For decades, science has had its focus on vitamin D in terms of cancer prevention. A new study shows that this applies particularly to women older than 55 years. It may be because cancer often takes many years to develop and because our ability to utilize the vitamin decreases as we grow older.
More and more people contract cancer and die of the disease, and this is a frightening development. However, a recent study from the UC San Diego School of Medicine suggests that vitamin D may be particularly useful for middle-aged and older women. Apparently, they can lower their risk of developing cancer by as much as 67% by making sure to maintain vitamin D blood levels of 40 ng/ml of blood or higher, compared with women whose blood levels of vitamin D are 20 ng/ml or less.
The sun must sit sufficiently high in the sky
Sunlight is by far our most important source of vitamin D. At our latitudes, however, we are only able to synthesize vitamin D during the summer period where the sun sits sufficiently high in the sky. In fact, it is well established that people who live in the northern part of the world easily become vitamin D deficient, especially during the winter time.
35 years ago, Professor Cedric Garland from the Moores Cancer Center, and his brother Frank Garland, pointed to a relation between less sun exposure and increased mortality from colorectal cancer, and they linked it to lack of vitamin D. Later, they conducted studies that looked at the relation between vitamin D deficiency and the risk of other cancer types such as breast cancer and prostate cancer.
The body's ability to activate vitamin D decreases with age
When the sunlight reacts with cholesterol in our skin it produces a precursor of vitamin D. From that point on, our ability to utilize the vitamin depends on various factors. First of all, vitamin D must get converted into 25-hydroxyvitamin D3 in the liver. Afterwards, it gets converted to an active form in the kidneys. People with reduced liver and kidney function may impair the utilization of vitamin D. It also turns out that we humans gradually lose our ability to utilize the vitamin as we grow older. Even if you get plenty of sunlight you can easily have too little active vitamin D in your body on that account.
Far less cancer among women with high vitamin D levels
Vitamin D's cancer protective effect has been known for decades. In the new study, Cedric Garland and his team of researchers wanted to look at how much vitamin D we need to prevent cancer. The scientists started by scrutinizing two older separate cohort studies. One study included 1,169 women aged 55 years and older. The other study included 1,135 women in the same age group. By analyzing data from the two studies and looking at vitamin D status over a four-year period, the researchers soon discovered that there was a much lower incidence of cancer among women with higher blood levels of vitamin D. After adjusting for confounding factors such as smoking and age, the scientists discovered that women with vitamin D levels higher than 40 ng/ml had a 67% lower risk of developing cancer, compared with women whose levels were 20 ng/ml or lower.
Prevention is more important than early diagnosis and treatment
Because the study only includes older women the results cannot be extrapolated to other population groups. Nonetheless, Garland and his team of scientists intend to conduct more studies to uncover the full cancer preventive potential of vitamin D. The scientists say that is more important to prevent cancer and break the globally increasing cancer curve, rather than focus on one-sided early diagnoses and expensive treatments. According to the new study, vitamin D may be a highly useful tool for prevention that can save millions of lives globally and spare people from grueling and often hopeless therapies.
Did you know that the number of Europeans that die of cancer is the equivalent of four jumbo jets filled with passengers crashing on the ground every single day?
Why do we lack vitamin D?
Vitamin D deficiencies have become increasingly common over the last decades due to factors such as too much time spent indoors, fear of the sun, fear of fat, the exaggerated use of sun screen, and long-term consumption of cholesterol-lowering medicine (statins). Also, overweight and older people, plus dark-skinned individuals have difficulty with synthesizing vitamin D.
New threshold levels require supplements during the winter period
When looking at blood levels of vitamin D in the form of 25-hydroxyvitamin D3, the official threshold levels are 50 ng/ml. Still, leading experts believe this level is insufficient and claim that it takes as much as 75-100 ng/ml of vitamin D to obtain optimal protection against disease. Because it is technically impossible for us to produce vitamin D during the winter period, and because our diets only provide very limited amounts of the nutrient, high-dosed vitamin D supplements are recommended during the winter in order to reach optimal blood levels.
Vitamin D, supplements, and absorption
Vitamin D is a lipid-soluble vitamin. Therefore, we humans get the best effect from supplements with vitamin D in capsules with some kind of oil.
Because cancer takes years to develop, it is a good idea to make sure to get enough vitamin D all through life as part of a long-term plan for prevention.
Susan Scutti: High Blood Levels Of Vitamin D Help Protect Women Over 50 From Cancer: Study
Sharon L. McDonnel, Cedric F Garland et al: Serum 25-Hydroxyvitamin D Concentrations ?40 ng/ml Are Associated with >65% Lower Cancer Risk: Pooled Analysis of Randomized Trial and Prospective Cohort Study
Plos One: 2016
Biokemisk Forening: D-vitaminbehov og mangel i Danmark 2009
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