Does eating an avocado every day improve the diversity of your gut microbiome?
Eating an avocado every day likely increases the diversity of your gut bacteria, although the evidence comes primarily from people with overweight. If you have a healthy weight, the effect has not yet been demonstrated.
Eating an avocado every day increases the diversity of gut bacteria. Two separate randomised studies, conducted in adults with overweight or abdominal obesity, both found a significantly greater variety of gut bacteria in the avocado group compared with a control group. In one study this effect was already visible after 4 weeks and persisted through to week 26. The difference was greatest in people who already had a less varied diet to begin with.
Both studies also observed an increase in a specific bacterium, Faecalibacterium prausnitzii, a bacterium linked to a healthy gut wall and to helping counteract inflammation. In one study this bacterium increased by 26 to 65% relative to the control group, along with other fibre-fermenting bacteria.
Avocado also affects what gut bacteria produce. Participants who ate an avocado daily had more acetate in their stool, a substance that gut bacteria produce when processing fibre and that is beneficial for the gut wall. At the same time, concentrations of certain bile acids in their stool were considerably lower. High bile acid concentrations in the gut are associated with gut irritation.
A caveat: despite the shifts in bacterial composition, one of the studies found no difference in what those bacteria actually do, that is, in their metabolic activity. The bacterial community looks different, but whether the gut actually functions differently is less clear. In addition, all participants in both studies were people with overweight or abdominal obesity. Whether the same applies to people with a healthy weight has not yet been investigated. A laboratory study on an extract of avocado skin shows preliminary indications of similar effects, but those results cannot be translated directly to eating an ordinary avocado every day.
This answer is based on two randomised studies involving a combined total of more than 390 participants, and one laboratory study without human subjects. The two randomised studies are methodologically the strongest and both point in the same direction; the findings are therefore better supported than in most nutritional studies. However, the participants were exclusively adults with overweight or obesity, which limits how broadly the results can be applied to the general population.
Is there a relationship between changing body odour and Alzheimer's disease?
Loss of smell is a well-documented early sign of Alzheimer's disease, and changes in body odour are being investigated as a possible marker, but a clinically usable 'smell test' for Alzheimer's disease does not yet exist.
Do you live longer if you eat more salt?
Eating more salt does not lead to a longer life. At the individual level, it demonstrably increases the risk of cardiovascular disease, and salt restriction lowers blood pressure and the risk of premature death.
Does extra salt help with fatigue during fasting?
Baking soda (sodium bicarbonate) reduced fatigue in trained men who had fasted and then exercised, but this was found in only one small study and says nothing about everyday fasting-related fatigue. Ordinary table salt has not been studied for this purpose.