is-there-a-pharma-boom-going-on-in-India/answer/Tirumalai-Kamala

Is Diet Coke (or other diet sodas) good or bad for dieting and weight loss? Does diet soda cause people to gain weight? If so, why?

Sweet taste without the calories sounds like a perfect example of no pain, all gain but unfortunately cumulative data suggests otherwise. A poster child for unintended consequences, diet soda (Diet drink) typically contains a type of non-caloric artificial sweetener, Sugar substitute called Aspartame, e.g., NutraSweet or Equal (sweetener). Unintended consequences in the form of not just weight gain but also increased risk of Cardiovascular disease, Diabetes mellitus type 2, Hypertension, Metabolic syndrome, all vigorously disputed of course (see some examples in references 1, 2), which brings us to the glaring caveat we need to keep front and center when considering the science about artificial sweeteners. Historically the food and beverage industry has funded nutrition research so substantially, the ensuing entrenched conflict of interest renders the phrase 'nutrition science' an oxymoron (3).

North America currently leads in sales and consumption of diet beverages (see below from 4).

Artificial sweetener consumption patterns tend to change rapidly in response to widespread perception of harm attendant to one type of artificial sweetener or another. US artificial sweetener consumption for example moved from cyclamate in the 1960s to Saccharin, e.g., Sweet'n Low, to aspartame which reigned supreme for several decades until being upstaged in the 2010s by Sucralose, e.g., Splenda, mainly because it's highly stable in food (5) while Acesulfame potassium (Ace-K), e.g., Sunett, Sweet & Safe, Sweet One, is also increasing in use. Pepsi embodies such rapid change. In 2015 it changed its US Diet Pepsi formulation replacing aspartame with sucralose and Ace-K (6) but for reasons best known to itself announced in 2016 it was bringing aspartame back while also retaining the reformulated products (7). Meantime so-called natural sweeteners like Stevia aka Truvia are also rapidly increasing in prevalence (4).

'If you can avoid taking in more food, does diet soda still somehow make you gain weight?'

Weight gain without increased food intake is in fact a strikingly consistent observation in many animal model studies on artificial sweeteners (8, 9, 10). How does this happen? Problem with understanding how these artificial sweeteners affect human metabolism and health long-term is each artificial sweetener is different in chemistry, biology and pharmacokinetics (11, 12, 13, 14, see below from 4, 15). Obviously each will induce different metabolic and health effects.

For long, uncertainty dogged epidemiological studies on artificial sweeteners. Do they cause cancer or not? Do they increase risk of diabetes and/or obesity or not? Do they play a role in metabolic syndrome or not? And so on. Given the big bucks riding on ensuring people continued to guzzle at least diet soda even as the tide turned against sodas in general (16), unsurprising really that much of this data is conflicting, mostly due to avoidable study design flaws such as assessing artificial sweetener consumption in conditions far removed from how they're consumed in real life, which is as part of a typical unhealthy 'Western' diet replete in highly processed food and as part of a highly sedentary lifestyle. Few studies included children or elderly or minorities or low income, few examined long-term/chronic/habitual artificial sweetener consumption.

In other words, vast chasm between such studies and real life artificial sweetener consumption patterns. Most importantly, since different artificial sweeteners are used in different processed foods and drinks and since studies rarely address a single artificial sweetener specifically, we essentially don't understand how each artificial sweetener influences metabolism and health long-term (17).

The few studies such as the San Antonio Heart (18) and Longitudinal Study of Aging (19) that examined elderly and minorities long-term (7 to 9 years follow-up) found substantial weight and waist circumference gain with artificial sweetener consumption (in soda, coffee or tea), even without increased food intake, which echoes animal model studies. Increased abdominal fat is of course now a well-known risk factor for cardiovascular disease and type II diabetes.

How to make at least minimal sense of the tower of Babel that is artificial sweetener-related data? Same way as other prickly scientific issues, by looking at conclusions of systematic reviews and Meta-analysis. However, given the entrenched practice of the food and beverage industry funding a massive amount of nutrition research, not meta-analyses by just anyone but rather by those not funded by them. Since Publication bias, i.e., overweening dominance of studies with statistically significant results, is widespread, such reviews and analyses will naturally also be hobbled by the same drawback. However, since they use a set of objective criteria to assess a wide variety of individual studies ranging from cross-sectional to interventional to observational to prospective to randomized, placebo-controlled trials, they're still far more robust and objective than individual studies claiming to find in favor of one or other hypothesis.

• One such review (20) was conducted by federally funded Purdue University researcher Susan E. Swithers. It assessed differences between diet soda non-consumers and consumers among >450000 participants across 14 independent Prospective cohort study, including the San Antonio Heart Study (18), with an average 16-year followup. It concluded that regardless of baseline weight in the two groups, regardless naturally or artificially sweetened, soda consumption increased risk of not just weight gain but also cardiovascular disease, hypertension, metabolic syndrome and type II diabetes (20). Typically, bad news about artificially sweetened stuff is discredited by arguing overweight people tend to choose it in the first place trying to lose weight, i.e., by arguing reverse causality (21). In other words, arguing drinking artificially sweetened stuff doesn't cause weight gain, rather overweight people drink it to try to lose weight. This review (20) found that not to be the case.
• Swithers concluded (20),

‘recent data from humans and rodent models have provided little support for ASB(everages) [artificially sweetened beverages] in promoting weight loss or preventing negative health outcomes such as T2D [type II diabetes], metabolic syndrome and cardiovascular event'

‘current findings suggest that caution about the overall sweetening of the diet is warranted, regardless of whether the sweetener provides energy directly or not’

• No surprise these conclusions were vigorously disputed on the grounds that (22)

'Robust scientific evidence demonstrates benefits of artificial sweeteners’

• In her authoritative rebuttal (23), Swithers points out the American Heart Association (AHA) and American Diabetes Association (ADA) themselves stated in 2012 lack of robust scientific data about artificial sweeteners (24, emphasis mine),

‘paucity of data from well-designed human trials exploring the potential role of (non-nutritive sweeteners) in achieving and maintaining a healthy body weight and minimizing cardiometabolic risk factors.’

• In other words, these products have been unleashed indiscriminately on society, making their way into thousands upon thousands of food and drinks that billions consume and yet we apparently don't know enough to conclude if they're beneficial or not. Sounds like a recipe for a slow motion disaster, which the modern-day global obesity epidemic indeed is, with both sugars and artificial sweeteners obviously playing leading roles.
• Another systematic review of 18 studies by US NIH researchers found association between consumption of artificial sweetened beverages and weight gain in children and teens (25).

Future artificial sweetener research will likely coalesce around at least 3 aspects:

1) How artificial sweeteners influence Gut flora composition and metabolism.

2) How they drive behavioral & metabolic compensation.

3) Biomarkers to identify those at highest risk of sugar/replacer-induced weight gain and/or metabolic disruption.

1) Artificial sweetener effect on Gut flora composition and metabolism.

Since most artificial sweetener studies focus on their effect on body weight, important aspects about their metabolism remain under-studied. This is because they were for long considered inert, passing through the GI tract, untouched, unused, little perturbed and little perturbing. Turns out that's not the case at all (26).

• In a mouse model study (27), maximal daily accepted doses of saccharin, sucralose and aspartame in their drinking water for five weeks induced mouse gut microbiota changes and Impaired glucose tolerance. How this happens is still not clear, especially since aspartame is fully digested to its constituent amino acids in the small intestine unlike saccharin and sucralose. Study found similar results in human volunteers as well. Since most of its experiments involved saccharin, this study's major caveat is limited relevance for diet sodas, which mostly contain aspartame. Obviously similar, larger study needs to examine aspartame effect separately.
• In a rat model study (28), aspartame exposure led to gut microbiota changes and elevated fasting glucose and reduced insulin-stimulated glucose consumption.

Caveat common to all fecal microbiota studies, not just this one: Fecal samples mostly represent distal colon microbiota. Different parts of the GI tract obviously harbor different microbial populations (29). This is especially pertinent for diet vis-a-vis weight gain since most nutrient digestion and absorption is in the small intestine, whose microbial composition is still rather a black box.

Implications of artificial sweetener-induced gut microbiota change:

• Are such changed microbiota better at nutrient harvesting? Better at driving adipose tissue energy storage?
• These would help explain weight gain even without increased food intake.
• Are they more harmful to gut's long-term health, making it more leaky, Intestinal permeability, triggering systemic inflammation?
• This would help explain the long-term harmful consequences such as metabolic syndrome and attendant increased risk of cardiovascular disease and type II diabetes.

2) Hypothesis: artificial sweeteners drive behavioral & metabolic compensation

Since the 1990s, Purdue University researcher Susan E. Swithers has pioneered animal model studies to explore how artificial sweeteners could uncouple sweet tastes from their metabolic consequences and thus distort ability to predict the latter. In other words, artificial sweeteners may alter how the brain processes reward for sweet taste. Her reviews refer to several such experimental studies (30, 31) by hers and other groups.

3) Biomarkers to identify those at highest risk of sugar/replacer-induced weight gain and/or metabolic disruption

Biomarker are measurable, often quantifiable biological indicators of some condition.

As with anything diet-related, some seem to gain weight no matter what or how much they eat, some don't while most of the rest fall somewhere in between. How to proactively identify those at highest risk of weight gain and/or metabolic disruption from artificial sweeteners? The US Scientific Report of the 2015 Dietary Guidelines Advisory Committee advises (32),

'future experimental studies should examine the relationship between ASSD [artificially sweetened soft drinks] and biomarkers of insulin resistance and other diabetes biomarkers'

Only when we have data from such studies will we be able to delve into genetic markers, specific gut microbiota composition, etc., that differentiate those most at risk from the harmful effects of artificial sweeteners, something we have no clue of at present.

Bibliography

1. Stevens, Haley Curtis. "Diabetes and diet beverage study has serious limitations." The American journal of clinical nutrition 98.1 (2013): 248-249. Diabetes and diet beverage study has serious limitations

2. La Vecchia, Carlo. "Artificially and sugar-sweetened beverages and incident type 2 diabetes." The American journal of clinical nutrition 98.1 (2013): 249-250. Artificially and sugar-sweetened beverages and incident type 2 diabetes

3. Vox, Julia Belluz, August 16, 2016. Why (almost) everything you know about food is wrong

4. Popkin, Barry M., and Corinna Hawkes. "Sweetening of the global diet, particularly beverages: patterns, trends, and policy responses." The Lancet Diabetes & Endocrinology 4.2 (2016): 174-186.

5. Sylvetsky, Allison C., and Kristina I. Rother. "Trends in the consumption of low-calorie sweeteners." Physiology & behavior (2016).

6. The Guardian, Suzi Gage, 28 April, 2015. Diet Pepsi has dropped aspartame in the US, so why not anywhere else?

7. Fortune, John Kell, June 27, 2016. Diet Pepsi with aspartame is making a comeback

8. Abou-Donia, Mohamed B., et al. "Splenda alters gut microflora and increases intestinal p-glycoprotein and cytochrome p-450 in male rats." Journal of Toxicology and Environmental Health, Part A 71.21 (2008): 1415-1429. https://www.researchgate.net/pro...

9. Polyák, Éva, et al. "Effects of artificial sweeteners on body weight, food and drink intake." Acta Physiologica Hungarica 97.4 (2010): 401-407. https://www.researchgate.net/pro...

10. de Matos Feijó, Fernanda, et al. "Saccharin and aspartame, compared with sucrose, induce greater weight gain in adult Wistar rats, at similar total caloric intake levels." Appetite 60 (2013): 203-207. https://www.researchgate.net/pro...

11. Byard, J. L., and L. Golberg. "The metabolism of saccharin in laboratory animals." Food and cosmetics toxicology 11.3 (1973): 391-402.

12. Ranney, R. E., et al. "Comparative metabolism of aspartame in experimental animals and humans." Journal of Toxicology and Environmental Health, Part A Current Issues 2.2 (1976): 441-451.

13. Arnold, D. L., D. Krewski, and I. C. Munro. "Saccharin: a toxicological and historical perspective." Toxicology 27.3 (1983): 179-256.

14. Roberts, A., et al. "Sucralose metabolism and pharmacokinetics in man." Food and chemical toxicology 38 (2000): 31-41.

15. Logue, C., et al. "The potential application of a biomarker approach for the investigation of low-calorie sweetener exposure." Proceedings of the Nutrition Society 75.02 (2016): 216-225.

16. The New York Times, Margot Sanger-Katz, October 2, 2015. The Decline of ‘Big Soda’

17. Wiebe, Natasha, et al. "A systematic review on the effect of sweeteners on glycemic response and clinically relevant outcomes." BMC medicine 9.1 (2011): 1. BMC Medicine

18. Fowler, Sharon P., et al. "Fueling the obesity epidemic? Artificially sweetened beverage use and long‐term weight gain." Obesity 16.8 (2008): 1894-1900. https://www.researchgate.net/pro...

19. Fowler, Sharon PG, Ken Williams, and Helen P. Hazuda. "Diet soda intake is associated with long‐term increases in waist circumference in a biethnic cohort of older adults: The San Antonio longitudinal study of aging." Journal of the American Geriatrics Society 63.4 (2015): 708-715. http://www.nutritiondesseniors.f...

20. Swithers, Susan E. "Artificial sweeteners produce the counterintuitive effect of inducing metabolic derangements." Trends in Endocrinology & Metabolism 24.9 (2013): 431-441. http://citeseerx.ist.psu.edu/vie...

21. Drewnowski, A., and C. D. Rehm. "The use of low-calorie sweeteners is associated with self-reported prior intent to lose weight in a representative sample of US adults." Nutrition & diabetes 6.3 (2016): e202. http://www.nature.com/nutd/journ...

22. Johnston, C. A., and J. P. Foreyt. "Robust scientific evidence demonstrates benefits of artificial sweeteners." Trends in endocrinology and metabolism: TEM 25.1 (2014): 1.

23. Swithers, Susan E. "A paucity of data, not robust scientific evidence: a response to Johnston and Foreyt." Trends in Endocrinology & Metabolism 25.1 (2014): 2-4.

24. Gardner, Christopher, et al. "Nonnutritive sweeteners: current use and health perspectives a scientific statement from the American heart association and the American diabetes association." Diabetes care 35.8 (2012): 1798-1808. http://care.diabetesjournals.org...

25. Brown, Rebecca J., Mary Ann De Banate, and Kristina I. Rother. "Artificial sweeteners: a systematic review of metabolic effects in youth." International Journal of Pediatric Obesity 5.4 (2010): 305–312. http://seriecientifica.org/sites...

26. Nettleton, Jodi E., Raylene A. Reimer, and Jane Shearer. "Reshaping the gut microbiota: Impact of low calorie sweeteners and the link to insulin resistance?." Physiology & behavior (2016).

27. Suez, Jotham, et al. "Artificial sweeteners induce glucose intolerance by altering the gut microbiota." Nature 514.7521 (2014): 181-186. https://www.researchgate.net/pro...

28. Palmnäs, Marie SA, et al. "Low-dose aspartame consumption differentially affects gut microbiota-host metabolic interactions in the diet-induced obese rat." PLoS One 9.10 (2014): e109841. http://journals.plos.org/plosone...

29. Lichtman, Joshua S., et al. "The effect of microbial colonization on the host proteome varies by gastrointestinal location." The ISME journal (2015).

30. Swithers, Susan E. "Artificial sweeteners are not the answer to childhood obesity." Appetite 93 (2015): 85-90. http://www1.appstate.edu/~kms/cl...

31. Swithers, Susan E. "Not-so-healthy sugar substitutes?." Current opinion in behavioral sciences 9 (2016): 106-110. Not-so-healthy sugar substitutes?

32. https://health.gov/dietaryguidel...

https://www.quora.com/Is-Diet-Coke-or-other-diet-sodas-good-or-bad-for-dieting-and-weight-loss-Does-diet-soda-cause-people-to-gain-weight-If-so-why/answer/Tirumalai-Kamala