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 It's not certain that milk was the reason for the
slower arthritis progression, researchers said, and the effect was
not seen in men. But the results add to evidence that nutrition may
help to stave off arthritis.
"Milk is an excellent source of vitamins and minerals, dairy calcium
and protein and has long been recognized for its important role in
bone health," Dr. Bing Lu told Reuters Health in an email.
Lu, of Brigham and Women's Hospital in Boston, led the study, which
was published in Arthritis Care and Research.
"We therefore hypothesized that milk consumption may prevent
osteoarthritis progression," Lu said.
Arthritis causes pain and swelling of joints in the hand, hips or
knees. According to the Centers for Disease Control and Prevention,
it affects more than one third of Americans over age 65.
For the new study, Lu and colleagues analyzed data from a study
launched in 2002 by the National Institutes of Health and focused
specifically on osteoarthritis of the knee.
A total of 2,148 participants with 3,064 arthritic knees were
involved in the analysis by Lu's team. They included 888 men and
1,260 women, who were all, on average, in their early 60s at the
beginning of the study.
At that point, the participants answered questions about their
diets, including how often they drank any kind of milk during the
previous 12 months and how much they drank.
Because the space between bones in the knee narrows with
deteriorating arthritis, X-rays were used to measure changes in
joint space width in the affected knees. The researchers followed up
with the participants at 12, 24, 36 and 48 months after the initial
examinations and surveys.
Lu's team grouped the participants based on the number of
eight-ounce glasses of milk they drank per week: none, fewer than
three glasses, four to six glasses, and more than seven glasses.
When they compared the changes in joint space width among the
participants over time, they found the width had decreased by 0.38mm
in women who drank no milk at all, by 0.29mm in those who had up to
six glasses of milk a week and by just 0.26mm in those who had more
than seven glasses.
There was no such link between milk consumption and joint space
width changes seen among the men.
"The gender differences in the relationship of milk consumption with
osteoarthritis progression are not completely understood," Lu said,
adding that sex differences have been noted in the prevalence,
incidence and severity of arthritis for many years.
Previous studies have shown that the thickness of cartilage at the
end of the distal femur, or thigh bone, is already smaller in women
compared to men, Lu noted.
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Other evidence also suggests that estrogens from outside sources
may protect cartilage and affect bone turnover, he said.
"If dietary calcium is a possible (factor linking) milk
consumption and knee osteoarthritis progression, women may be more
sensitive for the effect of calcium intake through milk than men,"
Lu said.
Not all dairy was associated with benefits, however. Yogurt
consumption appeared to have no effect on arthritis progression, and
the women who ate more cheese had greater deterioration in their
joint space width.
It's possible that the high levels of saturated fat in cheese may
worsen arthritis progression, Lu said, or it could contribute to
obesity, which would also worsen arthritis.
It's also possible that high milk consumption is merely a sign of an
overall healthy lifestyle, Lu and his colleagues acknowledge out in
their report. When they adjusted for total calcium in the diet, the
effect of milk weakened somewhat.
Although the exact mechanism linking milk consumption and
arthritis is not yet clear, Dr. Cathy Alessi called the study an
interesting and careful analysis.
"Osteoarthritis is extremely common in older people and can cause
significant impairments in their quality of life and in their
well-being," said Alessi, the acting director of the Geriatric
Research, Education and Clinical Center in the VA Greater Los
Angeles Healthcare System.
The two most common things doctors generally recommend for patients
are to maintain a healthy weight and to remain as physically active
as possible, she said.
But there's also growing evidence that nutritional factors beyond
dieting to keep a healthy weight may affect the progression of
arthritis, Alessi added.
"So this study is, I think, more evidence of a possible link between
nutrition and arthritis," she said. ___
Source: http://bit.ly/1qfeAOw
Arthritis Care and Research, online April 7, 2014.
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