The China Study (33 page)

WIDE-RANGING EFFECTS: BONE, KIDNEY, EYE, BRAIN DISEASES             215
among people over age sixty-five. Over l.6 million Americans suffer
from this disease, many of whom become blind. 39 As the name implies,
this condition involves destruction of the macula, which is the bio-
chemical intersection in the eye-where the energy of the light coming
in is transformed into a nerve signal. The macula occupies center stage,
so to speak, and it must be functional for sight to occur.
Around the macula there are fatty acids that can react with incoming
light to produce a low level of highly reactive free radicals.40 These free
radicals (see chapter four) can destroy, or degenerate, neighboring tis-
sue, including the macula. But fortunately for us, free radical damage
can be repressed thanks to the antioxidants in vegetables and fruits.
Two studies, each involving a team of experienced researchers at
prestigious institutions, provide compelling evidence that food can pro-
tect against macular degeneration. Both studies were published a decade
ago. One evaluated diet4! and the other assessed nutrients in bloodY
The findings of these two studies suggested that as much as 70-88%
of blindness caused by macular degeneration could be prevented if the
right foods are eaten.
The study on dietary intakes4! compared 356 individuals fifty-five to
eighty years of age who were diagnosed with advanced macular degen-
e r a t i o n (cases) with 520 individuals with other eye diseases (controls).
Five ophthalmology medical centers collaborated on the study.
Researchers found that a higher intake of total carotenoids was as-
s o c i a t e d with a lower frequency of macular degeneration. Carotenoids
are a group of antioxidants found in the colored parts of fruits and veg-
e t a b l e s . W h e n carotenoid intakes were ranked, those individuals who
consumed the most had 43% less disease than those who consumed the
least. Not surprisingly, five out of six plant-based foods measured also
were associated with lower rates of macular degeneration (broccoli, car-
rots, spinach or collard greens, winter squash and sweet potato). Spin-
a c h or collard greens conferred the most protection. There was 88% less
disease for people who ate these greens five or more times per week
when compared with people who consumed these greens less than once
per month. The only food group not showing a preventive effect was the
cabbage/cauliflower/brussels sprout group, which sports the least color
of the six food groupS.43
These researchers also looked at the potential protection from dis-
ease as a result of the consumption of five of the individual carotenoids
consumed in these foods. All but one of these five showed a highly
r
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THE CHINA STUDY
216
significant protective effect, especially the carotenoids found in the
dark green leafy vegetables. In contrast, supplements of a few vitamins,
including retinol (preformed "vitamin" A), vitamin C and vitamin E
showed little or no beneficial effects. Yet again, we see that while sup-
p l e m e n t s may give great wealth to supplement manufacturers, they will
not give great health to you and me.
When all was said and done, this study found that macular degenera-
tion risk could be reduced by as much as 88%, simply by eating the right
foodsY
At this point you may be wondering, "Where can I get some of those
carotenoids?" Green leafy vegetables, carrots and citrus fruits are all
good sources. Herein lies a problem, however. Among the hundreds
(maybe thousands) of antioxidant carotenoids in these foods, only a
dozen or so have been studied in relation to their biological effects. The
abilities of these chemicals to scavenge and reduce free radical damage
are well established, but the activities of the individual carotenoids vary
enormously depending on dietary and lifestyle conditions. Such varia-
tions make it virtually impossible to predict their individual activities,
either good or bad. The logic of using them as supplements is much too
particular and superficial. It ignores the dynamic of nature. It's much
safer to consume these carotenoids in their natural context, in highly
colored fruits and vegetables.
The second study42 compared a total of 421 macular degeneration
patients (cases) with 615 controls. Five of the leading clinical centers
specializing in eye diseases and their researchers participated in this
study. The researchers measured the levels of antioxidants in the blood,
rather than the antioxidants consumed. Four kinds of antioxidants were
measured: carotenoids, vitamin C, selenium and vitamin E. Except for
selenium, each of these nutrient groups was associated with fewer cases
of macular degeneration, although only the carotenoids showed statisti-
cally significant results. Risk of macular degeneration was reduced by
two-thirds for those people with the highest levels of carotenoids in
their blood, when compared with the low-carotenoid group.
This reduction of about 65-70% in this study is similar to the reduc-
t i o n of upwards of 88% in the first study. These two studies conSistently
demonstrated the benefits of antioxidant carotenoids consumed as
food. Given experimental limitations, we can only approximate the pro-
p o r t i o n of macular degeneration caused by poor dietary habits, and we
cannot know which antioxidants are involved. What we can say, howev-

WIDE-RANGING EFFECTS: BONE, KIDNEY, EVE, BRAIN DISEASES           217
er, is that eating antioxidant-containing foods, especially those contain-
i n g the carotenoids, will prevent most blindness cases resulting from
macular degeneration. This in itself is a remarkable recommendation.
Cataracts are slightly less serious than macular degeneration because
there are effective surgical options available to restore vision loss caused
by this disease. But when you look at the numbers, cataracts are a much
larger burden on our society. By the age of eighty, half of all Americans
will have cataracts. 39 Currently there are 20 million Americans age forty
and older with the disease.
Cataract formation involves the clouding of the eye lens. Corrective
surgery involves removing the cloudy lens and replacing it with an arti-
ficiallens . The development of the opaque condition, like the degenera-
t i o n of the macula and so many other disease conditions in our body, is
closely associated with the damage created by an excess of reactive free
radicals. 44 Once again, it is reasonable to assume that eating antioxi-
d a n t - c o n t a i n i n g foods should be helpful.
Starting in 1988, researchers in Wisconsin began to study eye health
and dietary intakes in over 1,300 people. Ten years later, they published
a report4 5 on their findings. The people who consumed the most lutein,
a specific type of antioxidant, had one-half the rate of cataracts as the
people who consumed the least lutein. Lutein is an interesting chemical
because, in addition to being readily available in spinach, along with
other dark leafy green vegetables, it also is an integral part of the lens
tissue itself. 46 , 47 Similarly, those who consumed the most spinach had
40% less cataracts,
These two eye conditions, macular degeneration and cataracts, both
occur when we fail to consume enough of the highly colored green and
leafy vegetables, In both cases, excess free radicals, increased by animal-
based foods and decreased by plant-based foods, are likely to be respon-
sible for these conditions,
MIND-ALTERING DIETS
By the time this book hits the shelves, I will be seventy years old, I
recently went to my high school's fiftieth reunion, where I learned that
many of my classmates had died, I receive the AARP magazine, get
discounts on various products for being advanced in age and receive
social security checks every month. Some euphemists might call me a
"mature adult," I just say old, What does it mean to be old? I still run
every morning, sometimes six or more miles a day. I still have an active

THE (HINA STUDY
218
work life, perhaps more active than ever. I still enjoy all the same leisure
activities, whether visiting grandchildren, dining with friends, garden-
ing, traveling, golfing, lecturing or making outdoor improvements like
building fences or tinkering with this or that as I used to do on the farm.
Some things have changed, though. Clearly there is a difference between
the seventy-year-old me and the twenty-year-old me. I am slower, not aS        I
strong, work fewer hours every day and am prone to taking naps more             !
l
frequently than I used to.
We all know that getting old brings with it diminished capacities
compared with our younger days. But there is good science to show that
thinking clearly well into our later years is not something we need to
give up. Memory loss, disorientation and confusion are not inevitable
parts of aging, but problems linked to that all-important lifestyle factor:
diet.
There is now good dietary information for the two chief conditions
referring to mental decline. On the modest side, there is a condition
called "cognitive impairment" or "cognitive dysfunction." This condi-
t i o n describes the declining ability to remember and think as well as one
once did. It represents a continuum of disease ranging from cases that
only hint at declining abilities to those that are much more obvious and
easily diagnosed.
Then there are mental dysfunctions that become serious, even life
threatening. These are called dementia, of which there are two main
types: vascular dementia and Alzheimer's disease. Vascular dementia is
primarily caused by multiple little strokes resulting from broken blood
vessels in the brain. It is common for elderly people to have "silent"
strokes in their later years. A stroke is considered silent if it goes un-
d e t e c t e d and undiagnosed. Each little stroke incapacitates part of the
brain. The other type of dementia, Alzheimer's, occurs when a protein
substance called beta-amyloid accumulates in critical areas of the brain
as a plaque, rather like the cholesterol-laden plaque that builds up in
cardiovascular diseases.
Alzheimer's is surprisingly common. It is said that 1% of people at
age sixty-five have evidence of Alzheimer's, a figure that doubles every
five years thereafter. 48 I suppose this is why we blandly accept "senility"
as part of the aging process.
It has been estimated that 10-12% of individuals with mild cognitive
impairment progress to the more serious types of dementia, whereas
only 1-2% of individuals without cognitive impairment acquire these

WIDE-RANGING EFFECTS: BONE, KIDNEY, EYE, BRAIN DISEASES            219
diseases _9, 50 This means that people with cognitive impairment have
"
about a tenfold risk of Alzheimer's.
Not only does cognitive impairment often lead to more serious de-
mentia, it is also associated with cardiovascular disease,51-53 strokes" and
adult-onset Type 2 diabetes. 55, 56 All of these diseases cluster in the same
populations, oftentimes in the same people. This clustering means that
they share some of the same risk factors . Hypertension (high blood
pressure) is one factoyS1, 57, 58; another is high blood cholesterol. 53 Both
of these, of course, can be controlled by diet.
A third risk factor is the amount of those nasty free radicals, which
wreak havoc on brain function in our later years. Because free radical
damage is so important to the process of cognitive dysfunction and
dementia, researchers believe that consuming dietary antioxidants can
shield our brains from this damage , as in other diseases. Animal-based
foods lack antioxidant shields and tend to activate free radical produc-
t i o n and cell damage, while plant-based foods , with their abundant an-
tioxidants , tend to prevent such damage. It's the same dietary cause and
effect that we saw with macular degeneration.
Of course, genetics plays a role, and specific genes have been identi-
fied that may increase the risk of cognitive decline. 52 But environmental
factors also playa key role, most probably the dominant one.
In a recent study, it was found that Japanese American men living
in Hawaii had a higher rate of Alzheimer's disease than Japanese living
in Japan. 59 Another study found that native Africans had significantly
lower rates of dementia and Alzheimer's than African Americans in In-
diana. 60 Both of these findings clearly support the idea that environment
plays an important role in cognitive disorders.
Worldwide, the prevalence patterns of cognitive disorders appear to
be similar to other Western diseases. Rates of Alzheimer's are low in less
developed areas. 6 1 A recent study compared Alzheimer's rates to dietary
variables across eleven different countries and found that populations
with a high fat intake and low cereal and grain intake had higher rates
of the disease.62, 63
We seem to be on to something. Clearly, diet has an important voice
in determining how well we think in our later years. But what exactly
is good for us?
With regard to the more mild cognitive impairment condition, recent
research has shown that high vitamin E levels in the blood are related
to less memory 10ss.64 Less memory loss also is associated with higher

220                          THE CHINA STUDY
levels of vitamin C and selenium, both of which reduce free radical ac-
tivity.65 Vitamins E and C are antioxidants found almost exclusively in
plant foods, while selenium is found in both animal- a n d plant-based
foods.
In a study of 260 elderly people aged sixty-five to ninety years, it was
reported that: "A diet with less fat, saturated fat and cholesterol, and
more carbohydrate, fiber, vitamins (especially folate, vitamins C and E
and beta-carotenes) and minerals (iron and zinc) may be advisable not
only to improve the general health of the elderly but also to improve
cognitive function."66 This conclusion advocates plant-based foods and
condemns animal-based foods for optimal brain function. Yet another
study on several hundred older people found that scores on mental tests
were higher among those people who consumed the most vitamin C
and beta-carotene. 67 Other studies have also found that a low level of
vitamin C in the blood is linked to poorer cognitive performance in old
age,68,69 and some have found that B vitamins,69 including beta-caro-
tene,1° are linked to better cognitive function.
The seven studies mentioned above all show that one or more nutri-
ents found almost exclusively in plants are associated with a lower risk
of cognitive decline in old age. Experimental animal studies have not
only confirmed that plant foods are good for the brain, but they show
the mechanisms by which these foods work. 71, 72 Although there are
important variations in some of these study findings-for example, one
study only finds an association for vitamin C, and another only finds
an association for beta-carotene and not vitamin C-we shouldn't miss
the forest by focusing on one or two trees. No study has ever found that
consuming more dietary antioxidants increases memory loss. When as-
sociations are observed, it is always the other way around. Furthermore,
the association appears to be Significant, although more substantial re-
search must be done before we can know exactly how much cognitive
impairment is due to diet.
What about the more serious dementia caused by strokes (vascular
dementia) and Alzheimer's? How does diet affect these diseases? The de-
m e n t i a that is caused by the same vascular problems that lead to stroke
is clearly affected by diet. In a publication from the famous Framingham
Study, researchers conclude that for every three additional servings of
fruits and vegetables a day, the risk of stroke will be reduced by 22%.73
Three servings of fruits and vegetables is less than you might think. The
following examples count as one serving in this study: 112 cup peaches,