Africa Swap Diet Study Flashcards
Colon cancer risk in African Americans
Colorectal cancer disproportionately affects the Black community, and they are more likely to die from it than any other group
6 components of the standard American diet
- meat-based
- high-calorie
- high-fat
- high-sodium
- low-fibre
- high in sugar
How are meat and colon cancer connected?
Colon cancer is more common among people who eat red and processed meat
Red meat
Unprocessed mammalian muscle meat (beef, veal, pork, lamb, horse, and goat)
Processed meat
Bacon, ham, sausage, and hot dogs preserved by smoking, curing, salting, or adding chemical preservatives such as nitrates and nitrites
What chemicals made in meat processing that is associated with colon cancer?
Carcinogens such as NOC and PAH, heme iron facilitates production of carcinogenic NOCs, and high-temp cooking can produce carcinogenic chemicals (HAA and PAHs)
Soluble dietary fibre
Fibre that dissolves in water; creates a thick gel that slows nutrient absorption, prevent blood spikes and insulin levels, traps dietary fat and bile, and helps feed gut good bacteria
Insoluble dietary fibre
Fibre that does NOT dissolve in water; increases transit time, adds bulk to stool, prevent constipation/hemorrhoids/diverticulitis, and helps feed gut good bacteria
Gut microbiota and western diet
Low gut microbiota diversity is associated with the Western diet
How is colon health in rural Africans?
Rural africans eating a traditional diet have lower prevalence of colon cancer, lower colonic epithelial proliferation rates, and fewer premalignant colonic lesions (polyps)
4 components of the Traditional African diet
- Minimally processed
- High in fibre and starchy carbohydrates
- Low in animal protein (small portions of meat and few eggs)
- Low dairy intake (often fermented)
What was the health of the americans at the start of the swap?
Almost half had polyps, significantly higher mucosal epithelial proliferation, and higher gut inflammation
What was the health of the africans at the start of the swap?
No polyps, lower mucosal epithelial proliferation, and lower gut inflammation
What foods made up the rural South africans diet?
- stiff maize porridge with salt
- seasonal vegetables
- chicken, goats, and few cattle (scarce and generally used as flavouring)
- Eggs, when available
How were the rural south african diet cooked?
Generally boiled, not fried, and cooked in cast iron pots on open wood fires
What is the macro composition of the African American diet?
47% carbs, 35% fat, 15% protein (75% animal), and 14g/day fibre
What is the macro composition of the Rural South African diet?
72% carbs, 16% fat, 11% protein (34% animal), and 66g/day fibre
What are the Canadian daily fibre recommendations?
25g for women, and 38g for men; most are only getting half the recommendations
What was the health of the americans at the end of the swap?
Significantly less colon inflammation, and dramatic drop in multiple risk factors for colon cancer (less cell division)
What was the health of the africans at the end of the swap?
Cancer risk markers increased dramatically, and there was an increased division of colon cells
How did the swap affect the gut microbiome?
African diet increases butyrate production by 250%, a byproduct of fibre metabolism. American diet cut butyrate production in half
What health implications (3) are found from the swap study?
- People can substantially lower risk of colon cancer with more fibre and less red meat
- Risk markers for colon cancer can rapidly switch
- Nutrition transition of the African diet coupled with obesity may lead to the emergence of colon cancer as a major health issue in Africa
