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Why people who eat home-cooked meals less likely to develop cancer, infertility

By Chukwuma Muanya
24 October 2019   |   3:39 am
A new study suggests that making your own meals protects you from toxic ‘forever chemicals’ linked to reproductive and immunity problems and cancer. Scientists at the Silent Spring Institute found that people who ate home-cooked meals more often had fewer of these chemicals, known as PFAS, in their bodies.


A new study suggests that making your own meals protects you from toxic ‘forever chemicals’ linked to reproductive and immunity problems and cancer.

Scientists at the Silent Spring Institute found that people who ate home-cooked meals more often had fewer of these chemicals, known as PFAS, in their bodies.

These chemicals can be found in many places in our environment, and get into our food – especially certain products’ packaging, such as fast-food wrappers and the bags microwaved popcorn is cooked in.

But cooking at home can cut your exposure to PFAS, helping to protect you against certain cancers and thyroid problems – all while ensuring there are more nutrients packed into every bite you take.

There is no perfect protection against environmental toxins, especially those that never go away, like PFAS.

PFAS – shorthand for per- and polyfluoroalkyl substances – were a revelation when chemists developed them in the 1930s.

The chemicals made possible now-ubiquitous household items like non-stick cookware, and waterproof fabric coatings, as well as incredibly powerful fire-extinguishing foams.

Foams like these have undoubtedly saved many lives.

But animal studies suggest they’ve put virtually all of us in the US at elevated risks of a number of health problems.

Exposure to these chemicals, which do not break down in the environment or body, has been linked to poorer fertility, higher cholesterol, hormonal and immune system disruptions, higher cholesterol and higher risks of cancer.

They are found in many foods, but not in equal prevalence from product to product.

So the chemists at Silent Spring used data on the dining habits and blood levels of PFAS in over 10,000 Americans to work out which eating patterns were best and worst for PFAS exposures.

People who ate out at restaurants of any kind had more frequently had higher levels of PFAS floating around their bodies.

Although they did not analyze the packaging itself, the researchers suspect that the more wrappers and packaging your food touches, the more PFAs sneak into what you eat.

And, as they suspected, popcorn lovers were some of the worst-off. Home cooks, on the other hand, were protected.

The more often people not only ate at home – indulging in taking out – but bought groceries and cooked them themselves, the lower there PFAS expoures were.

“This is the first study to observe a link between different sources of food and PFAS exposures in the US population,” said Dr. Laurel Schaider, a Silent Spring chemist and study co-author.

“Our results suggest the migration of PFAS chemicals from food packaging into the food can be an important source of exposure to these chemicals.”

Also, roasting those carrots as opposed to eating them raw could drastically change your gut bacteria, a new study finds.

In research conducted in both mice and humans, scientists found that eating cooked food not only changed the bacteria in our bodies – collectively known as the microbiome – but whether these microbes’ genes were turned ‘on’ or ‘off’.

Researchers say this is because eating cooked food can boost your gut health while many raw foods contain compounds that kill microorganisms, meaning a lot of our intestinal bacteria are destroyed.

The team, led by the University of California San Francisco, says the findings help us understand which foods leave us with the most beneficial bacteria in our bodies and how our microbiomes evolved as early humans learned how to cook food.

“Our lab and others have studied how different kinds of diet – such as vegetarian versus meat-based diets – impact the microbiome,” said senior author Dr. Peter Turnbaugh, an associate professor of microbiology and immunology at UCSF.

“We were surprised to discover that no one had studied the fundamental question of how cooking itself alters the composition of the microbial ecosystems in our guts.”

For the study, published in the journal Nature Microbiology, the team split mice into four groups.

The rodents were fed one of four diets: raw meat, cooked meat, raw sweet potatoes or cooked sweet potatoes.
Researchers found, to their surprise, that there was no difference in the microbiomes of mice who ate raw meat versus cooked meat.

However, there was a significant difference between the mice who ate raw sweet potatoes and cooked sweet potatoes.

Not only was the bacteria in their bodies different, but also whether certain genes were ‘on’ or ‘off’ and the metabolic products – such as waste – produced by the body.

When the team did the same experiment with an assortment of vegetables – including white potatoes, corn, peas, carrots, and beets – they got the same results.

Researchers say one of the reasons for these changes is that several raw foods contain antimicrobial compounds that damage or kill bacteria in our bodies.

“We were surprised to see that the differences were not only due to changing carbohydrate metabolism but also may be driven by the chemicals found in plants,” Turnbaugh said.

“To me, this really highlights the importance of considering the other components of our diet and how they impact gut bacteria.”

UCSF researchers wanted to see if similar microbiome changes would occur in humans and partnered with a professional chef to prepare raw and cooked menus.

Participants tried each diet for three days in random order and then provided stool samples. The samples revealed that the microbiomes of those who ate a raw diet versus a cooked diet were distinctly different.

Meanwhile, symptoms of inflammatory bowel disease (IBD) can be relieved through diet in the space of a month, a study has found for the first time.

King’s College London scientists tracked patients with Crohn’s disease or ulcerative colitis who were put on a ‘low FODMAP’ diet.

Volunteers were told to restrict certain carbohydrates, which include wheat, fruits high in sugar and various other foods.

More than half of those studied saw a reduction in the severity of their symptoms after four weeks, such as bloating, diarrhoea and abdominal pain.

Despite years of research, scientists have never discovered an effective diet for IBD patients – although some foods may trigger symptoms. These are managed with drugs or surgery.

Even during periods when the disease is in remission, and medication is controlling gut inflammation, symptoms can persist in everyday life.

The King’s College London study offers fresh hope of a safe and cost-effective way of relieving the symptoms suffered by thousands.

Lead researcher Dr. Selina Cox said: “We know that the low FODMAP diet is effective in patients with irritable bowel syndrome (IBS). This is the first randomised, trial showing that it’s effective in reducing common gut symptoms. This improves health-related quality of life in patients with IBD when they are in remission.”

Inflammatory bowel diseases, such as Crohn’s disease and ulcerative colitis, involve chronic inflammation of the digestive tract. Fifty-two patients were used in the study. They all had persistent symptoms of IBD – despite their inflammation is under control with medication.

The participants were divided into two groups, 25 followed a normal diet and 27 adopted a low FODMAP diet.

FODMAPs – fermentable oligosaccharides, disaccharides, monosaccharides, and polyols – are types of carbohydrates found in certain foods.

Typically foods that contain wheat, such as cakes, biscuits, bread, and white pasta, are banned on the restrictive diet.

Dairy products are a no-go, as well as fruits and vegetables containing high fructose, such as apples, bananas, and pears.

Of the group that followed a low FODMAP diet, 52 per cent reported adequate relief of gut symptoms after four weeks. In contrast, just 16 per cent of the ‘normal’ diet group experienced the same benefit, according to the researchers.

According to the paper published in the journal Gastroenterology, the low FODMAP group had a higher quality of life score, too.

The researchers also took stool and blood samples at the beginning and end of the study to assess gut bacteria levels among the volunteers. They found patients on the low FODMAP diet had less of a certain gut bacteria called Bifidobacteria after four weeks.

The scientists said this was concerning because Bifidobacteria can be beneficial for people with IBD by reducing inflammation. But despite the changes, gut inflammation did not appear to increase after the low FODMAP diet, results showed.

And, overall, the gut microbiome diversity and markers of inflammation did not differ significantly between the two groups.

Commenting on the findings, Professor Kevin Whelan from King’s, said: “Indeed, this could represent a safe and cost-effective management option.”

The team at King’s plan to study the long-term effects of a low FODMAP diet and see what happens if FODMAP foods are reintroduced to the diet.

Dr. Cox said: “In clinical practice, the low FODMAP diet is followed by a phase of gradual FODMAP reintroduction.

“It is important to establish what the effects of FODMAP reintroduction are on the gut and whether reintroduction reverses the bacterial changes that were observed during the low FODMAP diet.”