Endotoxins such as liposaccharides (LPS) are potent inflammatory antigens and are found in the human gut. (1,2) There is however another potent source of endotoxins coming directly from the food we eat.(1,3,4) Evidenced by significant increases in endotoxin concentrations in as little as 30 minutes after consuming a meal and is emerging as a prime suspect in postprandial inflammation. (1,4)
 
Capable of passing through the gut wall and entering systemic circulation, endotoxins cause substantial increases in chronic inflammatory markers such as NF-kB, IL-6 and TNF-a.(1While mild postprandial inflammation is common, it was shown that minimising dietary intake of endotoxins reduced inflammation and improved cardiometabolic markers.(3,5)
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Which foods contain high levels of endotoxin?

According to Herieka et al (2016), there may be endotoxins in foods generally considered healthy and is highly dependent on food preparation. Pre-packaged and processed foods including minced meat and pre-cut vegetables which are seemingly ‘unspoiled’ and kept refrigerated frequently contain large amounts of endotoxin resulting in chronic inflammation and even endotoxemia.(3)

Some research also suggests certain fats unfavorably alter intestinal permeability, allowing endotoxins from a meal to pass into systemic circulation, however the exact mechanism is still unclear.(1,4,6)
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Given that inflamm-ageing is associated with changes in digestion, metabolism, our microbiome and inflammatory status, we may need to amend the current anti-inflammatory diets to include ‘fresh is best’.

1. Erridge, C., Attina, T., Spickett, C. M., & Webb, D. J. (2007). A high-fat meal induces low-grade endotoxemia: evidence of a novel mechanism of postprandial inflammation. The American Journal of Clinical Nutrition, 86(5), 1286–1292. doi:10.1093/ajcn/86.5.1286 
2. Kim, K. A., Jeong, J. J., Yoo, S. Y., & Kim, D. H. (2016). Gut microbiota lipopolysaccharide accelerates inflamm-aging in mice. BMC microbiology, 16, 9. doi:10.1186/s12866-016-0625-7
3. Herieka, M., Faraj, T. A., & Erridge, C. (2016). Reduced dietary intake of pro-inflammatory Toll-like receptor stimulants favourably modifies markers of cardiometabolic risk in healthy men. Nutrition, Metabolism and Cardiovascular Diseases, 26(3), 194-200.
4. Erridge, C. (2011). The capacity of foodstuffs to induce innate immune activation of human monocytes in vitro is dependent on food content of stimulants of Toll-like receptors 2 and 4. British journal of nutrition, 105(1), 15-23.
5. Wassenaar, T. M., & Zimmermann, K. (2018). Lipopolysaccharides in Food, Food Supplements, and Probiotics: Should We be Worried?. European journal of microbiology & immunology, 8(3), 63–69. doi:10.1556/1886.2018.00017
6. Boutagy, N. E., McMillan, R. P., Frisard, M. I., & Hulver, M. W. (2016). Metabolic endotoxemia with obesity: Is it real and is it relevant? Biochimie, 124, 11–20. doi:10.1016/j.biochi.2015.06.020 

Recent research into circadian rhythms shows that the time of day when food is
ingested influences nutrient absorption, assimilation and utilisation. This had led to a dramatic increase in research into the possible benefits of time-restricted eating (TRE). TRE suggests benefits in narrowing the time-window for eating and raises the question whether the largest meal is best consumed at the beginning or end of the day.
 
‘When we eat may be as important as what we eat.’
 
Humans evolved with cyclic periods of fasting and feeding. These adapted temporal rhythms act at the cellular level switching between nutrient utilisation and storage. Fasting-feeding cycles are known to acutely activate nutrient-sensing pathways in what is termed the ‘molecular clock’.
 
The circadian molecular clock ensures that gene expression and appropriate pathways that help assimilate nutrients begin to rise in anticipation of feeding, so the body can handle the rush of nutrients in an optimal way and maintain nutrient balance.
 
Circadian fasting-feeding cycles affect metabolism

The time of day wen food is ingested exerts a powerful influence on metabolic health including:

• body composition and size
• hunger and satiety
• liver health
• blood sugar and cholesterol
• neuroendocrine function
• the gut microbiome
• heart function
• inflammation
• sleep

 
A current hotly debated topic is what time of the day should the largest meal be consumed. It is well established that after eating, blood glucose remains higher in the evening than in the morning. This research been put to the test with human clinical trials, to once and for all answer these common questions:

• Is it better to consume the main meal in the first or last half of the day?
• Is it safe to skip breakfast, lunch or dinner?

 
According to researcher Chaix (2019), restricting the time of food access for example to an 8-10 hour window during the day, not only reduces obesity, but activates multiple longevity factors, which may help halt chronic disease.  Studies where the majority of food is consumed in the first half of the day and less in the second half of the day, reduced inflammation, improved blood sugar control and produced better weight loss and reductions in hunger. In fact, research suggest, breakfast skipping may have detrimental health effects and lead to late night binge-eating.
 
For those wanting to reduce their weight and improve metabolic and hormonal health, a personalised time-restricted eating program from a health-care professional may offer an efficient and easy way to maintain a healthy weight and improve longevity.
 
Bibliography:
Chaix, A., Manoogian, E. N. C., Melkani, G. C., & Panda, S. (2019). Time-Restricted Eating to Prevent and Manage Chronic Metabolic Diseases. Annual Review of Nutrition, 39(1). 
Jakubowicz, D., Barnea, M., Wainstein, J., & Froy, O. (2013). High Caloric intake at breakfast vs. dinner differentially influences weight loss of overweight and obese women. Obesity, 21(12), 2504–2512.
Laermans, J., & Depoortere, I. (2016). Chronobesity: role of the circadian system in the obesity epidemic. Obesity reviews, 17(2), 108-125