Following the NHS’s advice to eat fish twice a week could make it more prone to the deadliest type of skin cancer, research has suggested today.
The scientists analyzed the diagnostic rates of melanoma among adults who ate the equivalent of 300 g of any type of fish each week, including battered cod. They were compared to participants who consumed much less. Some didn’t even eat any.
The results showed that people who followed official advice, who say a healthy diet includes at least two servings of fish a week, were up to one-fifth more likely to get cancer.
U.S. academics said this could be due to contaminants that cause cancer in fish. But other independent experts said fish is still a key part of a healthy diet and should not be left out.
Meanwhile, a separate study in the United States found that men who consume more than 430 g of milk a day, the equivalent of two cups of milk, are 25% more likely to get prostate cancer than those who have it. less than 20 g.
The British are advised to eat three servings of dairy a day, one of which is a glass of semi-skimmed milk, a pot of yoghurt or a 30 g piece of cheese.
Researchers said hormones naturally present in milk may be to blame.
Men with a family history of the disease were encouraged to “be careful” to drink even “moderate levels” of milk until the findings are clear. And they said they should consider switching to soy, oatmeal or cashew alternatives in the meantime.
The NHS recommends that people eat at least two servings of fish a week, including one of fatty fish, with a serving that weighs about 140 g. But now U.S. researchers have warned that people who eat this amount may be one-fifth more likely to develop malignant melanoma, compared to those who eat 22 g a week.
How much fish should we eat?
A healthy, balanced diet should include at least two servings of fish a week, including one serving of fatty fish.
Most people don’t eat as much. One serving is about 140 g.
However, for certain types of fish, there are recommendations on the maximum amount you should eat.
The British are told to eat at least one serving (about 140 g when cooked) of fatty fish a week.
However, girls, women who plan to have a child, and pregnant women should not eat more than two servings of fatty fish a week.
This is because fish contaminants can affect the future development of babies in the womb.
The British are also being asked to avoid eating too much sea bream, sea bass, turbot, halibut, rock salmon and crabs, as they also contain contaminants.
Source: NHS
For the first study, researchers at Brown University studied data from 491,367 adults who provided dietary data in the mid-1990s. They were sixty years old when the study began.
Participants were asked about how often they ate fried and uncooked fish and tuna during the previous year, as well as the size of their portions.
Scholars then tracked new cases of melanoma among participants over the age of 15, using data from cancer records.
The results, published in Cancer Causes & Control, showed that 5,034 people developed malignant melanoma during the study period. Almost all stage 1 cancer patients survive, but the rate drops to just three out of 10 for those trapped in stage four.
Some 3,284 cells developed abnormal cells in the outer layer of the skin, known as stage 0 melanoma or in situ melanoma (sometimes also known as precancerous).
The team found that people with a typical daily fish intake of 42.8 g, equivalent to about 300 g per week, were 22% more likely to develop malignant melanoma than those with a daily intake of only 3.2 g. g.
Those who ate more fish also had a 28% higher risk of melanoma in phase 0.
But the results did not apply to eating fried fish, the study showed. The risk was only observed for adults eating melody or uncooked fish, which the NHS says are healthier options.
Current health service advice states that the British should eat at least two servings of fish a week, including one of fatty fish.
The study’s author and dermatologist, Dr. Eunyoung Cho, said the team’s findings “have identified an association that requires further research.”
He said: “We hope that our findings could be attributed to fish contaminants such as polychlorinated biphenyls, dioxins, arsenic and mercury.
“Previous research has found that higher fish intake is associated with higher levels of these contaminants within the body and have identified associations between these contaminants and an increased risk of skin cancer.
“However, we note that our study did not investigate the concentrations of these contaminants in the bodies of the participants, and therefore further research is needed to confirm this relationship.”
The researchers looked at factors that could influence the outcome, such as weight, diet, whether they smoked or drank alcohol, and their family history of cancer.
The team also recorded average levels of UV radiation in local areas of volunteers to account for sun exposure, a known risk factor for skin cancer.
But they did not take into account other key melanoma risk factors, such as the number of moles, hair color, a history of severe sunburn, and whether people sunbathe or use sunscreen.
In addition, the average daily fish intake was calculated at the beginning of the study and may not represent how much people eat over their lifetime.
Dr Michael Jones of the London Cancer Research Institute did not take part in the study, but said the results were “statistically significant and therefore unlikely by chance”.
But he noted that people who eat more fried and refined fish may have other lifestyle habits that increase the risk of melanoma. More research is needed to confirm the findings, Dr. Jones said.
He added: “An overall healthy balanced diet should include fish and the results of this study do not change that recommendation.”
Dr. Duane Mellor, a tenured professor at Aston Medical School, who did not participate in the study, said that if fish contaminants are to blame for the increased risk of skin cancer, it would also increase rates of skin cancer. ‘other cancers.
He said the study does not identify a clear way how eating fish could increase the risk of melanoma and eating two servings of fish a week is “part of a healthy diet.”
Health experts at Loma Linda University in California have warned today that men who consume 430 g of dairy a day are more likely to be diagnosed with prostate cancer than those who are only 20 g, only half a cup of milk. per week.
How much dairy should we eat?
Milk and dairy products provide calcium for healthy bones and teeth.
The best foods to provide calcium are yogurt, milk and cheese.
The British are told to aim for two to three servings each day.
A serving is a small piece of cheese the size of a matchbox (about 30 g), a 150 g yogurt pot, and a glass of milk.
Milk and dairy products typically provide almost a third of the recommended calcium intake.
But the nutrition that dairy products provide goes beyond calcium.
A glass of semi-skimmed milk provides protein, potassium and three-quarters of the daily requirement of vitamin B12.
Meanwhile, Loma Linda University Health experts in California also warned today that men who consume 430 g of dairy a day are more likely to be diagnosed with prostate cancer than those who are only 20 g, only half a cup of milk per day. week.
Researchers studied the dairy intake of more than 28,000 men in the U.S., all of whom were initially cancer-free. Information about their diet was gathered through regular questionnaires and phone calls.
The team used cancer records to determine which patients had developed prostate cancer eight years later. Some 1,254 people had been diagnosed.
About 52,000 men in the UK and 270,000 in the US are diagnosed with prostate cancer each year. About 80% of men for 10 years after confirmation of their cancer.
The findings, published in the American Journal of Clinical Nutrition, show that those who weighed 430 g a day were a quarter more at risk than those who weighed only 20 g a day.
And men who consumed 430 g a day were 62% more likely to develop prostate cancer than those who did not have dairy in their diet.
However, the consumption of cheese and milk was not related to prostate cancer, the team said.
The Dietitians Association of the United Kingdom advises the British to consume three servings of dairy a day, one serving is equivalent to a glass of semi-skimmed milk, a pot of 150 g of natural yoghurt or 30 g of cheese.
No link was found between non-dairy sources of calcium, such as nuts, seeds, vegetables, legumes, fortified fruits and grains, and prostate cancer.
This suggests that substances other than calcium in dairy products are to blame, they said.
And there was a “minimal” variation in prostate cancer risk among those who had whole milk compared to people who opted for low-fat or fat-free options.
The researchers found no correlation between increased dairy intake and an equal increased risk of prostate cancer.
Dr. Gary Fraser, study leader and expert in internal medicine and cardiovascular disease at the university, said the risk no longer increases among people who already consume 150 g of dairy a day, about two-thirds of a cup of milk.
He said, “It’s almost as if some biological or biochemical pathway is saturated with about two-thirds of a cup of milk a day.”
Dr. Fraser said the findings could suggest that dairy foods are “causally related to the risk of prostate cancer.”
He said this could be due to the sex hormone content of the milk. About three-quarters of the milk comes from cows that are pregnant, and prostate cancer is a “hormone-responsive cancer.”
Previous studies have found that consuming dairy increases the levels of a hormone in the blood called insulin-1-like growth factor, which is believed to increase the risk of developing some cancers.
Dr. Fraser said he would encourage men with a family history of prostate cancer, or those with other risk factors, to “be careful” to drink even “moderate levels” of milk until the findings are clarified.
“If you think you have a higher than average risk, …