MARCH 2008

THOUGH NOT AS WELL-KNOWN as other members of the vitamin alphabet, vitamin K could prove to be a weapon against the inflammation associated with chronic diseases such as osteoporosis and cardiovascular disease. In a new study published in the American Journal of Epidemiology, Tufts researchers linked high blood levels and dietary intakes of vitamin K with decreased levels of 14 inflammatory markers. The researchers studied phylloquinone, also known as vitamin K1, the most common form of the vitamin, which is found in green leafy vegetables.

“Our findings provide one potential alternative mechanism for a putative protective effect of vitamin K in the progression of cardiovascular disease and osteoporosis, since both diseases are characterized by inflammation,” noted lead author Kyla Shea, PhD, of the Vitamin K Laboratory at Tufts’ Jean Mayer Human Nutrition Research Center on Aging (HNRCA). Chronic inflammation, where the body’s natural protective mechanisms over-react or go out of control, has been associated with a range of conditions that also include arthritis, type-2 diabetes, Alzheimer’s disease and cognitive decline.

Previous research led by Sarah Booth, PhD, director of the Vitamin K Laboratory, has connected higher blood levels of phylloquinone with lower risk of osteoarthritis in the hand and knee and high dietary intake with reduced heart-disease risk in women.

The latest research relied on data from 1,381 participants in the Framingham Offspring Study, who averaged 59 years old. The Tufts scientists measured blood levels of vitamin K1 as well as dietary intake, and related these to 14 different biological markers (biomarkers) of inflammation.

The study also looked for relationships between vitamin D status and inflammation. While some links were found, overall the results on vitamin D were inconsistent.

The mechanism by which vitamin K1 might combat inflammation isn’t known, the researchers said, adding that further research was warranted. Vitamin K1 is a marker for a healthy diet, so this study may also indicate that other compounds also found in a healthy diet may be the factors that reduce inflammation.

Are you getting enough vitamin K to benefit from its anti-inflammatory powers? Probably not. In a recent review of studies on vitamin K status among the elderly, Booth reported that although older adults seem to consume more vitamin K than younger adults, many seniors still aren’t getting the recommended daily amount. Vitamin K is found in leafy greens such as spinach and lettuce as well as in kale, cabbage, cauliflower, broccoli, Brussels sprouts, cereals, milk and soybeans. The recommended daily amount is 90 micrograms for adult females and 120 micrograms for adult males.

TO LEARN MORE: American Journal of Epidemiology, online ahead of print; abstract at aje.oxfordjournals. org/cgi/content/abstract/kwm306v1.