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supplements

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With vitamin D supplementation, more is not necessarily better.

By David Dunaief, M.D.

Dr. David Dunaief

Here in the Northeast, we are quickly approaching the point in the year when we have the least daylight hours. This is the point at which many reach for vitamin D, one of the most important supplements, to compensate for a lack of vitamin D from the sun. Let’s explore what we know about vitamin D supplementation.

There is no question that, if you have low levels of vitamin D, replacing it is important. Previous studies have shown that it may be effective in a wide swath of chronic diseases, both in prevention and as part of the treatment paradigm. However, many questions remain. As more data come in, their meaning for vitamin D becomes murkier. For instance, is the sun the best source of vitamin D?

At the 70th annual American Academy of Dermatology meeting in 2012, Dr. Richard Gallo, who was involved with the Institute of Medicine recommendations, spoke about how, in most geographic locations, sun exposure will not correct vitamin D deficiencies. Interestingly, he emphasized getting more vitamin D from nutrition. Dietary sources include cold-water fatty fish, such as salmon, sardines and tuna.

We know its importance for bone health, but as of yet, we only have encouraging — but not yet definitive — data for other diseases. These include cardiovascular and autoimmune diseases and cancer.

There is no consensus on the ideal blood level for vitamin D. For adults, the Institute of Medicine recommends between 20 ng/ml and 50 ng/ml, and The Endocrine Society recommends at least 30 ng/ml.

Cardiovascular mixed results

Several observational studies have shown benefits of vitamin D supplements with cardiovascular disease. For example, the Framingham Offspring Study showed that those patients with deficient levels were at increased risk of cardiovascular disease (1).

However, a small randomized controlled trial (RCT), the gold standard of studies, called the cardioprotective effects of vitamin D into question (2). This study of postmenopausal women, using biomarkers such as endothelial function, inflammation or vascular stiffness, showed no difference between vitamin D treatment and placebo. The authors concluded there is no reason to give vitamin D for prevention of cardiovascular disease.

The vitamin D dose given to the treatment group was 2,500 IUs. Thus, one couldn’t argue that this dose was too low. Some of the weaknesses of the study were a very short duration of four months, its size — 114 participants — and the fact that cardiovascular events or deaths were not used as study end points.

Most trials relating to vitamin D are observational, which provides associations, but not links. However, the VITAL study was a large, five-year RCT looking at the effects of vitamin D and omega-3s on cardiovascular disease and cancer (3). Study results were disappointing, finding that daily vitamin D3 supplementation at 2000 IUs did not reduce the incidence of cancers (prostate, breast or colorectal) or of major cardiovascular events.

Mortality decreased

In a meta-analysis of a group of eight studies, vitamin D with calcium reduced the mortality rate in the elderly, whereas vitamin D alone did not (5). The difference between the groups was statistically important, but clinically small: nine percent reduction with vitamin D plus calcium and seven percent with vitamin D alone.

One of the weaknesses of this analysis was that vitamin D in two of the studies was given in large amounts of 300,000 to 500,000 IUs once a year, rather than taken daily. This has different effects.

Weight benefit

There is good news, but not great news, on the weight front. It appears that vitamin D plays a role in reducing the amount of weight gain in women 65 years and older whose blood levels are more than 30 ng/ml, compared to those below this level, in the Study of Osteoporotic Fractures (4).

This association held true at baseline and after 4.5 years of observation. If the women dropped below 30 ng/ml in this time period, they were more likely to gain more weight, and they gained less if they kept levels above the target. There were 4,659 participants in the study. Unfortunately, vitamin D did not show statistical significance with weight loss.

USPSTF recommendations

The U.S. Preventive Services Task Force recommends against giving “healthy” postmenopausal women vitamin D, calcium or the combination of vitamin D 400 IUs plus calcium 1,000 mg to prevent fractures, and it found inadequate evidence of fracture prevention at higher levels (6). The supplement combination does not seem to reduce fractures, but does increase the risk of kidney stones. There is also not enough data to recommend for or against vitamin D with or without calcium for cancer prevention. But as I mentioned previously, the VITAL study did not show any benefit for cancer prevention.

When to supplement?

It is important to supplement to optimal levels, especially since most of us living in the Northeast have insufficient to deficient levels. While vitamin D may not be a cure-all, it may play an integral role with many disorders. But it is also important not to raise the levels too high. The range that I tell my patients is between 32 and 50 ng/ml, depending on their health circumstances.

References:

(1) Circulation. 2008 Jan 29;117(4):503-511. (2) PLoS One. 2012;7(5):e36617. (3) NEJM. 2018 published online Nov. 10, 2018. (4) J Women’s Health (Larchmt). 2012 Jun 25. (5) J Clin Endocrinol Metabol. online May 17, 2012. (6) JAMA. 2018;319(15):1592-1599.

Dr. David Dunaief is a speaker, author and local lifestyle medicine physician focusing on the integration of medicine, nutrition, fitness and stress management. For further information, visit www.medicalcompassmd.com.

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By Matthew Kearns, DVM

I’ve always had trouble instituting New Year’s resolutions. Shortened daylight hours and colder weather make it sooooohhh difficult to get up early and exercise. I also instinctively look for starchy foods instead of fresh fruits and vegetables. Our pets face the same problems. 

Wild animals in colder climates slow down their metabolism and hibernate during winter months as temperatures drop and food becomes scarce. Domesticated dogs and cats are not so far removed from their wild ancestors that their own bodies react the same way. How do we avoid the inertia that inevitably sets in with winter weather?

The first thing is to keep an exercise routine in place. One of the few advantages of global warming is although temperatures drop, we don’t see as much snow and ice as in previous years. Sticking with daily walks helps keep their (and our) waistline at a manageable diameter. When the weather is not cooperating and our pets only go out long enough to do their business consider an indoor exercise routine. Rolling a ball to play fetch or using toys designed for cats to induce their stalking instincts are viable alternatives to playing outside. 

The second phase of our New Year’s resolutions is to take a closer look at calorie intake during colder months. I always recommend evaluating how many treats, rawhides, table scraps, etc. our pets receive. During the winter months we may need to decrease or eliminate these extras. 

I also see a lot of pets that gain weight the winter after they’ve been spayed or neutered and that can be difficult to take off again. Studies have shown that spaying and neutering dogs and cats does slow metabolism but, just because your pet was spayed or neutered does not mean that they will automatically become obese if we monitor their calorie intake and adjust properly. 

If we are exercising and reducing calories but not seeing a reduction in weight, it’s time to talk to our veterinarian about underlying disease. Glandular disorders such as underactive thyroid in dogs can lead to obesity and, without thyroid supplementation, no amount of diet and exercise will help them. Older dogs and cats frequently suffer from obesity secondary to arthritis. These pets exercise less because they are unable to move like when they were younger. 

Supplements and medications are available to help make them more comfortable and exercise more. Increased exercise and subsequent weight loss could reduce or eliminate medications (I recommend supplements lifelong).  

I hope this information is helpful in keeping our pets from gaining too much during the winter months. Now, onto my New Year’s resolution … UGH!!!

Dr. Kearns practices veterinary medicine from his Port Jefferson office and is pictured with his son Matthew and his dog Jasmine. Have a question for the vet? Email it to [email protected] and see his answer in an upcoming column.

A 2013 study found that when taken together, iron and calcium supplements increase the risk of developing glaucoma. Stock photo
Some supplements may increase risk
Dr. David Dunaief

By David Dunaief, M.D.

Glaucoma is the second-leading cause of blindness in the world, behind cataracts. It is neurodegenerative (deterioration of the optic nerve) with increased intraocular pressure (IOP) — pressure inside the eye — as an indicator that nerve damage is more likely. The most common types of glaucoma are open angle and angle closure. Open-angle glaucoma represents about 90 percent of U.S. cases and is caused by clogging of the eye’s drainage canals over time (1). Because it develops slowly and over time, its symptoms are not always obvious.

Glaucoma initially causes peripheral vision loss and then works its way inward to the central vision. If untreated, it can lead to irreversible blindness (2). The occurrence of this disease is rising, with an estimated three million Americans affected and a predicted level of roughly 3.4 million in the U.S. by 2020.

Fortunately, there are treatments. Some revolve around reducing fluid production in the eye, such as beta blockers and carbonic anhydrase inhibitors. Others work to increase fluid drainage, such as cholinergics and prostaglandin analogs. Still others do both (1). None of these treatments reverse lost vision or damage. They only slow or halt its progression to preserve your remaining sight. Therefore, prevention and early detection are crucial.

Glaucoma risk factors include age — starting at 40, although those over 65 have higher risk and those over 80 have the highest risk —and race, with African-Americans at a five-times higher risk than those of European ancestry. In the Baltimore Eye Survey, a family history of the disease dramatically increased risk, with siblings having greater probability than offspring of developing the disease (3). Other risk factors include steroid use, including asthma inhalers, eye injury, nearsightedness and hypertension. Finally, the higher the IOP, the greater the risk for progression in open-angle glaucoma (4).

Effect of increased visual field testing

In the Advanced Glaucoma Intervention Study, it was found that visual field testing by an ophthalmologist every six months for patients at higher risk was better at predicting disease progression than annual testing (5). The result was that, with more frequent testing, the researchers were 50 percent more likely to detect progression of the disease, if it were to occur.

Interestingly, the U.S. Preventive Services Task Force currently does not recommend screening for open-angle glaucoma, since it feels there is insufficient evidence (6). The American Academy of Ophthalmology recommends screening every two to four years starting at age 40, with increased frequency of every one to three years starting at age 55 and every one to two years for those 65 and older. More frequent screening is recommended for those who have more risk factors (7).

Preventative steps

There are several steps that may be valuable, including reducing chronic diseases associated with glaucoma such as type 2 diabetes, Alzheimer’s and erectile dysfunction. If we reduce their incidence, there may also be a reciprocal decline in glaucoma. In addition, avoiding or reducing supplementation with iron and calcium, while potentially increasing magnesium, may decrease incidence of the disease.

Diabetes and high blood pressure

In an analysis of two studies, diabetes increased the risk of open-angle glaucoma by greater than 200 percent (8). In the same analysis, however, systemic hypertension (high blood pressure) increased the risk by a meager 7 percent. This is yet another reason we need to control or prevent diabetes to preserve eye health, aside from diabetic retinopathy (disease of the back of the eye).

Erectile dysfunction association

Those with erectile dysfunction (ED) had an almost threefold increased risk of also having open-angle glaucoma, compared to those without the disorder (9). There may be vascular symptoms associated with open-angle glaucoma as demonstrated by the increased association with ED. The study suggests that the mechanism of action that both disorders have in common is endothelial dysfunction (inner lining of the blood vessels), which involves a decreased level of nitric oxide, a potent vasodilator, which enables the vessels to expand and relax. ED was also associated with high cholesterol and blood pressure, heart disease and diabetes. It is not unusual to find that many diseases have a common underlying pathology.

Supplements

A 2013 study found that supplementation with calcium and iron, looked at separately, increases risk of normal-tension glaucoma (NTG), glaucoma without increased pressure (10). The calcium and iron came from a variety of sources, including antacids, multivitamins and prescription and nonprescription supplements. Roughly one-third of glaucoma patients have NTG (11). Among Japanese patients, a study found that this number increases to two-thirds (12).

The supplementation study results showed that participants who took a composite of 800 mg daily of calcium were at an almost 2.5-times increased risk. Those who took 18 mg of iron on a daily basis were at an even higher risk, 3.8 times, of developing the disease. When taken together, iron and calcium increased risk by a resounding 7.2-fold. Interestingly, dietary sources of iron and calcium were associated with lower odds of glaucoma.

The good news is that a dose of 300 mg of magnesium citrate in patients with NTG showed a benefit in visual field over one month, compared to those who did not take magnesium (13). Although this was a randomized-controlled trial, it was also very small with only 30 patients.

While there are risk factors — such as family history, age and ethnicity — that can’t be changed, there are a number of modifiable factors as well. Glaucoma may be brought on by factors that are related to those causing systemic diseases. Therefore, it’s important to maintain good health overall to reduce the risk for glaucoma and its effects.

References:

(1) glaucoma.org. (2) Lancet. 2004;363(9422):1711. (3) Arch Ophthalmol. 1994;112(1):69. (4) Ophthalmology. 2007;114(10):1810. (5) Arch Ophthalmol. 2011;129(12):1521-1527. (6) Ann Fam Med. 2005;3(2):171. (7) AAO.org. (8) Br J Ophthalmol. 2012;96(6):872-876. (9) Ophthalmology 2012;119:289-293. (10) Curr Eye Res. 2013 Oct;38(10):1049-1056. (11) Ophthalmology. 1992;99(10):1499–1504. (12) Jpn J Ophthalmol. 1991;35(2):133–155. (13) Eur J Ophthalmol. 2010;20(1):131-135.

Dr. Dunaief is a speaker, author and local lifestyle medicine physician focusing on the integration of medicine, nutrition, fitness and stress management. For further information, visit www.medicalcompassmd.com or consult your personal physician.