There are two different forms of vitamin K, vitamin-K1 & K2 (respectively called phylloquinone and menaquinone). Vitamin-K1 is present in high quantities in collard & turnip greens, broccoli, spinach and some other green leafy vegetables with lower amounts in some other foods such as kiwifruits and dried prunes etc. Vitamin-K2 comes in several subtypes which are generally found in fermented foods.

Ever-increasing evidence indicates that vitamin-K1 and vitamin-K2 clearly have different roles in the body

Vitamin-K1 is vital for both producing blood clots to stop blood loss from a cut, as well as for stopping of excess or inappropriate blood-clotting. For example, when unwanted clotting occurs in the blood stream of a person, the clot could lodge in the veins of the leg, or in the arteries of the lungs or heart, leading to DVTs, pulmonary embolism or heart attack respectively. Vitamin K1 helps ensure these do not occur.

Viitamin-K2 (MK4) can be synthesized from vitamin-K1 in the brain, liver, and pancreas. Nevertheless, food scientists are urging that vitamin-K2 be given its own recommended daily intake (RDI), i.e., separate from that for vitamin-K1.

‘Vitamin K2 has been shown to play a role in improving outcomes for osteoporosis, atherosclerosis, cancer, and inflammatory diseases.

Natto, the world’s richest source of vitamin-K2 has been eaten in ‘Northern Japanese cuisine, for over 1000 years (30 generations) without any adverse side-effects. High intake of Vitamin-K2-rich natto is also postulated as ‘the reason that Japan has a lower fracture risk and Japanese have better bone density and strength than other people in other countries. Even within Japan, the higher the natto consumption the lower the age-related bone loss.

Supplemented vitamin-K2 is also very safe. In Japan doctors regularly prescribe 45 mg/day (15 mg MK-4 three-times-a-day) of vitamin-K2 to osteoporotic women.

Worldwide many patients have participated in vitamin-K2 trials, using doses from as low as 10 μg up to 45 mg/day for several years with no adverse side effects reported. Studies show that vitamin-K2 can be supplemented at doses as high as 135 mg per day with no adverse side effects [46 ].

A recent study in Japanese postmenopausal women showed that even doses as low as 350 μg MK-7 per week significantly reduced osteoporotic fractures risk.

Vitamin-K2 deficiency is well established in haemodialysis patients and implicated as the factor linking the high rate of vascular calcification, bone mineral density loss , and fracture rate of these patients. Vitamin K2 supplementation studies also suggests potential benefit for cardiovascular disease, type II diabetes and for patients with chronic kidney disease.

From a clinical-nutrition perspective, it’s generally more beneficial to eat foods rich in vitamin-K1 or K2 rather than supplement. Why? Foods allow a person to cover multiple bases. For example, bone-loss-rate is dependent on vitamin-K2 intake, and protein intake (amongst many other factors). When a person eats natto, they’ll get excellent, highly bio-available levels of protein, vitamin-K2, together with many other bone-healthy factors, in the one food.

Article Written + Submitted by:

Andreas Klein Nutritionist + Remedial Therapist from Beautiful Health + Wellness
P: 0418 166 269