From the Washington Post September 23, 2019 -
Lutein supplements are everywhere. Here’s what you need to know about this nutrient.
September 23, 2019 at 7:00 a.m. EDT
They
were the bright yellow in the calendula flowers, the ocher streaks in
the tomato skins, the yellow-green of the sorrel and kale, and the topaz
of the turning maple leaves. They were the darker green of the delicate
lamb’s quarters and serrated dandelion greens. And because nature is
thrifty and likes to make the most of any useful substance, they were
also the burnt umber in the wings of a passing butterfly. And yes, they
are in us as well.
Xanthophylls
are antioxidants in the carotenoid family, and lutein and zeaxanthin
(or L/Z, as they are often denoted) are the main xanthophylls found in
food. We can’t synthesize xanthophylls, or any carotenoids for that
matter, so we get them by eating plants that make them or animals — such
as chicken and fish — that also eat plants. Despite their availability
in nature, I am seeing lutein and zeaxanthin supplements sold
everywhere.
It appears that L/Z are the nutrition boost du jour; their market share is growing
and is expected to reach $396 million in 2024. An entire shelf in my
local drugstore is dedicated to lutein-containing supplements, and I’m
now spotting L/Z on eyedrops and in face creams, dairy products, sports
drinks, fruit juices and baby formula. Some egg producers, whose
products already have lutein naturally, are fortifying their eggs with
the stuff.
Why
such hunger for L/Z, particularly lutein? After all, they are just two
of the 30-plus carotenoids that are found in the human body, with other
notable ones being lycopene and beta carotene, an antioxidant we convert
to vitamin A.
“Lutein
is a major workhorse molecule,” said Billy Hammond, a neuroscientist at
the University of Georgia who studies the role of these compounds in
eye and brain health. Other carotenoids are found in our kidneys, livers
skin, immune system, fat cells and so on, but lutein and zeaxanthin are
the main carotenoids in our macula (the vision center of the eye) and
brain.
Without
these colorful compounds, we would be stumbling in the dark, blinded by
light, and terrible drivers. We would also be missing every fly we
tried to swat (or baseball, for that matter) and our balance would be
shaky. There is also strong evidence
that lutein and zeaxanthin protect against age-related macular
degeneration, the leading cause of blindness in the United States and
most industrialized countries. Neuroscientists are discovering that we
need an adequate stockpile of xanthophylls to reason, learn new things
and ward off dementia. Two newly
published studies suggest that low blood levels of L/Z can be a
harbinger of frailty — the inability to bounce back from an illness — in
older adults.
Perhaps
one of the reasons that we are hearing so much about L/Z is because
there is a noninvasive way to measure them. While most nutrients from
foods or supplements are challenging to trace once they enter the cavern
of the human body, lutein and zeaxanthin are 100 times more
concentrated in the macula than elsewhere, and their density can be
studied using a fancy desktop ophthalmoscope. This measurement, called
Macular Pigment Ocular Density (MPOD) correlates well with blood levels
of the compounds and with the amount we ingest. Conveniently, MPOD also
correlates with objective tests of eye and brain function such as how
fast we process visual stimuli.
“We
have found that most people are in a deficiency state and would get a
big benefit from just getting to normal,” Hammond said. His research
shows that even young, healthy athletes can improve their eye and brain
performance when they boost their levels of L/Z, and he estimates that
this benefit only increases as we age.
John
Erdman, a nutrition scientist at the University of Illinois who has
spent much of his career studying carotenoids, agrees with Hammond. In a
recent article in the European Journal of Nutrition,
he and his colleagues argue that the sum of the evidence in favor of
lutein is so strong that the Institute of Medicine, the group that sets
the Daily Recommended Intake
of other nutrients, should include lutein on the list. “Establishing
dietary guidance for lutein would encourage people to eat
lutein-containing foods and raise public awareness about the potential
health benefits,” he said, adding that other compounds with much less
evidence of benefit, such as fluoride, have made the list.
So, ideally how much L/Z do we need? Do we really need to shop the nutraceutical aisles or buy fortified eggs to get it?
Both
Hammond and Erdman estimate, based on the available research, that we
need about 12 mg of lutein and 2 mg of zeaxanthin a day, and yet the
average American adult gets about one-tenth that amount. As for how to
increase our lutein intake, “Food is always the better choice,” Hammond
said. Supplements, on the other hand, are better for research, he said,
because study subjects can’t differentiate them from placebos and the
researchers know exactly how much of a given substance they are
administering. (Hammond’s research is partially funded by nutraceutical
companies.)
Though
food’s complexity makes it tougher to measure any effect on our health,
that complexity makes food a better choice for adding lutein to your
diet. Consider spinach, a lutein-packed food. Roughly three cups of raw
leaves gives you your daily dose of lutein, but because carotenoids are
fat soluble, mixing that spinach with an olive oil dressing will greatly
increase your absorption of the compound.
Cooking
also makes the carotenoid more bioavailable. Many traditional recipes
from around the globe are lutein and zeaxanthin bombs, including saag,
a tasty North Indian dish of simmered spinach mixed with yogurt; the
Middle Eastern side dish of roast carrots tossed in za’atar spices and
olive oil; and the Mesoamerican classic combo
of tomato salsa, cilantro, avocado, and corn tortillas or tortilla
chips. To check out how much lutein and zeaxanthin is in your dinner,
you can use a calculator when you search “food composition database” on the Agriculture Department website.
In
the quest for xanthophyll-rich meal, the cultivar (or specific genetic
traits) of any fruit or vegetable can add yet another level of
complexity. Take your classic supermarket Cavendish banana. It has
negligible amounts of lutein, but researchers have
found that the Hung Tu, a lesser-known banana indigenous to Papua New
Guinea, has 30 times as much of this carotenoid. Eggs are generally a
good source of lutein and zeaxanthin, but the amounts of these compounds
vary depending on the breed of hen, what she gets in her diet
(marigolds are good) and how she spends her day. One study
suggests that pastured hens deposit more lutein and zeaxanthin into
their egg yolks. Note to the egg-whites-only crowd: You will be missing
out on these bioactive compounds.
There are some instances when supplemental lutein and zeaxanthin is in order. The Age-Related Eye Disease studies,
two large multicenter trials, make a convincing case for taking L/Z
early if you are diagnosed with macular degeneration, because they might
prevent progression to more serious disease. Older people might also
need a supplement boost because they are less likely to absorb L/Z
through the intestinal lining. Some studies
show that people who are inactive, overweight or have diabetes
generally have lower blood levels of lutein and zeaxanthin. Of course,
these are observational studies, so it’s not clear which is the chicken
and which is the lutein-enriched egg.
“The bottom line,” Hammond said, “is that most people just don’t eat enough fruits and vegetables.”
I
told him about the xanthophyll inventory I had made in my own garden —
how it seemed to be everywhere. “Yes,” he said, “my work is always
reminding me that we are one with nature, that we integrate plants into
our own biology. Sadly, we are making parking lots of our bodies, just
like we are doing with the forests.”
