How much Vitamin D can one safely consume?

Two unconnected and recently released studies linked the vitamin to an unhealthy heart and depression-related syndromes.

While a high dose of the vitamin (also known as the sunshine vitamin) is believed to reverse the cardiovascular benefits of Vitamin D, lower levels have been suspected of triggering depression.

The level of Vitamin D in the body is an accepted indicator of the probability of contracting autoimmune diseases, heart and vascular disease, infectious diseases, osteoporosis, obesity, diabetes, certain cancers and neurological disorders such as Alzheimer's and Parkinson's diseases, multiple sclerosis.

On the other hand, an excess of these levels could be dangerous, according to scientists at the Johns Hopkins University School of Medicine

High Vitamin Levels Can Curb Heart health

While a balanced amount is essential for maintaining a healthy heart, new research indicates that an excess could overrule the cardiovascular benefits.

The research, released on Jan. 4, suggests that Vitamin D (effective for good bone health and protection of the heart), could cease being useful as a cardio-protective agent and may even cause harm, as levels in the blood rise above the low-end of what is considered normal.

The findings were published in the Jan. 15 issue of the American Journal of Cardiology. The lead author, Muhammad Amer, said his findings showed that increasing levels of the vitamin in the blood were linked with lower levels of a popular marker for cardiovascular inflammation called c-reactive protein and known as CRP.

The inflammation that was curtailed by vitamin D does not appear to be curtailed at higher levels of vitamin D, said Amer.  Clearly vitamin D is important for your heart health, especially if you have low blood levels of vitamin D. It reduces cardiovascular inflammation and atherosclerosis, and may reduce mortality, but it appears that at some point it can be too much of a good thing, he added.

In fact, Amer warns consumers to be cautious before taking supplements and asks that physicians realize the potential risks involved while prescribing them.

Unfortunately, because Vitamin D is primarily found in the Sun and is not easily obtained through dietary prescriptions, commercially-sold milk has had to be fortified with the Vitamin. Amer, in his findings, noted that people who spent more time indoors and used sunscreen were at greater risks of having lower-than-required levels of the vitamin.

This has led to doctors prescribing supplements and consumers self-medicating themselves otherwise. Apparently, older women often take large doses to fight osteoporosis.

Each 100 international unit of vitamin D ingested daily produces about a one nanogram per milliliter increase 25-Hydroxyvitamin D levels in the blood. People taking vitamin D supplements need to be sure the supplements are necessary. Those pills could have unforeseen consequences to health even if they are not technically toxic, Amer added.

Amer and his colleague, Rehan Qayyum, examined data from more than 15,000 adult participants (a nationally representative sample), in the continuous National Health and Nutrition Examination Survey from 2001 to 2006. They found an inverse relationship between Vitamin D and CRP in adults without cardiovascular symptoms but with relatively low levels.

Low Vitamin D and Depression

American researchers, working out of the University of Texas' Southwestern Medical Center and the Cooper Longitudinal Study in Dallas, suggest there is a possibility of depression setting in for patients with lower levels of Vitamin D. The findings, published in Mayo Clinic Proceedings, suggest screening for Vitamin D levels in patients with a history of depression.

The study attempted to clarify earlier reviews that presented conflicting results linking the deficiency levels of the vitamin to depression. The researchers noted that one out of every ten adults in the U.S. suffered from depression and that the vitamin had already been associated with a host of health woes, from cardiovascular diseases to neurological ailments.

Our findings suggest that screening for vitamin D levels in depressed patients - and perhaps screening for depression in people with low vitamin D levels - might be useful, said Dr. E. Sherwood Brown, a professor of psychiatry and lead author of the study.

But we don't have enough information yet to recommend going out and taking supplements, he added.

Brown explained researchers had yet to determine the exact relationship between decreased levels of the vitamin and symptoms of depression or, indeed, whether depression itself contributed to lower Vitamin D levels or other chemical parameters.  

However, he did note that the vitamin could affect neurotransmitters, inflammatory markers and other factors, which could help explain the relationship with depression.

The researchers examined the results of tests on almost 12,600 participants, from late 2006 to late 2010. Furthermore, the investigators also used information gathered by the Cooper Institute, which has 40 years of data.

The partnership between the University of Texas and the institute - a preventive medicine research and educational non-profit organization located at the Cooper Aerobics Center - has developed a joint scientific medical research program, aimed at improving health and preventing a wide range of chronic diseases.