Chapter 22
Lifestyle+ — 13
In older people, the impact of the Mediterranean diet on the gut microbiome has been assessed in a randomized trial of more than twelve hundred participants, aged sixty-five to seventy-nine years, compared with a habitual control diet. The Mediterranean diet promoted bacterial taxa associated with less frailty, reduced inflammation, and improved cognitive function. Diets of plant-based fiber and high in fermented foods (such as yogurt, cheese, and kombucha) have been shown to favorably modulate the gut microbiome, foster its diversity, and reduce immune-mediated inflammation.
Can we do better than the Mediterranean diet? A smaller randomized trial in 294 people with obesity, but no heart disease, tested three diets: Mediterranean, the green MED diet (adding walnuts, green tea, and a Mankai plant-based protein shake, with less meat and poultry), and healthy dietary guidance. The green MED diet showed some advantages over the Mediterranean diet by lowering low-density lipoprotein (LDL) cholesterol, inflammatory markers, blood pressure, and weight reduction. But this small trial only looked at blood markers and was insufficiently large to determine an effect on outcomes. While there may ultimately be a diet validated through randomized trials to be healthier, with better outcomes, than the Mediterranean diet, we haven’t seen it to date.
Beyond an overall healthy food diet, there are some intriguing amino acids that deserve more attention than they have received. Taurine is not one of the nine essential amino acids (histidine, leucine, isoleucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine) we can obtain only from our diet. Much of the aggregate data supports that taurine decreases as we age (and in all species that have been assessed) and that its deficiency has been associated with diabetes, hypertension, liver disease, abdominal obesity, and inflammation. Everything about taurine has the look of it being a driver of antiaging, from suppressing mitochondrial dysfunction, to decreasing DNA damage and inflammation, to reducing cellular senescence. The impact of six months of taurine supplementation to aged rhesus monkeys, equivalent to humans ages forty-five to fifty years, was notable for promoting health span: a 19 percent reduction in fasting glucose, increased bone density, and improvement of markers of mitochondrial function, liver function, and immune system. Taurine-rich foods include shellfish, especially scallops, clams, and mussels, and dark meat of turkey and chicken. Other good sources are brewer’s yeast, milk, yogurt, cheese, and peanuts. It is not generally found in any plant foods, except red algae. Whether to take a taurine supplement to promote healthy aging has not been established and is thus far without verification from any randomized trials.
Choline is an organic compound, not an amino acid, that is considered an essential nutrient that must come from our diet. It is important for multiple brain functions. Rich sources are eggs (particularly the yolk), beef, milk, shitake mushrooms, soybeans, chicken breast, cauliflower, broccoli, and fish. The National Academy of Medicine has recommended 550 milligrams or 425 milligrams per day for men and women, respectively. Like the nine essential amino acids that we must obtain from our diet, ingestion of choline, at the level recommended, is usually not an issue on a diet of the healthy foods reviewed above. For people aged sixty-five and older, choline supplementation has been linked with improved cognitive performance, but, again, randomized trials will be necessary to resolve this question.