Before getting to this month’s “Science Notes,” there is something I want to add to the piece that I wrote in this column in December, about mimicry in nature and biomimicry: It is an example of mimicry in orchid odors.
While some species of orchids attract pollinators by mimicking different plant species, others do so by emitting odors that attract their pollinators. The blunt-leaved bog orchid, found growing in New England forests, fields, and bogs, is unique in two respects: It is the only species of orchid known to be pollinated by mosquitoes, and its other claim to fame is the odor it emits.
I recently came across a note in the Jan. 8 issue of the journal Science about unpublished research carried out by biologists at the University of Washington in Seattle. Jeff Riffell and Chloé Lahondère and their colleagues have discovered that the plant emits an odor that mimics human body odor, and that it thus attracts tiger mosquitoes, the plant’s pollinator. According to these scientists, the human body odor causes an electrical signal in the antennae of the mosquitoes that attracts them to the bog orchid. I wonder how the plant achieved the ability to mimic body odor.
I corresponded with Jeff, and learned that he and his colleagues are still working to identify the volatile chemicals in human body odor used by the orchid to mediate their association with the mosquitoes. He said that they are very excited, because they believe that the results of their research will provide a source for natural attractants, allowing their use in lures to survey local mosquito populations, and possibly as deterrents, since other orchid species are not visited by mosquitoes but emit a different scent to attract their own pollinators.
We will have to wait for the published paper to learn more about this mimic.
Deciphering the guidelines
Now to the subject of this month’s “Science Notes.” You have probably read or heard about the eighth edition of “Dietary Guidelines for Americans 2015-2020,” issued last month by the Department of Health and Human Services and the Department of Agriculture (see usda.gov). A food-conscious friend skimmed the guidelines’ 124 pages. He was confused, and told me that he had been happy with the previous edition, was loath to change his eating habits, and asked why there was need for a new edition.
I worked my way through the entire document before I answered my friend’s question of why the new edition. I am far from being a nutrition scientist. Nevertheless, I came up with sort of an answer for my friend.
Our understanding of nutrition changes as we gain knowledge of human genetics, chemistry, and physiology, and now the awareness of the importance of the human microbiome, the bacteria in our gut, that play important roles in our health.
There is an important caveat regarding our belief in following the guidelines. We must bear in mind the question of how much of what the government agencies propose is influenced by the food-industry lobby, and we need to watch for sales hype, on the web and elsewhere.
With this warning, here are a few highlights of the recent recommendations.
The Mediterranean diet is still in, and so is even fat, in moderation, but sugar is out. Coffee is in, and red wine hangs in there, and certainly vegetables, fruit, and nuts.
The inclusion of coffee is interesting, because researchers at Harvard’s School of Public Health have shown that coffee has many benefits. In a study published last year, they reported the results of health data regarding coffee drinking gathered over 30 years from more than 160,000 women and 40,000 men. Reduced risk of death from heart disease, diabetes, neurological diseases, and suicide were all associated with moderate coffee consumption. The study points out the complexity of dietary guidelines, because coffee can have different beneficial effects on men and women. For example, it may reduce the risk of tinnitus in women, and in men the risk of fatal prostate cancer.
To add to that study, a more recent one by the Harvard researchers reveals that at least two genes control the desire for caffeine.
The bottom line is that coffee in moderation can be good for you, particularly if you forgo large amounts of cream and sugar.
Fruit and vegetables hold a high position in the hierarchy of the Dietary Guideline because they contain relatively high concentrations of flavonoids that are antioxidants and anti-inflammatory agents.
Antioxidants scavenge free radicals that can cause cellular and intracellular
damage. The anti-inflammatory flavonoids combat the inflammatory effects of many foods. High on the list for the flavonoids are red grapes, berries, high-cacao low-sugar chocolate, coffee, and red wine. Very cautious choices of websites can provide valuable information. But always stay away from the sales pitches, and keep in mind that the guidelines may be different five years from now, when the next edition is published.
In the end, consider sticking to getting no more than 10 percent of your daily calories from added sugar; also, no more than 10 percent from saturated fat replaceable with unsaturated and polyunsaturated fat. Three to five 8-oz. cups of coffee appear to be OK, but remember — with limited cream and sugar.
And here is a tough one. The guidelines say that eating processed meat and poultry is acceptable, even if they contain high levels of salt. I am not sure I agree with that one.
Meanwhile, let us toast the new guidelines by raising our glasses of red wine or cups of coffee, while nibbling on red grapes and chocolate.
Retired Stanford professor and West Tisbury resident Paul Levine contributes this monthly column devoted to scientific research taking place today, along with profiles of Island scientists and their work, and facts of scientific note on Martha’s Vineyard.