People who have been exposed to high levels of toxins found in some vegetables and fruit may benefit from eating more of the types of vegetables and herbs people who are sensitive to toxins find beneficial.
The latest research from the Harvard School of Public Health and the Harvard-Smithsonian Center for Astrophysics found that a diet rich in red and purple fruits and vegetables was linked to lower levels of a protein found in meat, and a diet with lots of black leafy vegetables was also linked to higher levels of the protein.
Researchers studied 1,500 adults and children aged 8 to 65, including more than a quarter of those who lived in California and New York.
The children and adults were tested for levels of one of seven protein biomarkers known as ALT, or alpha-L-arginine, or beta-L.
The findings appear in the journal PLOS One.
They were based on an analysis of more than 13,000 adults and a small group of children who also lived in New York City.
The results showed that people who ate a diet high in red, purple and black fruits and veggies were significantly less likely to develop ALT and had a lower risk of developing type 2 diabetes than those who ate less red, black and purple foods.
People who ate the most fruits and vegetable were also more likely to have type 2, diabetes and cardiovascular disease.
People on a high-fat, high-sugar diet were also less likely than those on a low-fat diet to develop diabetes, while people on a diet low in fruits and greens were more likely than people on low-sugars diets to develop the disease.
Low-fat diets are low-carbohydrate diets that usually include fruit, vegetables, whole grains, beans, legumes, nuts and seeds.
Low sugar is sugar made from sugar cane or sugar beets.
Low fat is fats made from vegetable oils, palm oil and canola oil.
In addition to the researchers, the findings are from a separate study by the University of Wisconsin-Madison, which found similar results.
A spokesman for the American Academy of Pediatrics said it has no data about the findings.
“We need more research on the effect of red and white, red and green, red versus purple, and black versus white on ALT levels,” said Dr. Robert Schwartz, a spokesman for Pediatrics.
“We need to get a clearer picture of what the evidence says.”
Schwartz said there are a number of other food types that have been linked to an increased risk of type 2 and diabetes, including high-fructose corn syrup and trans fats.
The study also looked at the effects of different foods on ALTs.
People eating the most red, red, green and purple fruit had a significantly lower risk for developing diabetes than people who consumed the least, Schwartz said.
People with a history of heart disease and people who drank two or more sodas had the lowest risk of diabetes.
The researchers are still trying to understand the exact role red and black foods play in type 2 risk, Schwartz added.
There is evidence that foods rich in antioxidants, including red and blue fruits and green and blue vegetables, can help lower blood sugar levels, Schwartz told Reuters Health.
Researchers are also still working to understand what the mechanisms are behind the protective effects of fruits and veg.