The more vitamin K [structural formula on the right] you consume through your diet, the less likely you are to die from a heart attack or cancer. Spanish epidemiologists made this discovery after following 7216 people over the age of 55 for five years. The researchers believe that raising your vitamin K intake is one of the more sensible things you can do to extend your lifespan.
Vitamin K is not just one substance, but a group of compounds that can be divided roughly speaking into two subgroups: vitamin K1 – aka phylloquinone – and vitamin K2 – aka menaquinone. Vitamin K1 is found in vegetables, in particular curly kale and spinach; vitamin K2 is found mainly in fermented foods such as cheese, quark, yoghurt and natto.
The body needs vitamin K for the enzyme gamma-glutamyl-carboxylase to be able to do its work. This enzyme is involved in bone building, but also in keeping the walls of the blood vessels supple. Epidemiologists have reported that people who consume large amounts of vitamin K2 are less likely to develop cardiovascular disease. [Nutr Metab Cardiovasc Dis. 2009 Sep;19(7):504-10.]
Vitamin K is also involved in the process of blood coagulation. Anti-coagulant medicines often work by deactivating vitamin K.
In addition, vitamin K appears to inhibit cancer cells. A high vitamin K2 intake also reduced the chance of prostate cancer by almost half in the EPIC studies [Am J Clin Nutr. 2008 Apr;87(4):985-92.], and also reduced the chance of dying from cancer generally. [Am J Clin Nutr. 2010 May;91(5):1348-58.]
Study
In their article in the Journal of Nutrition the Spaniards also write that their study – which involved 7216 over 55s at risk from cardiovascular disease – showed that vitamin K protects against cardiovascular disease. The researchers divided their participants into four groups, based on their vitamin K1 and K2 intake and observed that mortality was lower in the group with the highest intake [Q4] than in the other groups.
The correlation was strongest with the K1 intake [below left], but there was also a correlation, albeit less strong, with vitamin K2 [below].
When the researchers had corrected for everything they could think of – including vegetable intake – they discovered that a high vitamin K2 intake [in Q4 the average intake was 57.5 mcg/day] reduced the likelihood of dying from cancer, but that the reduction was not statistically significant. Vitamin K2 had no effect on total mortality risk.
The protective effect of vitamin K1 was more convincing. A high vitamin K1 intake [in Q4 the average intake was 626.4 mcg/day] reduced the risk of dying from cancer, and the effect was statistically significant.
The reduction in the likelihood of developing cardiovascular disease as a result of a high vitamin K1 intake was not significant, but the effect on total mortality risk was.
The researchers looked at the effect of changes in vitamin K intake. The table below shows that an increase in both vitamin K1 and K2 intake almost halved all-cause mortality.
Conclusion
“Our results suggest that the dietary intake of both active forms of vitamin K has a potential protective role in cardiovascular mortality, cancer mortality, and all-cause mortality in a cohort of Mediterranean individuals at high cardiovascular disease risk with a relatively high consumption of this vitamin”, the researchers conclude.
Dietary intake of vitamin K is inversely associated with mortality risk.
Abstract
Vitamin K has been related to cardiovascular disease and cancer risk. However, data on total mortality are scarce. The aim of the present study was to assess the association between the dietary intake of different types of vitamin K and mortality in a Mediterranean population at high cardiovascular disease risk. A prospective cohort analysis was conducted in 7216 participants from the PREDIMED (Prevención con Dieta Mediterránea) study (median follow-up of 4.8 y). Energy and nutrient intakes were evaluated using a validated 137-item food frequency questionnaire. Dietary vitamin K intake was calculated annually using the USDA food composition database and other published sources. Deaths were ascertained by an end-point adjudication committee unaware of the dietary habits of participants after they had reviewed medical records and linked up to the National Death Index. Cox proportional hazard models were fitted to assess the RR of mortality. Energy-adjusted baseline dietary phylloquinone intake was inversely associated with a significantly reduced risk of cancer and all-cause mortality after controlling for potential confounders (HR: 0.54; 95% CI: 0.30, 0.96; and HR: 0.64; 95% CI: 0.45, 0.90, respectively). In longitudinal assessments, individuals who increased their intake of phylloquinone or menaquinone during follow-up had a lower risk of cancer (HR: 0.64; 95% CI: 0.43, 0.95; and HR: 0.41; 95% CI: 0.26, 0.64, respectively) and all-cause mortality (HR: 0.57; 95% CI: 0.44, 0.73; and HR: 0.55; 95% CI: 0.42, 0.73, respectively) than individuals who decreased or did not change their intake. Also, individuals who increased their intake of dietary phylloquinone had a lower risk of cardiovascular mortality risk (HR: 0.52; 95% CI: 0.31, 0.86). However, no association between changes in menaquinone intake and cardiovascular mortality was observed (HR: 0.76; 95% CI: 0.44, 1.29). An increase in dietary intake of vitamin K is associated with a reduced risk of cardiovascular, cancer, or all-cause mortality in a Mediterranean population at high cardiovascular disease risk. This trial was registered at http://www.controlled-trials.com as ISRCTN35739639.
PMID: 24647393 DOI: 10.3945/jn.113.187740 [Indexed for MEDLINE]
