By Prof W J Serfontein
Vitamin D deficiency is far more common than previously thought, and the health consequences of such a deficiency reach beyond the role that the vitamin plays in calcium (mineral) absorption. This deficiency can negatively affect the growth of cells in the many organs with vitamin D receptors, as well as bones and teeth.
Studies have revealed the presence of vitamin D deficiency in cases of rickets, osteomalacia and osteoporosis, and recent research suggests that it may, in conjunction with inadequate levels of vitamin K, be a factor in cancer, heart disease and many other conditions.
Vitamin D deficiency may be caused by decreased exposure to the sun (as would be the case for inhabitants in the Northern Hemisphere) and impaired absorption mechanisms. During exposure to the sun`s ultraviolet rays, a significant amount of vitamin D is formed in the skin (Vitamin D Council Website).
Full-body exposure to the sun for a single, twenty-minute period will trigger the formation of 500 mcg (20 000 IU) of vitamin D in the circulation of most people within 48 hours. This suggests that the widely prescribed intake levels are inadequate (for example, the Food and Nutrition Board`s defined upper limit of 2 000 IU (500 mcg) of vitamin D may be too low).
Currently, many authorities believe that the daily physiological requirement for adult humans may be as high as 5 000 IU (125 mcg) of vitamin D, which is considerably lower than the amount endogenously produced by the aforementioned full-body sun exposure (Am J Clin Nutr, 1999, 69:842 and 2003, 77:204).
Vitamin K frequently assists vitamin D in the role it plays in many diseases other than those which are bone-related. Vitamin D receptors have been discovered in a variety of tissues other than bone, including the cells of the brain, breast, prostate, and immune system.
Recent research suggests that higher vitamin D levels, in association with sufficient levels of vitamin K, may protect against cardiovascular disease, metabolic syndrome, diabetes, osteoporosis, autoimmune diseases and cancers of the breasts, colon, and prostate.
The latest knowledge regarding vitamin D enables its use for a wider range of preventative and therapeutic applications to maintain and improve health.
Vitamin K’s role in the prevention of cancer and heart disease is of particular interest.
Scientists at the University of California wrote a review report of 63 published papers addressing the relationship between cancer incidence and vitamin D nutritional status (Knowledge of Health website). The review revealed that cancer rates can be drastically reduced by raising blood levels of vitamin K (beyond dietary levels) through supplementation.
This may be of particular interest to those living in regions where sun exposure is limited and is especially true for people with darker complexions who are immigrating to such regions.
The relationships between vitamin D and the formation of bone, heart health, and calcium metabolism are noteworthy because of the simultaneous involvement of other nutrients, most notably vitamin K.
Vitamin D is needed for the absorption of calcium (and several other minerals), but after this has taken place and when calcium appears in the blood, the fate of this calcium is determined by the presence or absence of vitamin K. In this manner vitamin K may protect against heart disease and osteoporosis.
Nearly 100 years ago, a German pathologist named Monckeberg noticed that the middle layers (tunica media) of the arteries of patients who had died of heart attacks were severely calcified. The tunica media contains the muscular structures which impart pliability to the arteries, allowing them to expand and contract during the heartbeat. A hardened or calcified artery loses its muscle tone and cannot contract and expand during the heartbeat, increasing the chances of a heart attack (Virchows Arch A, 1903, 171:141).
This condition later became known as ‘arteriosclerosis’ as opposed to ‘atherosclerosis’; a condition also associated with heart disease, but which results from damage to the inner arterial layer (tunica intima).
Arteriosclerosis is a result of calcification of the arteries and is a phenomenon associated with ageing. The Framingham study showed that sudden death is 7 times more common in patients with calcified arteries.
Scientists in Japan were the first to show that the calcification of arteries can be drastically reduced in rats through the administration of vitamin K – the level of calcium in the arteries of the animals that had not received vitamin K was 17 times higher.
The fate of calcium in the blood is thus determined by the absence or presence of vitamin K. In the presence of adequate levels of vitamin K, calcium follows its normal route to the bones, preventing conditions such as osteoporosis. However, arteries calcify with age, while bone decalcifies. Bad bones and bad arteries are serious human conditions, the treatments for which millions of dollars are spent annually.
Both processes occur simultaneously in most people, and the extent to which calcium goes to the arteries instead of to the bones is determined by the vitamin K status of the patient (Atherosclerosis, 1997, 132:61).
Administering calcium and other minerals to patients with osteoporosis addresses only one aspect of the problem – although it supplies a sufficient amount of minerals, it does not ensure that calcium is directed to the correct tissues.
In this regard, vitamin K makes use of carboxylation (addition of a carboxyl group) of an amino acid called gamma carboxyglutamic acid.
The glutamic acid molecule acquires additional ‘claws’ that allow it to bind calcium and carry it to the bones. The glutamic acid molecules occur in nature as part of the calcium-carrying proteins (many of which are known) that need vitamin K to function as indicated.
The Framingham study showed that 35-year-old men with calcifications of the aorta were 7 times more likely to die of a heart attack. A similar increase was demonstrated in other risk groups (Am J Cardiol, 1990, 66:1060). These studies show that calcification of the arteries and fat accumulation in the arteries are equally likely to cause heart disease. In repeat experiments, it was shown that the incidence of arterial calcification and heart attacks was substantially reduced in animals pre-treated with vitamin K.
These experiments have shown that under-carboxylated glutamic acid cannot control the deposition of calcium in the bones and, under these conditions, part of the available calcium may be redirected to the arteries and cause heart attacks and other health problems.
Osteocalcin is one of the better-known carboxylated glutamic acids correlated with bone density. Under-carboxylated osteocalcin (osteocalcin formed in the presence of low levels of vitamin K) cannot regulate calcium tissue access in the way it is usually directed towards the bones, causing the calcium to move from the bones and teeth towards the arteries. It was found that women with under-carboxylated osteocalcin excrete increased quantities of calcium in their urine (J Vit Nutr Res, 1999, 69:23).
In addition to enabling calcium absorption, vitamin D promotes the activity of the osteocalcin gene – once synthesised, osteocalcin needs vitamin K to function properly. Both vitamins are needed for optimal bone function, although vitamin K is much more slow-acting (which is likely why it has escaped attention in the past).
Bone maintenance requires several additional factors, including parathyroid hormone, estrogen and calcitonin. These are usually not in short supply – at least not to such an extent that bone maintenance may be compromised. When all these factors are present in adequate amounts, the skeleton will be renewed every 8 – 10 years.
This process slows in old age. Vitamins D and K appear to be of special significance to the elderly, for whom osteoporosis and bone fractures often cause serious problems.
In one major study (known as ‘The Nurses’ Health Study’) spanning 10 years, it was concluded that of the 72 000 nurses studied, those who got the most vitamin K were about 30% less likely to get hip fractures.
Lettuce is a significant dietary source of vitamin K, and the nurses who ate lettuce every day reduced their hip-fracture risk by 50% more than those who only ate lettuce once a week. In this study, the effect of vitamin K on reducing osteoporotic fractures proved greater than that of estrogen, which did not significantly protect the participants bone density.
It was also found that vitamin D alone did not effectively protect bone density – women who took high doses of vitamin D but insufficient doses of vitamin K doubled their risk of hip fractures.
Other studies have shown that vitamin K has a significant effect on bone loss in a post-menopausal population. This observation was confirmed by an independent study in the Netherlands, which showed that 1 mg of vitamin K taken every day for a period of 14 days increased the level of carboxylated glutamic acid by 70-80% in post-menopausal women – attaining the same level as in pre-menopausal women – and yet another study showed that vitamin K reduced urinary calcium loss by one third in women with a tendency to lose calcium.
Bone density and mortality risk
Osteoporosis may be a sign of other serious health problems. The Study of Osteoporotic Fractures (Arch of Int Med, 1999, 159:1215) revealed that bone density is an unexpectedly strong predictor of death and that every standard deviation from normal bone density was associated with a 20% increased risk of death in women aged 65 and older.
For example, while 46 deaths occurred in the group of people with the highest bone density, 78 deaths occurred in the group with the lowest bone density.
Quite unexpectedly, osteoporosis (and the broken bones and complications associated with it) was not the primary cause of death for the women suffering from it. Falling accounted for only 3% of deaths in this osteoporosis study, with the majority of deaths resulting from heart attacks, cancer and stroke.
It was concluded that calcium (which was supposed to be in the bones) was relocated to the arteries, as discussed above. The study found that women who had one or more back fractures had a 23% increased risk of dying and that severe kyphosis increased the risk of dying from a lung-related disorder (a blood clot, for example) by as much as 260%.
Vitamin K and stroke
A stroke is primarily caused by the same bad blood vessels that are responsible for heart disease. Studies on the underlying causes of stroke have, in the past, often centred on dietary salt as a regulator of blood pressure.
A review of 58 studies recently published concludes that the survey does not support the general recommendation to reduce sodium intake (Arch Int Med, 1999, 159:285). This was supported by Dr MacCarron’s finding that calcium plays a primary role in determining blood pressure one standard deviation from the norm of bone density is associated with a 300% increased risk of stroke and a 170% increased risk of high blood pressure.
The question of whether vitamin K may be involved was raised when it was found that vitamin supplements prevented the thickening of arteries in stroke-prone rats.
A recent report from the “Dietary Approaches to Stop Hypertension” (DASH) study indicates that one’s salt intake and body weight do not affect one’s blood pressure but eating fruits and vegetables does. This once again draws attention to the calcium-regulating vitamin K, of which dietary fruits and vegetables are an important dietary source.
Although more specific studies are required, the above studies collectively indicate that vitamin K levels may be an important factor in determining blood pressure, thereby allowing one to reduce the incidence of stroke and bring order to the multitude of confusing and conflicting studies which have attempted to define the true causes of hypertension and strokes.
Vitamin K stressors
The following are some aspects of the modern diet that may suppress the bioavailability of vitamin K:
- Cholesterol-reducing drugs: Our past misplaced obsession with blood-cholesterol levels, which resulted in the indiscriminate use of cholesterol-lowering drugs.
- Antibiotics: Vitamin k-producing intestinal bacteria, which are an important source of vitamin K2, are destroyed by antibiotics.
- Unwarranted dietary restrictions, slimming diets, and low-fat diets: These contribute to the reduced bioavailability of vitamin K. It is important to note that it is the oil in one’s salad dressing that enables absorption of the vitamin K in one’s green salad.
Vitamin K: sources and dosage levels
Green, leafy vegetables supply about 40-50% of vitamin K for most Americans, with vegetable oils being the next-highest source.
Hydrogenated oils such as margarine contain an unnatural form of the vitamin which antagonises the action of natural vitamin K.
There are 3 different forms of vitamin K: K1 from plants, K2 from bacteria, and the synthetic, less-desirable K3. K2 appears to be the preferred form because it specifically keeps calcium out of the arteries, and the body converts K1 into K2.
Vitamin K in the form of K1 and K2 is not toxic (even in high doses) and, unlike other fat-soluble vitamins, does not accumulate in the body.
High amounts of the vitamin will also not cause the blood to over coagulate – once the coagulation proteins have been saturated with the vitamin, further increases of vitamin K will not affect (Life Extension, 2000, p38).
Dosage levels of up to 45 mg a day have been used in osteoporosis studies in Japan, but no final recommendations are available because individual requirements are determined by diet, age and the presence of stressors. Generally, a dosage level of 10 mg per day is recommended.
Patients who take blood thinners such as Coumadin should not take vitamin K without consulting their doctor.
Fortifood’s product “Vitamin D3 & K2” contains Vitamin D3, Vitamin K2 as well as beta carotene. For more information please contact them at 012 811 0432 (mornings only), or visit their website at www.fortifood.co.za