Vitamin Information Center

A connection between vitamin D level and the risk of developing breast cancer has been implicated for a long time, but its clinical relevance had not yet been proven. Sascha Abbas and colleagues from the working group headed by Dr. Jenny Chang-Claude at the German Cancer Research Center (Deutsches Krebsforschungszentrum, DKFZ), collaborating with researchers of the University Hospitals in Hamburg-Eppendorf, have now obtained clear results: While previous studies had concentrated chiefly on nutritional vitamin D, the researchers have now investigated the complete vitamin D status. To this end, they studied 25-hydroxyvitamin D (25(OH)D) as a marker for both endogenous vitamin D and vitamin D from food intake.

The result of the study involving 1,394 breast cancer patients and an equal number of healthy women after menopause was surprisingly clear: Women with a very low blood level of 25(OH)D have a considerably increased breast cancer risk. The effect was found to be strongest in women who were not taking hormones for relief of menopausal symptoms. However, the authors note that, in this retrospective study, diagnosis-related factors such as chemotherapy or lack of sunlight after prolonged hospital stays might have contributed to low vitamin levels of breast cancer patients.

In addition, the investigators focused on the vitamin D receptor. The gene of this receptor is found in several variants known as polymorphisms. The research team of the DKFZ and Eppendorf Hospitals investigated the effect of four of these polymorphisms on the risk of developing breast cancer. They found out that carriers of the Taql polymorphism have a slightly increased risk of breast tumors that carry receptors for the female sex hormone estrogen on their surface. No effects on the overall breast cancer risk were found. A possible explanation offered by the authors is that vitamin D can exert its cancer-preventing effect by counteracting the growth-promoting effect of estrogens.

Besides its cancer-preventing influence with effects on cell growth, cell differentiation and programmed cell death (apoptosis), vitamin D regulates, above all, the calcium metabolism in our body. Foods that are particularly rich in vitamin D include seafish (cod liver oil), eggs and dairy products. However, the largest portion of vitamin D is produced by our own body with the aid of sunlight.

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The task of the Deutsches Krebsforschungszentrum in Heidelberg (German Cancer Research Center, DKFZ) is to systematically investigate the mechanisms of cancer development and to identify cancer risk factors. The results of this basic research are expected to lead to new approaches in the prevention, diagnosis and treatment of cancer. The Center is financed to 90 percent by the Federal Ministry of Education and Research and to 10 percent by the State of Baden-Wuerttemberg. It is a member of the Helmholtz Association of National Research Centers (Helmholtz-Gemeinschaft Deutscher Forschungszentren e.V.).

April 11th 2008, Lysaker, Norway - An increased intake of vitamin K2 may reduce the risk of prostate cancer by 35 per cent, suggest results from the European Prospective Investigation into Cancer and Nutrition (EPIC).

The findings, based on dietary intake from 11,319 men taking part in the EPIC Heidelberg cohort, are published in this month’s issue of the American Journal of Clinical Nutrition.

The study, by Katharina Nimptsch, Sabine Rohrmann and Jakob Linseisen, adds to a growing body of science supporting the potential health benefits of vitamin K2, most notable for bone and blood health.

In this recent study, dietary intake of vitamin K2 was linked to an inverse association with prostate cancer, while vitamin K1 intake did not offer any prostate benefits, report the researchers from the German Cancer Research Centre in Heidelberg.

Dr. Anne Bjørnebye Vik, Vice President R&D for NattoPharma, says: “ The potential anti-tumor effect of vitamin K2, in this case specifically prostate cancer, adds to the great potential for NattoPharma’s natural vitamin K2, MenaQ7™, one of the more documented derivatives in the group of vitamin K2’s or the so called long-chain menaquinones. As this interesting field of nutrition and cancer now also include vitamin K2, we are excited that NattoPharma’s natural menaquione-7, branded as MenaQ7™, shows to be the optimal form of vitamin K2.”

The study has also been welcomed by leading vitamin K researcher Cees Vermeer, PhD, from the VitaK and Cardiovascular Research Institute CARIM at the University of Maastricht. Commenting on the research, Dr. Vermeer says: “the beneficial effect of the long-chain menaquinones has previously been reported for cardiovascular disease; this specific form of vitamin K2 is characterized by preferential transport (via LDL) to extra-hepatic tissues (such as prostate and arterial vessel wall), and by very long half-life times (three days versus 1.5 hours) as compared to vitamin K1 and the short-chain menaquinone-4.

“I am highly pleased by this paper, which underpins the (widely underestimated) importance of long chain menaquinones for disease prevention,” Dr. Vermeer says.

“It also supports my opinion that intake of vitamin K2 supplements may have a significant contribution to public health.”

Study details

Nimptsch, Rohrmann and Linseisen from the Division of Cancer Epidemiology at the German Cancer Research Centre state that epidemiologic studies of dietary vitamin K intakes have not been conducted in relation to prostate cancer risk.

According to the European School of Oncology, over half a million new cases of prostate cancer are diagnosed every year worldwide, and the cancer is the direct cause of over 200,000 deaths. More worryingly, the incidence of the disease is increasing with a rise of 1.7 per cent over 15 years.

A food frequency questionnaire was used to assess habitual dietary intakes at the start of the study, with vitamin K intakes divided into phylloquinone (vitamin K1) and menaquinones (vitamin K2) and total and advanced prostate cancer in the Heidelberg cohort of the European Prospective Investigation into Cancer and Nutrition.

The researchers documented 268 incident cases of prostate cancer during the 8.6 years of follow-up. Of these, 113 cases were classified as advanced prostate cancer. While no reduction in the risk of prostate cancer was observed for vitamin K1 (phylloquinone), an increased intake of all menaquinones (vitamin K2) was associated with a 35 per cent reduction in risk. However, the researchers stated that this association was “non-significant”.

Furthermore, a strong association was documented when they considered only advanced prostate cancer, with increased intake of menaquinones linked to a 63 per cent reduction in risk.

While dietary sources of menaquinones include meat and fermented food products like cheese, and natto, Nimptsch and co-workers report that menaquinones from dairy had a stronger inverse association with advanced prostate cancer than did menaquinones from meat.

“Our results suggest an inverse association between the intake of menaquinones, but not that of phylloquinone, and prostate cancer,” concluded the researchers. “Further studies of dietary vitamin K and prostate cancer are warranted.”

Source: American Journal of Clinical Nutrition
April 2008, Volume 87, Number 4, Pages 985-992
“Dietary intake of vitamin K and risk of prostate cancer in the Heidelberg cohort of the European Prospective Investigation into Cancer and Nutrition (EPIC-Heidelberg)”
Authors: K. Nimptsch, S. Rohrmann, J. Linseisen
NattoPharma, Norway offers a natural vitamin K2 under the trade name MenaQ7.

K definitions

There are two main forms of vitamin K: phylloquinone, also known as phytonadione, (vitamin K1) and menaquinones (vitamins K2). K1 is found in green leafy vegetables such as lettuce, broccoli and spinach, and makes up about 90 per cent of the vitamin K in a typical Western diet; while K2, which makes up about 10 per cent of Western vitamin K consumption, is found mainly in fermented dairy products as e.g. cheese. The Japanese food Natto (fermented soybeans) is especially rich in vitamin K2.

A synthetic form of vitamin K, known as K3, does exist but is not recommended for human consumption.

The vitamin K’s are less well known than vitamins A to E, but this increasing body of research, as well as increased marketing and advertising from supplement makers, is raising public awareness of vitamin K.