Vitamin D for Joint Supplements: A Primer

Nutrition researchers and health experts continue to debate the sweet spot for an optimal intake of vitamin D, but they all agree on one troubling fact: Too many adults (and children) are failing to get enough of this essential vitamin to meet the body’s basic needs. Over time, adults who are deficient develop osteomalacia (adult rickets), a classic deficiency disease that usually rears its ugly head in the form of bone pain and muscle weakness.

If you’re a product developer working in the joint health space, consider adding vitamin D to your next formula. Why? By helping to prevent vitamin D deficiency and keep osteomalacia and its achy symptoms at bay, it allows all consumers to fully feel the comforting benefits of ingredients that target joint health.

Need inspiration? Here are seven vitamin D basics to get your creative juices flowing:

1. Vitamin D is an at-risk nutrient.

Vitamin D is now considered a nutrient of public health concern because too many people are failing to get enough from dietary sources or sun exposure. Among U.S. adults, the prevalence of vitamin D deficiency is about 40 percent for most age groups, according to a recent NHANES national nutrition survey. For people in their late 50s or early 60s—a key demographic for joint health supplements—the prevalence of vitamin D deficiency soars to almost 50 percent. (Nutr Res. 2011;31(1):48-54)

2. Vitamin D body stores are easy to measure.

The best indicator of vitamin D status is the serum level of 25-hydroxyvitamin D, also known as 25(OH)D. It’s the major circulating form of vitamin D in the body. According to the Institute of Medicine’s Food and Nutrition Board, a serum 25(OH)D level of at least 20 ng/mL is needed to support basic bone health in healthy people; anything less is inadequate. When it dips below 12 ng/mL, a full-blown deficiency exists, leading to osteomalacia.

3. Vitamin D exists in two forms.

Vitamin D3 (cholecalciferol) is the most common form of vitamin D. It readily raises serum 25(OH)D levels and is backed by research. Vitamin D3 is typically derived from lanolin, however, which makes it a no-go for vegans and vegetarians. For these consumers, consider a plant-derived D3 such as from lichen or plant-derived vitamin D2 (ergocalciferol).

3. Vitamin D supplementation predictably raises body stores.

For every 40 IU/day of vitamin D3 consumed, the incremental increase in serum 25(OH)D levels is reported to be about 0.5 ng/mL when body stores are low and about 0.3 ng/mL when body stores are higher. (It takes a few months to see the effect.) So, a formula providing 800 IU/day of D3 would be expected to increase serum 25(OH)D levels by about 6 to 10 ng/ml. By contrast, vitamin D2 is reported to be much less efficient with an incremental increase in serum 25(OH)D of about 0.12 ng/mL per 40 IU/day. (Osteoporos Int. 2005;16(7):713-716)

4. Vitamin D experts disagree on the optimal target.

Recommendations for an optimal serum 25(OH)D level vary widely among health institutions and practitioners and are in the range of 20 ng/mL to 80 ng/mL. Recommendations above 40 ng/mL tend to be based on observational studies that can show a correlation, but not a causal link, between vitamin D status and health status or on intervention studies involving the elderly or people with diseases. For now, more research is needed to confirm additional body benefits of a serum 25(OH)D level above 40 ng/mL for healthy people.

5. Vitamin D toxicity is real.

The Institute of Medicine has established the upper safety limit for vitamin D at 4,000 IU/day for healthy people. Since excessive vitamin D intake is associated with high blood calcium, which has its own set of clinical concerns, it would be prudent to formulate a supplement intended for daily use with this safety limit in mind. Also, don’t forget that a daily joint formula may be taken with a daily multivitamin that likely contains vitamin D.

7. Vitamin D has a new label look.

Under the FDA’s final rule, Revision of the Nutrition and Supplement Facts Labels, the Daily Value for vitamin D has doubled (from 400 IU to 800 IU) and the unit of measure has changed from International Units (IU) to micrograms (1 mcg = 40 IU). This revision may affect “high potency," “excellent source" or similar nutrient content claims anchored on the Daily Value. For now, the operative word is “may" as the FDA expects to address this issue in a separate rule in the near future. Stay tuned.

Kathleen Dunn, M.P.H., R.D., is a registered dietitian, author and industry consultant with over 25 years of experience in health and wellness. Her technical expertise is behind the successful launch of hundreds of premium branded and private label dietary supplements. Dunn is the co-author of Eating for A's, a month-by-month nutrition and lifestyle guide to help raise smarter kids.