The Vitamin D Riddle

THE VITAMIN D RIDDLE

I take a vitamin D supplement every day—800 international units (IU). Why? Because it’s what I’ve been hearing for years that a senior should be taking. Until now, I didn’t much question this beyond doing some research for my post Dietary Supplements—Do They Work? last February.

Vitamin D is necessary for building strong bones. Your body can only absorb calcium, the main component of bone, when this vitamin is present. Your body forms vitamin D naturally after exposure to direct sunlight; When ultraviolet (UV) rays hit your skin it triggers production of a chemical in your skin into an active form of the vitamin (calsiferol). You can also get the vitamin from certain foods including fortified milk and cereal and fatty fish such as salmon, tuna and mackerel. And you can get it from supplements.

Now, enter the riddle. How should you get your vitamin D and how much do you need? I found that there are two completely different camps on this question. A recent report from the Mayo Clinic suggests that most Americans get enough vitamin D without taking supplements. The other camp, the non-profit Vitamin D Council, recommends that adults intake 5,000 IU per day—through sunlight if you can but through supplements if you can’t.

Mayo Clinic

First, I’ll give excerpts from an adaptation of a Mayo Clinic Health Letter by Dr. Sundeep Khosla, Endocrinology in the March 13, 2018 article by Liza Torborg titled Mayo Clinic Q and A: Getting enough vitamin D

“In general, adults should consume 600 international units of vitamin D a day. That goes up to 800 international units a day for those over 70. National survey data indicate that most Americans don’t get enough vitamin D through their diets. However, the data also indicate that average blood levels of the vitamin are above what’s considered necessary for good bone health for most people. This implies that most American adults get enough vitamin D — most likely through sun exposure. (Boldface mine)

Severe and prolonged vitamin D deficiency is known to cause bone mineralization disorders such as rickets in children and osteomalacia in adults. Vitamin D deficiency also may contribute to osteoporosis

Although numerous studies have reported results associating vitamin D deficiency with various other diseases and conditions — such as fatigue, depression, chronic pain, heart disease, autoimmune disorders, infections, metabolic issues and cancer — clinical trials of vitamin D supplements in people with these conditions generally have failed to show benefit. This implies that a lack of vitamin D probably isn’t causing these conditions. Some experts argue that rather than being a cause of these kinds of illnesses, vitamin D deficiency may be a biological marker for them, signaling the presence of inflammatory processes related to the disease or condition.

Adults who may not get enough vitamin D generally fail to do so due to one or more of these reasons:

• Chronic condition
  Conditions that affect your absorption or processing of vitamin D can affect circulating levels of the vitamin. For example, having conditions such as inflammatory bowel disease or celiac disease, or having had bariatric surgery can affect your intestine’s ability to absorb vitamin D..
• Reduced skin synthesis
  People with darker skin are at greater risk of deficiency because greater amounts of melanin in the skin reduce the skin’s ability to produce vitamin D from sunlight. Aging also decreases the efficiency of vitamin D synthesis. Sunscreen, clothing and other UV protective measures that block skin’s exposure to the sun not only help prevent skin cancer, but also reduce production of vitamin D. (Underline mine)
• Limited sun exposure
  People who spend most of their time indoors generally have low levels of the vitamin. The amount of sun exposure needed for adequate vitamin D production is uncertain, but most estimates are no more than 15 minutes a day between 10 a.m. and 3 p.m., three times a week. However, this sun exposure must be balanced against your risk of skin cancer.

Most healthy American adults have adequate levels of vitamin D. Even 600 IU a day will correct a deficiency fairly quickly. However, taking too much vitamin D can overly increase your absorption of calcium, leading to problems such as kidney stones and damage to your heart and blood vessels. The Food and Nutrition Board recommends an upper limit of 4,000 international units a day to be safe.”

Vitamin D Council

Now, the other camp. Here are excerpts from the Vitamin D Council section of their website titled How do I get the vitamin D my body needs?

In the 21^st century, it’s hard to get daily full body sun exposure. On the days that you can’t get enough sun exposure, taking a supplement is an effective way to get the vitamin D your body needs. It‘s also a good way to get vitamin D if you’re worried about exposing your skin to the sun.

The Vitamin D Council recommends daily intakes of 5,000 IU/day with an upper limit of 10,000 IU/day. The Food and Nutrition Board (U.S. Government) recommends 600 IU/day, 800 IU/day seniors with an upper limit of 4,000 IU/day. Why are the recommendations so different? Some researchers believe that there isn’t enough evidence to support taking higher amounts of vitamin D yet. On the other hand, some researchers believe that research is proving, or will prove, that taking lower amounts isn’t enough.

Can I get sun exposure and take supplements?

Yes. In fact, that is the Vitamin D Council’s recommendation. On days that you do not get enough full body sun exposure, it is important to take a supplement. For most people on the Monday-Friday indoor work schedule, that means taking a supplement 5-6 days a week and getting sun exposure on a day or two during the weekend.

Can I get vitamin D from my diet?

There are small amounts of vitamin D in a few foods, which makes it nearly impossible to get what you need from food.

Under the Health Conditions section of the website, Dr. John Cannell, Founder and Medical Director of the Vitamin D Council, writes about dozens of afflictions that are possibly benefited by taking abundant amounts of supplemental vitamin D.  These include such varied conditions as acne, dental carries, influenza, Parkinson’s disease, pneumonia and tuberculosis.

Well, that’s quite a contrast between the Mayo Clinic and the Vitamin D Council. Personally, I’m somewhat changing my ways. Most days here in temperate Ventura, I’m outdoors for a spell running, biking or swimming. Even though I put on sun block, it wears off after a period of time especially when I sweat. On these days I think I’m meeting the vitamin needs from the sun. On the days I don’t exercise outside (like swimming in the YMCA indoor pool instead of the ocean) or on those rare overcast days or when I’m off on vacation, I’ll continue to take my 800 IU daily supplement.

If you fall into a risk category, talk to your health care provider about whether you need a supplement. Otherwise, you can decide for yourself how much vitamin D you need and how to get it—through sunlight or through supplements or both.