Newsletter #249

Hey guys! So, I recently stumbled upon a couple of studies showing some unique benefits linked to zinc (both supplementally and from food), which I thought would be worth taking a closer look at. Worldwide, it has been estimated that around 17% of the population does not consume adequate zinc, although it is less likely to be an issue in developed countries like the US.

As you’ll see, the findings from both of these studies should probably be taken with a grain of salt. However, if you log your food intake and find that you're consistently low in zinc or you eat a diet that increases your zinc need (vegetarians may require a little bit more since zinc availability is lower from plant foods), I think taking a zinc supplement or a multi-mineral is probably not an unreasonable precaution.

Telomeres are structures at the ends of chromosomes that help prevent chromosomes from sticking together or fraying (sort of like the caps at the ends of shoelaces). Unfortunately, they tend to accumulate damage over time through exposure to oxidative stress and inflammation, which causes them to shorten. Premature telomere shortening is linked to earlier onset of age-related disease, as well as earlier death from all causes, which is why telomere length is now treated as a biomarker of biological age and life span. For this reason, scientists have become interested in how healthy diets, as well as specific nutrients, may help insulate telomeres from damage and thus preserve their length. To examine how zinc intake might influence telomere length, researchers analyzed dietary data from 3793 middle-aged participants in the National Health and Nutrition Examination Survey (NHANES). After adjusting for numerous confounders, including age, sex, race, BMI, education, household income, etc, every 5 mg increment of zinc consumption was linked to 0.64% greater telomere length. When the researchers further adjusted for energy intake, the association of dietary zinc intake and telomere length remained statistically significant in women (percentage change: 1.11%), individuals with obesity (percentage change: 0.88%), and in those whose caloric intake was below the average for the sample (percentage change: 0.99%). It’s not super clear why the benefits would be confined to these groups. But why might zinc have this effect in general? Well, prior research has suggested that diets rich in anti-inflammatory and antioxidant compounds are associated with longer telomeres. Accordingly, the researchers speculate that the antioxidant and anti-inflammatory effects of zinc could shield telomeres from DNA damage due to oxidative stress and pro-inflammatory proteins. It may also partially explain another benefit of zinc, which we discuss below.

Brain-derived neurotrophic factor (BDNF) is a protein that helps brain cells grow and connect to one another, and is essential for learning and long-term memory. For that reason it is sometimes referred to as "fertilizer for your brain." Physical activity is known to reliably increase levels of BDNF and this rise is thought to underlie some of the cognitive benefits associated with exercise. Furthermore, alterations in levels and signaling of BDNF are linked to neurodegenerative disease, so there's a ton of interest in ways to modulate this neurotrophin. To examine how zinc might interact with circulating BDNF, researchers performed a meta-analysis of randomized controlled trials that examined how zinc supplementation influenced circulating levels of BDNF (compared to placebo). They were only able to identify four such trials, which enrolled a total of 185 participants, and all of which administered zinc for about three months. The analysis showed that three of the trials, which administered zinc gluconate in doses of 30 mg per day, increased BDNF levels with a small-moderate effect size. (One trial, which gave patients with depression a different form of zinc in a slightly lower dose, failed to find a significant effect.) The researchers suggest that this finding could be attributed to zinc’s action as a cofactor for enzymes that convert BDNF into its active form. Furthermore, the aforementioned anti-inflammatory effects of zinc may be playing a role here. It has been observed that inducing inflammation experimentally can lower BDNF, and conditions associated with inflammation in the brain are often accompanied by low levels of BDNF. It's worth noting that the size of the effect here is pretty modest, especially compared to high intensity interval training, which remains the best known way to elicit higher BDNF. That having been said, we know that inflammatory stimuli can "block" the natural rise in serum BDNF associated with physical activity, so a nutrient-rich, anti-inflammatory diet is probably a smart move regardless.

In this “Brainjo Bite,” entitled “Can Music Save Your Brain,” Josh dives into the link between cognitive activity and brain tissue health and function.

“It’s clear that a cognitively active lifestyle is associated with a significant reduction in the risk of cognitive decline and dementia, but how? And are certain kinds of activities better than others?”

✍️ The longest word in English is the chemical composition of titin — the protein that makes our skeletal muscles springy and elastic.

It is the largest human protein, so it’s not too surprising that its chemical composition is horribly convoluted. I should note that it is kind of debatable whether this properly counts as a word, since it is a technical term that obviously did not emerge organically, it does not appear in any English dictionaries, and it hasn't even appeared in full in any publication.

For both your sake and mine, I will not actually insert the word in this newsletter, but you can see it here.

By the way, some guy on youtube, who must be a serious glutton for punishment, actually tried to pronounce the whole thing and the subsequent recording is nearly two hours long. 💀

Neurotrophic Factors and Blood Flow — from Nutrients for Thinking

This week, I’d like to highlight one of the lessons from our Daily Performance Program.

This lesson examines how components in foods, such as flavonoids, could both enhance cognitive performance and protect the brain from degenerative diseases. They may accomplish this in part by boosting growth factors like BDNF (we already saw that zinc appears to do this, which is pretty cool), but also by increasing blood flow to the brain.

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