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More on eating green foods safely



by Professor Panduka Karunanayake

I was interested in two recent articles in The Island on the issue of the safety of green vegetables in our diet. The first was ‘Throw more light on green foods’ by Mr Gamini Pieris (September 26) and the second was a response to the first, ‘Are murunga and kathurumurunga leaves toxic?’ by the eminent scientist Dr Parakrama Waidyarathna (October 5).

Sri Lanka is a country with a rich biodiversity of flora. Naturally therefore, fruits and vegetables, including green vegetables, constitute a significant proportion of our average diet – as they should. They contain many vitamins, minerals and trace elements, as well as fibre and sometimes even protein. Because of their abundance and low cost (in most instances), they are a gift of nature especially to our rural folk. There is no question that their use should be generally encouraged.


But these two articles specifically addressed their toxicity, which is a rare but important issue. As Dr Waidyarathna pointed out, plants do also contain toxic substances. Scientists such as he should help us all decide on the safe use of plant foods, not only with regard to choosing them but also with regard to aspects such as their growth conditions, harvesting practices, storage, preparation and preservation, all of which may have a bearing on increasing or decreasing their toxicities. In this regard, we should be thankful to Dr Waidyarathna for his kind response of October 5.

Regarding toxicity, there is a lot that these scientists know already, but there may also be a lot that is yet to be scientifically elucidated. The usual practice, especially among medical doctors, in the face of any uncertainties is to adopt the precautionary principle: avoid any possible dangers if there is a choice.Plants can be toxic in one of two main ways: the first is dose-dependent (as stated so elegantly by Paracelsus) and the other is not.

Idiosyncratic reactions

The non-dose-dependent toxicity occurs due to an idiosyncrasy of the person, who cannot then tolerate even a small, so-called ‘safe’, dose of a substance. A good example of this is how the plant kuppamenia can affect persons with a genetic predisposition called G6PD deficiency by causing a dangerous destruction of their red blood cells (haemolysis).

Interestingly, G6PD deficiency is commoner in human populations that have co-evolved with malaria, because it confers a survival advantage to recover from malaria. As a result, kuppamenia is likely to be more troublesome in malaria-endemic areas, because G6PD deficiency may be commoner there. Indeed, it is common knowledge among the traditional folk in Rajarata – which used to be highly endemic for malaria for millennia – that kuppamenia is a ‘harmful’ plant.

Dose-dependent reactions

The dose-dependent form of toxicity is generally considered to occur if any person happens to take a larger-than-usual dose of the substance. But here, there is a trick. We are usually accustomed to thinking of a high dose as something taken in a large quantity in one meal. But there can be another situation. A person may take a small dose repeatedly, and while one intake may not be toxic, if it is taken in repeatedly and continuously in even a small dose, it could gradually accumulate in the body and reach dangerously high levels. That too can lead to harm. In other words, the ‘dose’ that Paracelsus referred to may have been the dose in one intake, but we should actually consider the dose in whatever form of intake that creates a dangerous plasma level – be it as one intake or as several repeated, frequent intakes. This latter situation occurs when there is a problem with the elimination of the substance from the body.

Problems with elimination

When the body takes such substances, it usually gets rid of them from the body (which is technically called ‘elimination’) through either the liver (by enzymatic metabolism) or the kidneys (by excretion in urine). The rate at which this happens is called ‘the elimination half-life’: this is the time (in hours or days) it takes to eliminate the substance to such an extent that the plasma concentration is reduced to half of the initial level.

Theoretically, if the elimination half-life is >24 hours and the substance is taken in every day, the elimination can never be complete and accumulation can occur – with the possiblity of reaching a toxic concentration. An example of this is how the repeated ingestion of aristocholic acid-containing plants (as a ‘natural slimming medicine’) led to kidney failure and cancer.If several similar plant substances share the same elimination mechanism (such as the metabolising enzyme), they can decrease each other’s elimination (by competition) and cause a lengthening of the elimination half-life – leading to further risk of accumulation.

There are also substances (such as food constituents and medications) that specifically inhibit such elimination mechanisms (by inhibiting the metabolising enzyme), and if these are taken in simultaneously too, accumulation can occur.

Naturally, if the elimination is faulty for some other reason, accumulation occurs more readily and rapidly. An example of this is how eating kamaranga (which is promoted by ‘natural therapists’ for ‘reducing cholesterol’, ‘preventing cancer’, ‘promoting digestion’, ‘regulating blood pressure’ and ‘producing weight loss’ – none of which has a scientific basis) produced toxicity (confusion, uncontrollable seizures and even death) in patients with impaired kidney function.

Precautionary principle

These are of course theoretical considerations that can be important only in occasional or rare situations, but the precautionary principle is important to avoid such calamities. If we did that, the simple advice is to eat a variety of plant foods every day, and avoid eating the same the plant food frequently. When a substance is taken in only infrequently, it cannot accumulate. In a country such as ours with its abundance of varieties of plant foods, this should not pose any problem and would even be desirable. I wonder if it is this type of reasoning and the adoption of the precautionary principle that led the physician mentioned by Mr Pieris to give that advice. That would not be an advice specific to either murunga or kathurumurunga – it would apply across the board to all green vegetables.

Interestingly, a natural phenomenon that highlights the possible dangers of plant foods is the occurrence of morning sickness in early pregnancy. Anthropologists generally agree that the evolutionary advantage of morning sickness is that it ensures that pregnant mothers reduce their food intake during early pregnancy, so that the fetus is not exposed to any toxins in food during its crucial period of organ formation (organogenesis). That reduces malformation of organs, and gives our species the evolutionary advantage. Indeed, I think that the precautionary principle with regard to green foods should be adhered to even more seriously during early pregnancy.

It is also important to keep in mind that we should not promote any particular type of green food for scientifically unsubstantiated benefits. It is generally that type of promotion that leads to the repeated and frequent consumption of one particular plant food. The recent horrors that had resulted – the stories of kamaranga and aristocholic acid nephropathy – should remind us of the dangers of such promotions. Unfortunately, with the richer biodiversity of our flora comes also a greater abundance of tall stories about their ‘benefits’!

(The writer is a professor in clinical medicine in the University of Colombo.)

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Science vs religion – II



Of course, there are many shortcomings and limitations of the scientific method. Scientific knowledge alone is certainly not enough to make humans attain their full potential. The human values we live by, and questions of meaning and purpose, morality or ethics. are not amenable to hypotheses, modelling, and mathematical equations. They rely on methods that are interpretive, speculative, and philosophical.


(The first part of this article reproduced from our Asia News Network partner in India, The Statesman, appeared on 25 Nov.)

“The known is finite, the unknown infinite”, the British biologist Thomas Huxley wrote in 1887, “Intellectually we stand on an islet in the midst of an illimitable ocean of inexplicability. Our business in every generation is to reclaim a little more land.”

Before the last century, the vast unknown territory of inexplicability was ruled by religion.But the last century has seen a tremendous explosion of scientific knowledge, and ever since, science has been reclaiming more and more territory from religion so that scholars started predicting a diminishing relevance and eventual disappearance of religion from human society.

While it is true that religion’s stranglehold has been remarkably weakened in most countries during the last half-century, except in the diehard Islamic states which stubbornly refuse to reform Islam, the resurgence of religion in our contemporary socio-political life negates the prediction of religion’s demise.

There is too much religion on the streets now that is increasingly intruding unto our lives. It is not the spirituality that Sagan had talked about, it is religion in its crudest original form – bloodthirsty, demanding total and unquestioning allegiance from its followers who would not shy away from spilling the blood of non-believers. While science continues to conquer ever newer frontiers and invents technologies that are revolutionising our society, a full transition to a scientific society is not possible without the complete displacement of religion.

From medicine to biotech, from electronics to telecommunication, from AI to nanoscience, the progress of science during the last 50 years has completely transformed the way we organize society, conduct business, and connect with people for ideation.

The paradox is that while we are exploring the frontiers of science and technology driven by limitless human yearning and thirst for knowledge, we are also reinforcing the prejudices, bigotry, and intolerance of contrary ideas and beliefs in our social and public life with renewed vigour and pride. Of course, there are many shortcomings and limitations of the scientific method.Scientific knowledge alone is certainly not enough to make humans attain their full potential. The German philosopher Edmund Husserl argued against recurrent tendencies of applying the methods of natural science in the research of human affairs, which are essentially outside empirical scientific approaches.

The human values we live by, and questions of meaning and purpose, morality or ethics, etc. are not amenable to hypotheses, modelling, and mathematical equations. They rely on methods that are interpretive, speculative, and philosophical. This is always an epistemological problem in social sciences, and this is where religion is supposed to supplement the techno-scientific worldview of science to understand how Nature works her laws in the universe and in human society.

But Nature also includes her children and us humans, and her well-being depends on their activities. No one knows that better than us, especially at this juncture of time when the world is precariously poised between sustainability and irreversible devastation from uncontrolled human greed.

Religion was supposed to impart and promote morality, ethics, love, and compassion among humans to make them understand their symbiotic relationships with nature, with fellow beings, and with animals. Religion was supposed to teach humans to limit their greed, increase empathy towards others, and strike a harmonious balance with nature to make the world a better place for all to live. What it has done and the moral blindness it has promoted instead is for all to see and judge.

Religion today is relentlessly marching to colonize every aspect of our socio-economic and political life with increasing aggressiveness. Suffering has been trivialised by it, the pain has been glorified by it, killing has been sanctified by it and the tattered social fabric that has resulted is being flaunted with egotistical pleasure and pride.

Though it will be unfair to blame religion alone, it has to take a large share of the blame for this sorry state of affairs. It is propelling us energetically to forget our humanity and respect for those who do not share our faith and driving us towards an Orwellian world where intercultural understanding, the richness of culture and diversity, and the ideal of an inclusive and pluralistic society are strongly denounced in favour of a blind pursuance of faith as dictated by its self-proclaimed guardians and their bigoted followers.

The ideal of peace and harmony are receding at the speed of light as religion strives to regain the territory it has lost to science and is countering science with what can best be described as a pseudoscience that is carving out a niche for itself – and a wide one at that.To quote Huxley again, “The question of all questions for humanity is that of the determination of man’s place in nature and his relation to the Cosmos.”

Religion derived sustenance from the concept that humanity was positioned proudly at the centre of God’s magnificent creation, the Earth, around which revolved everything, and humanity – the crowning achievement of God’s creation in his own image, the pinnacle of his divine handiwork, occupied the centre-stage on this earth.Science would shatter the concept, but not before thousands of Giordano Brunos were burned at the stake for holding a contrary view.

In The Structure of Scientific Revolutions (1962), Thomas Kuhn convincingly explained how paradigm shifts take place in the history of science when one dominant worldview is replaced by another. He showed that scientific progress is like Darwinian evolution – a process of selection of one amongst all the competing theories that have the most predictive power puzzle-solving ability, a concept that was later supported by Bas van Fraassen in The Scientific Image (1980).

But each such major paradigm shift has shaken the edifice of religion from which it could never recover. Thus, when the geocentric Ptolemaic worldview was replaced by the Copernican worldview, man lost his centrality in the scheme of things. Till then, heaven was in the sky, hell was underground and God in heaven ruled all three while religion regulated the entry to heaven or hell.

Copernicus banished the earth from the centre of the Universe, and later Hubble displaced the entire Milky way from the centre of the universe, giving us instead an expanding universe of billions of galaxies in which neither is humanity at the centre of creation nor is the earth at the centre of the universe; in fact, the universe itself is one tiny dot in a multiverse of many universes.

Thus, God’s magnificent creation has been relegated to the position of a second-rate planet attached to a third-rate star, discarding religion’s medieval fancies. Today we are humbled by the immensity of the universe and mesmerized by the eternal silence of infinite space.

But for religion, the determination of man’s place in nature and his relation to the cosmos was not a question, it was an irrefutable truth questioning which meant inviting risk. Copernicus wrote De Revolutionibus Orbium Coelesticum on his deathbed in 1543, beyond the morbid reach of the Inquisition.

Galileo and Bruno were not that fortunate. Science established that neither does life enjoy any special privilege – countless worlds exist in deep space devoid of life, and countless species have become extinct in the course of evolution. We may be one someday, and going by our misdeeds on this planet, that day even may not be too far.

Darwin would finally dislodge humanity from the centre of the biological universe, giving it a lowly ancestor that was too humble compared to an almighty God to be a creator of such intelligence as possessed by man. Thankfully, the inquisition was dead, but prejudiced minds that shun logic were not. They are again back at the centre stage in force, flaunting scriptures, dictating how we should conduct ourselves, threatening to push us into a hell of ignominy and violence if we disobey.

Creationism is still being taught in many US public schools, despite the Supreme Court ruling to the contrary. Half the people in the USA still don’t believe in evolution, their share in India is unknown. But here, vigorous attempts are now on somehow bringing God inside the classroom in any guise, be it a hijab, or anything else.

Worship only makes you a slave. A slave forgets his reason, and his purpose for existence, and ultimately becomes an automaton to serve the master – Religion – and obey its commands without thinking.Religion is not the source of spirituality, peace, morality, virtue, and ethics any longer. Its principles may be eternal, but its methods are gross. It has now become the source of violence, hatred, unconcealed greed, corruption, and a road to power.

Instead of breaking barriers, it is building them afresh, destroying the very roots upon which mankind has built civilizations through the millennia. Don’t expect the State to control religion and the street will always celebrate it with ever-ostentatious pomp and splendour. It is therefore for us citizens to shield our children from the corrupting influences of religion. It has no place in the fabric of the mind of civilized men and women, just as God has no place in the fabric of the space-time that science tries to untangle. We don’t need the ancient wisdom of the spirit to guide us, because religion which was supposed to imbibe it has lost its divinity. It is now for science to redeem religion.


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A dreamer’s dream



Last night as usual I watched the local news, leaving aside the World News and the FIFA matches on TV, looking for some encour-aging news about the financial situation in our country. On all TV Channels The daily scenes in Parliament are always the same very chaotic and a waste of time to listen. The arguments in Parliament resembles the Maria Kade fish market between some women, accusing one another in filth.

Rather disappointed I fell asleep. I dreamt I was at the Aragalaya on the Galle Face Green packed with jolly enthusiastic people seemed on holiday-spirit singing and enjoying the music, and some drowning the noise with speeches through loudspeakers. Walking around I noticed there was a bus with a full load of passengers stuck and surrounded by a mob who was trying to topple it.

Finally the bus toppled and they all clapped and cheered not caring for the poor frightened passengers in the bus. One of the mob leaders gave a speeh and then got the bus upright, and tried to start it, but couldn’t. Then they pushed and it wouldn’t start as the tank was empty . The wounded passengers came out crying some wounded with fractures and bleeding. Someone phoned for ambulances but none came. To my horror the Aragalaya then attacked that mob who toppled the bus and in the utter choas I woke up in a cold swept.

Recollecting my dream I wondered whether this dream is similar to what would happen to our country.

D. L. Sirimanne,

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How many people can the Earth sustain?



=On Nov 15 November 2022, we became a world of 8 billion people. 

It’s a milestone we can celebrate, and an occasion to reflect: How can we create a world in which all 8 billion of us can thrive? The growth of our population is a testament to humanity’s achievements, including reductions in poverty and gender inequality, advancements in health care, and expanded access to education. These have resulted in more women surviving childbirth, more children surviving their early years, and longer, healthier lifespans, decade after decade.

Looking beyond the averages, at the populations of countries and regions, the picture is much more nuanced – and quickly takes us beyond the numbers themselves. Stark disparities in life expectancy point to unequal access to health care, opportunities and resources, and unequal burdens of violence, conflict, poverty and ill health.

Birth rates vary from country to country, with some populations still growing fast, others beginning to shrink. But underlying these trends, whichever way they point, is a widespread lack of choice. Discrimination, poverty and crisis – as well as coercive policies that violate the reproductive rights of women and girls – put sexual and reproductive health care and information, including contraception and sex education, out of reach for far too many people.

We face serious challenges as a global community, including the mounting impacts of climate change, ongoing conflicts and forced displacement. To meet them, we need resilient countries and communities. And that means investing in people and making our societies inclusive, so that everyone is afforded a quality of life that allows them to thrive in our changing world.

To build demographic resilience, we need to invest in better infrastructure, education and health care, and ensure access to sexual and reproductive health and rights. We need to systematically remove the barriers – based on gender, race, disability, sexual orientation or migration status – that prevent people from accessing the services and opportunities they need to thrive.

We need to rethink models of economic growth and development that have led to overconsumption and fuelled violence, exploitation, environmental degradation and climate change, and we need to ensure that the poorest countries – which did not create these problems, yet bear the brunt of their impacts – have the resources to build the resilience and well-being of their growing populations.

We need to understand and anticipate demographic trends, so that governments can make informed policies and resource allocations to equip their populations with the right skills, tools and opportunities.

But while demographic trends can help guide the policy choices we make as societies, there are other choices – including if and when to have children – that policy cannot dictate, because they belong to each individual. This right to bodily autonomy underlies the full range of our human rights, forming a foundation for resilient, inclusive and thriving societies that can meet the challenges of our world. When our bodies and futures are our own, we are #8BillionStrong.


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