Episode 30: Pimp your gut - The unethical study that blew our mind, Supersize Me and the impact of ultra-processed food

OnCore Nutrition - Two Peas in a Podcast

Tim Spector experiment

https://theconversation.com/your-gut-bacteria-dont-like-junk-food-even-if-you-do-41564

Tim Spector, professor of genetic epidemiology at King’s College London, enlisted his son Tom, a genetics student at University, to undergo an experiment where he lived on McDonalds food for ten days.

Supersize me

• Spurlock ate at McDonald's three times per day - used himself as a guinea pig (n=1) for 30 days.
• Before starting the experiment he was assessed by doctors who confirmed he was in excellent health.
• He did minimal exercise and limited his steps to 5,000 per day to mimic the lifestyle of many Americans who don’t move much and eat fast food regularly.
• Average of 20.9MJ (5,000 kcal) (the equivalent of 9.26 Big Macs) per day during the experiment.
• 2.5 x the recommended caloric intake of average sized male
• gained 11.1kg (24 lb) - 13% increase in weight
• Increased his cholesterol
• Heart palpitations experienced
• Mood swings, sexual dysfunction, lethargy, fat accumulation in his liver.
• It took him 14 months to lose all the weight gained

Ultraprocessed Food

Minimally processed	Lightly processed	Heavily processed	Ultra-processed
pre-cut and peeled pumpkin, potatoes and other veges, bagged salad leaves, bagged spinach, sliced vegetables, and unsalted, roasted nuts Corn Apple	Canned, dried or frozen such as dried fruit, canned legumes/fish, cheese, pasta, frozen veg, pasteurized milk / yoghurt. Recognisable ingredients Make foods available out of season. Canned corn Tinned apples	Food not in its original form or not naturally occurring, eg cereals, muesli bars, deli meats, oils, sugar and flours. Tortilla chips Apple juice	Considered ‘junk food’ eg chips biscuits, chocolates, sweets, nuggets, energy bars, and carbonated and sugared sweet drinks. Doritos Apple pie

Other things that might be damaging your gut health

Smoking

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3597605/

Artificial and naturally intense sweeteners

Saccharin, sucralose, stevia extracts shift the populations of gut microbiota.

Several polyols (fermentable carbohydrates), including isomalt and maltitol, may increase bifidobacteria numbers in healthy subjects, as these polyols may have prebiotic actions.

Large scale human studies are needed

https://academic.oup.com/advances/article/10/suppl_1/S31/5307224

We also know that in animal studies, when exposed to the artificial sweeteners, this saw a reduction in beneficial bacteria in the gut

https://www.ncbi.nlm.nih.gov/pubmed/25231862

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5464538/

They can also give us a preference for a sweeter palate, meaning we crave or feel like sweeter foods..

Exercise (lack of)

• Recent studies suggest that physical activity may also alter the gut bacteria, improving gut health.
• Higher fitness levels have been associated with a greater abundance of butyrate, a short-chain fatty acid that's produced by fermentation of CHO’s in the lower GI tract, helps to keep the lining of our gut healthy and is also important for overall health.
• One study found that professional rugby players had a more diverse gut flora and twice the number of bacterial families, compared to the control groups matched for body size, age and gender

https://www.ncbi.nlm.nih.gov/pubmed/25021423

https://www.hindawi.com/journals/omcl/2017/3831972/

https://www.ncbi.nlm.nih.gov/pubmed/25825908

https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0125889

Alcohol

https://www.ncbi.nlm.nih.gov/pubmed/22552027

• 20 days
• each individual consumed 272 ml of red wine OR de-alcoholized red wine or 100 ml of gin each day
• Gin decreased the number of beneficial gut bacteria,
• Red wine increased the abundance of bacteria known to promote gut health and decreased the number of harmful gut bacteria like Clostridium.
• The beneficial effect of moderate red wine consumption on gut bacteria appears to be due to its polyphenol content.
• Polyphenols are plant compounds that escape digestion and are broken down by gut bacteria. They may also help reduce blood pressure and improve cholesterol

What to focus on

Prebiotic Fibre

• Chicory Root
• Jerusalem artichoke
• Garlic
• Onion
• Leek
• Asparagus
• Less ripe bananas
• Barley
• Oats
• Apples
• Flaxseeds
• Edamame