A combination of two drugs used to treat hay fever and psychosis cooled down the core body temperature of mice and monkeys, reducing brain damage after a stroke. These medications have also undergone preliminary testing in people, and will now be evaluated in a follow-up clinical trial.

Researchers have spent decades investigating ways to chill people鈥檚 brains after they have a stroke to try to limit the damage. The idea is to freeze brain cells in a hibernation-like state so they don鈥檛 need as much oxygen and glucose when a stroke cuts off their blood supply. If brain cells can be kept alive until blood flow is restored, for example, by removing a clot, a patient may be spared from extensive brain damage and related speech and movement problems.

Unfortunately, the physical cooling strategies that have been looked at so far 鈥� including cooling blankets, ice packs and helmets聽鈥� haven鈥檛 worked well. This is because they cause intense discomfort and uncontrollable shivering, says at the University of Newcastle in Australia, who wasn鈥檛 involved in the study.

Shivering is one method the body uses to 鈥渇ight the induction of hypothermia鈥�, making it hard to get body temperature down low enough, she says. 鈥淚t鈥檚 great to see different cooling therapies being tested out for stroke because we know that physical cooling is just not feasible,鈥� says Coupland.

Shuaili Xu at Capital Medical University in Beijing, China, and his colleagues administered the two drugs, promethazine and chlorpromazine, which have been known to reduce body temperature , to mice and rhesus monkeys following induced strokes.

In both animals, the drug combination led to drops in core body temperature, suppressed glucose metabolism in cells and lessened the amount of brain damage caused by the stroke. The reduced brain damage also meant the treated monkeys displayed better use of their limbs.

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Next, the team conducted a clinical trial involving 32 people who had just had a stroke. Upon hospital admission, the subjects were given the promethazine and chlorpromazine combination or a placebo, in addition to standard clot-removal therapy.

The promethazine and chlorpromazine treatment only reduced the patients鈥� body temperature by 0.3掳C (about 0.5掳F) and did not reduce stroke damage. However, Xu thinks this is because the infusions were done over 12 hours, which was too slow to bring down core body temperature by a meaningful amount. 鈥淚t might have led to a low blood drug concentration per unit of time,鈥� he says.

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His team is now launching another trial to see whether faster infusions over an hour produce stronger cooling effects and therapeutic benefits. 鈥淭he fact that they鈥檝e proven that it鈥檚 safe and these drugs are already used in humans for other indications means I think that it鈥檚 reasonable to proceed with further clinical trials,鈥� says Coupland.

Promethazine and chlorpromazine are known to be relatively safe because they have been used for decades. Promethazine is a sedating antihistamine that can ease hay fever and assist sleep, while chlorpromazine is an antipsychotic drug used in the management of schizophrenia and bipolar disorder. They both act on the central nervous system to reduce core body temperature, without translating into shivering or subjective feelings of coldness.

As the temperature drops in Australia, I鈥檝e been seeing recipes on social media for 鈥済olden milk鈥�, a mix of turmeric, other spices and honey in warm milk. In addition to being delicious, it is meant to have medicinal qualities, thanks to a compound in turmeric called curcumin, which gives it its distinct yellow colour. Curcumin is said to have anti-inflammatory properties that are protective against cancer, arthritis, hay fever, Alzheimer鈥檚 disease, menopause symptoms and many other ailments. But is this based on solid evidence?

Turmeric has been used in South Asian cooking and medicine for thousands of years, but has been exalted as a 鈥渟uperfood鈥� in the West over the past couple of decades. This is largely thanks to the research of , a biochemist formerly at the聽University of Texas MD Anderson Cancer Center. Starting in the early 2000s, he published over 100 papers showing that curcumin reduces inflammation and kills 鈥溾�� of tumour cells. This sparked the popularity of the turmeric latte and curcumin supplements, and inspired a bevy of other studies. US health agencies have spent more than on curcumin research since 1990, with a large uptick following Aggarwal鈥檚 early work.

The idea that a tasty, vibrant-coloured spice rooted in traditional Ayurvedic medicine might be a modern medical panacea has appeal. But a large question mark now hangs over the validity of Aggarwal鈥檚 research findings. In 2012, the Office of Research Integrity at the US Department of 91色情片 and Human Services notified MD Anderson Cancer Center about allegations by academic whistleblowers of potentially fraudulent results in (although that does not mean that the results are in fact fraudulent). Aggarwal left the cancer centre after an internal investigation and from scientific journals based on concerns about the authenticity of the results. Aggarwal鈥檚 papers, of which there are several hundred, are still regularly cited. New Scientist was unable to reach him for comment.

Personally, I find it surprising that curcumin has managed to attract so much research attention because a quick look at its chemistry tells you it is unlikely to be much good as a drug. Years ago, when I did a PhD in cancer drug development, one of my lab colleagues experimented with curcumin, but found it almost impossible to work with because of its poor solubility and tendency to degrade. A 2017 in the Journal of Medicinal Chemistry, led by at the University of Minnesota, concluded that 鈥渃urcumin is an unstable, reactive, nonbioavailable compound and, therefore, a highly improbable lead鈥� for therapeutic use.

Because very little curcumin dissolves in water, it isn鈥檛 easily absorbed into the blood following ingestion. Instead, most of it stays in the gut and is excreted in faeces. A study published by Dutch researchers last year found that who took curcumin supplements, even high doses of 鈥渆nhanced鈥� formulations meant to boost absorption with piperidine from black pepper or nanoparticle delivery systems. The concentrations detected in the volunteers鈥� blood were more than 100 times lower than those that have shown activity against cancer cells in a dish.

This probably explains why curcumin has failed to show convincing benefits in any rigorous clinical trials of people with , or other conditions. According to Nelson and her colleagues, curcumin is 鈥渁 missile that continually blows up on the launch pad, never reaching the atmosphere or its intended target(s).鈥�

Too much of a good thing

Concerns have also been raised about the safety of turmeric and curcumin supplements. Turmeric is safe to eat in curries and other meals because small amounts are mixed with other ingredients. Moreover, only around 5 per cent of the dry weight of turmeric is curcumin. But supplements containing concentrated curcumin, especially enhanced formulations, are digested differently and can cause liver problems in some individuals. According to the US聽National Institute of Diabetes and Digestive and Kidney Diseases, 鈥渢urmeric appears to have become the in the United States鈥�, with most cases 鈥渁ttributed to highly bioavailable forms of curcumin鈥� like the enhanced formulations the Dutch researchers studied.

Symptoms of these liver injuries include yellowing of the skin, dark urine and nausea. They usually resolve once a person stops taking the supplement, but a of liver failure.

Another concern is that turmeric products are sometimes adulterated with harmful substances. In the US, for instance, more than a dozen brands of ground turmeric spice were voluntarily recalled between 2011 and 2016 after they were , which was added to enhance the spice鈥檚 yellow colour. Some children who regularly ate food spiced with these products were found to have . In Norway and Sweden, meanwhile, a turmeric supplement that caused liver problems and some deaths was found to be .

I had a go at brewing up some golden milk, hoping the turmeric in my cupboard was lead-free, and can confirm that it is deeply comforting to the soul, if nothing else. I think I will make it a winter staple, but with the recognition that its magic lies in turmeric鈥檚 unique flavour, rather than in any miracle health benefits. Aggarwal and his colleagues once in the journal of the American Association of Pharmaceutical Scientists that curcumin鈥檚 efficacy may seem 鈥渢oo good to be true鈥�.聽He was certainly right about that.