A new study has once again indicated that lower blood levels of vitamin D, specifically 25(OH)D3, is a major risk factor for early death.
This study, along with others, further establishes the link. But is it just a matter of everyone supplementing with D3 to extend their lifespan? Of course not. It is much more complex than that.
Let me give you another famous blood marker, HDL-cholesterol. The “good” cholesterol is associated with a reduced risk of heart disease, cancer, and early death. The higher the number, generally greater than 60 mg/dl, the better. But it is not that simple…
Have you heard of the “Limone gene?” It is named after inhabitants of Limone sul Garda, a small village of 1,000 inhabitants in northern Italy between Milan and Venice. The Limonese live longer, do not have heart disease, and seemingly have discovered the “fountain of youth.”
Scientists have been studying these people for over 40 years trying to find their secret. They sought to understand if it was their diet, lifestyle, unique climate, social network, or some other factor. They were very perplexed because their HDL levels were extremely low, typically in the 7-15 mg/dl range versus the normal range of above 40 mg/dl and well below the higher optimal levels.
Well, it turns out they have a special form of HDL that contains a mutated protein known as Apolipoprotein A-1 Milano, that can be traced back to an altered gene from a Limonese couple who married in 1644.
While low HDL in most people carry a poor prognosis, in the Limonese, their form is so powerful in its protective effects it is associated with robust health and longevity.
O.K., what does this story of the Limone gene have to do with blood levels of vitamin D3 and mortality? I will get to that answer, but let me share the results of this recent study...
Researchers in Australia used a very complex approach in analyzing the relationship between 25(OH)D3 levels and mortality. They were able to look at people with very low vitamin D blood levels, less than 20 ng/ml (50 nmol/l) and determine mortality rates in over 36,000 participants.
The result was that the risk for mortality was 36% higher for participants with low levels of 25(OH)D3, i.e., less than 20 ng/ml. And those with the lowest levels of 25(OH)D3 were found to have a 6-fold increased risk for death due to heart disease, a 3-fold increased risk for cancer mortality, and an over 12-fold risk for dying from a respiratory condition.
These results are consistent with population-based studies. Now, let me provide some practical guidelines. First, the key with D3 is to supplement at a daily dosage that will produce a blood level of 50–80 ng/ml. And the only way to know what that dosage is exactly is through testing.
The recommendation from vitamin D3 experts from around the world is that for adults currently not taking vitamin D3 or those with 25(OH)D3 blood levels of less than 30 ng/ml should take 10,000 IU (250 mcg) daily for 2–3 weeks. After this loading dosage, adults should supplement at a dosage of 4,000-5,000 IU (100-125 mcg) daily. This dosage is universally regarded as safe.
O.K, now let me explain the link between the Limone gene and these vitamin D3 studies. If we simply looked at HDL levels in the Limonese, we would conclude that very low HDL levels were the key to a longer, healthier life.
And if we look at only 25(OH)D3 blood levels and longevity studies, we might be making a similar mistake. There are other factors to consider.
For example, I often get asked why do many people have low 25(OH)D3 blood levels despite adequate sun exposure or supplementation?
After vitamin D3 is produced in the skin or acquired from food or supplements, it is delivered to the liver to form 25(OH)D3. That is what is measured to reflect vitamin D status.
And what do we know about liver function and 25(OH)D3? The obvious! Poor liver function leads to low levels of 25(OH)D3.
Liver issues, including the common liver issue that occurs in people who have type 2 diabetes and/or obesity (non-alcoholic fatty liver or NAFLD), can lead to lower blood levels of 25(OH)D3, even if the intake of vitamin D3 is sufficient. The reason is because of impaired conversion of D3 by the liver to 25(OH)D3.
Given the epidemic of obesity and type 2 diabetes in many parts of the world, it is little wonder that blood levels of 25(OH)D3 are low and carry with it an increased risk of early death.
Interestingly, vitamin D3 supplementation has been shown to greatly improve NAFLD, which leads to a chicken or the egg question, i.e., does NAFLD develop due to low 25(OH)D3 levels?
Here is the bottom line to all the above. Our health is a complex system of interdependent and interrelated factors. We certainly need to have optimal levels of 25(OH)D3, but it is only one star in the constellation of health.
In good health,
Dr. Michael Murray