A Moving Target
Health claims and dietary guidelines seem about as stable as Michigan weather—wait a moment and things’ll change.
That Perhaps Hasn’t Moved Far Enough
But sometimes, guidelines should change. Consider this:
Although study after study has demonstrated the many benefits of tea and coffee, our federal dietary guidelines for Americans for 2015–2020 first say
“when choosing beverages, both the calories and nutrients they provide are important considerations. Beverages that are calorie-free—especially water—or that contribute beneficial nutrients, such as fat-free and low-fat milk and 100% juice, should be the primary beverages consumed,”
followed by a tepid
“coffee, tea, and flavored waters also can be selected” (USDHHS 2015:61).
Not exactly a ringing endorsement of coffee or tea, even for those of us who drink our tea and coffee black.
And although milk might well be part of a balanced diet, the endorsement of juice (which, as many nutritionists caution, is far less healthy than eating whole fruit) over coffee and tea? Seriously?
And as far as water goes, some have suggested that tea—with its many beneficial polyphenols—is even healthier than plain water!
New Reasons Why Coffee and Tea May Be Healthier
It seems that tea impacts cognition. The more tea consumed, the lower the rates of functional disability and dementia, according to many studies that look at how polyphenols (micronutrients in plants) protect the brain.
But new research indicates that caffeine also offers some protection against dementia!
A recently published study on the caffeine-dementia link spent ten years following nearly 6,500 healthy women who were 60–80 years old and without dementia when the research began (Driscoll et al. 2016). Because this study was embedded in another project, it isn’t as exact as one might wish.
For one, the women self reported, not the most reliable way to compile data.
Secondly, via questionnaire, the women were asked simply if they drank coffee, tea, and/or cola. The researchers assumed these were caffeinated. And although the women were asked how much of each of these they drank, only the amounts of coffee were used to estimate caffeine levels.
Say Yes to Caffeine (and No to Dementia)!
However, the study results were striking.
Of the women who consumed higher amounts of caffeine on a day-to-day basis, fewer of them developed probable dementia or global cognitive impairment (during the study’s duration) as compared to the women who drank lower amounts of caffeine daily.
So How Much Caffeine Are We Talking?
The mean amount of caffeine for everyone in the study was 172 mg/day, which translates to about 14–15 oz of coffee or 29–30 oz of tea a day (Driscoll et al. 2016:4).
The mean of the group that had fewer cases of dementia was 261 mg of caffeine/day (Driscoll et al. 2016:4).
This is about 3 cups of coffee (22 oz) or 5.5 cups of tea (44–45 oz) per day.
But Does the Caffeine Have to Be in Coffee or Tea?
The researchers acknowledge the limitations of their study, writing that “the source of caffeine may be an important consideration for future research” (Driscoll et al. 2016:5). Indeed, while I don’t think that getting caffeine from soda would outweigh the ill effects of drinking soda, what about supplemental caffeine in the form of pills?
Also, I wonder if there were women who didn’t drink a lot of coffee but did drink a lot of tea—their caffeine levels would be considered low in this study, which may not be entirely accurate.
BUT, Is It the Caffeine or the Polyphenols?
Because this project was based on nonhuman studies on the caffeine-cognition connection, the researchers were looking specifically at caffeine levels. But coffee and tea also have polyphenols, and the more coffee/tea ingested, the more polyphenols and caffeine ingested.
Because polyphenols have also been shown to protect against dementia, the effects of caffeine vs the effects of polyphenols must be teased apart, especially if they are to be used pharmacologically. It is also possible that caffeine and phenols are working synergistically.
So does caffeine protect against dementia? Maybe.
But we can say that this exciting news from Driscoll’s team offers greater insight into how we may—one day—be able to treat, and possibly even prevent, cognitive decline.
In other words? It give us hope.
Sources: (1) Driscoll, I., et al. “Relationships between caffeine intake and risk for probable dementia or global cognitive impairment: The Women’s Health Initiative memory study,” J Gerontol A Biol Sci Med Sci, adv access publ:1–7. Sept. 21, 2016. (2) U.S. Department of Health and Human Services and U.S. Department of Agriculture, Dietary Guidelines for Americans 2015–2020, 8th ed. Dec. 2015.
Prior posts on caffeine in tea:
The Case for Caffeine
Why Doesn’t Tea Make Me Wired?
Caffeine in Tea: How Much Is in Your Brew?
Prior posts on the protective benefits of tea against dementia:
Protective Power of Tea
Black Tea’s Protective Power
Protective Power of Tea–3