Researchers studied 220 young women in India and found that most of them don’t get enough vitamin D or calcium, which are crucial nutrients for building and maintaining strong bones. The study discovered that 85% of the women had low vitamin D levels, and those with vitamin D deficiency weren’t getting enough sun exposure or eating enough calcium-rich foods like milk and dairy products. The researchers found clear connections between vitamin D levels, calcium intake, and bone health markers in the blood. This research highlights why it’s important for women to spend more time in the sun and eat more calcium-rich foods to keep their bones healthy.

The Quick Take

  • What they studied: Whether vitamin D deficiency and low calcium intake are connected to weaker bones in young women living in Indian cities
  • Who participated: 220 young urban women in India, with an average age in their reproductive years; 108 of these women had vitamin D deficiency
  • Key finding: About 85% of the women studied had vitamin D levels that were too low, and those with deficiency were eating only about 480 mg of calcium per day—far less than the recommended 1000 mg. Three-quarters of the vitamin D deficient women spent less than 15 minutes per day in the sun.
  • What it means for you: If you’re a young woman living in a city, you may need to intentionally get more sun exposure and eat more calcium-rich foods like milk, yogurt, and cheese to protect your bone health. This is especially important if you spend most of your time indoors. However, this study shows associations, not proof of cause-and-effect, so talk to your doctor about your individual needs.

The Research Details

This was a cross-sectional study, which means researchers took a snapshot in time by measuring vitamin D levels, calcium intake, sun exposure, and bone health markers in 220 women all at once. They didn’t follow the women over time or randomly assign them to different groups. Instead, they looked at all the women together and analyzed the patterns they found.

The researchers measured several things: vitamin D levels in the blood, a hormone called parathyroid hormone (PTH) that controls calcium, and bone health markers like osteocalcin and bone-specific alkaline phosphatase. They also asked women about their diet, sun exposure, and lifestyle. They then looked for connections between these measurements.

This type of study is useful for identifying patterns and connections in a population, but it can’t prove that one thing causes another. It’s like noticing that people who carry umbrellas are wet—you can see the connection, but you can’t tell if the umbrella caused the wetness or if the rain caused both.

This research approach is important because it gives us a real-world picture of what’s actually happening in a specific population of women. By studying women in their normal environment rather than in a controlled lab setting, the researchers could see the actual patterns of vitamin D deficiency, calcium intake, and sun exposure that exist in urban India. This helps doctors and public health officials understand what problems are most common and urgent.

This study has several strengths: it measured actual blood levels of vitamin D rather than just asking people to remember, and it looked at multiple bone health markers rather than just one. However, because it’s a cross-sectional study, it can only show that things are connected, not that one causes the other. The study was published in Scientific Reports, a well-respected journal. One limitation is that we don’t know if these findings apply to women in other parts of India or other countries with different climates and diets.

What the Results Show

The study found that vitamin D deficiency is extremely common in these young Indian women: 64.5% had deficient levels and 20.2% had insufficient levels, meaning 85% total had suboptimal vitamin D. Among the women with vitamin D deficiency, 75% reported spending less than 15 minutes per day in the sun, which is surprising given that India has abundant sunlight. This suggests that urban lifestyle—spending time indoors at work, school, or home—is a major factor.

The calcium intake was shockingly low: women were eating only about 480 mg of calcium per day on average, which is less than half the recommended amount of 1000 mg per day for adult women. This low calcium intake was strongly connected to the vitamin D deficiency problem.

When researchers looked at blood markers of bone health, they found that vitamin D levels were negatively correlated with PTH (a hormone that increases when vitamin D is low) and with osteocalcin (a protein made by bone-building cells). This means that as vitamin D went down, these other markers went up, suggesting the body was struggling to maintain bone health. Interestingly, osteocalcin was positively connected to calcium intake and milk consumption, suggesting that eating more dairy products was associated with better bone health markers.

The study found that the ratio of calcium to phosphorus in the diet was also important for bone health. Women who had a better balance between these two minerals showed better osteocalcin levels. Milk intake specifically was connected to better bone health markers, suggesting that dairy products may be particularly beneficial. The researchers also noted that the combination of vitamin D deficiency, low calcium intake, and limited sun exposure created a ‘perfect storm’ for poor bone health in these young women.

Previous research has shown that vitamin D deficiency is common in many parts of the world, but this study confirms that it’s particularly prevalent in India despite abundant sunlight. The finding that urban lifestyle and indoor work are major contributors aligns with other research showing that modern city living reduces sun exposure. The connection between low calcium intake and poor bone health markers matches what scientists have found in other populations. However, this study adds important information about how these factors work together in young Indian women specifically.

This study has several important limitations to keep in mind. First, it only looked at women at one point in time, so we can’t tell if vitamin D deficiency causes poor bone health or if poor bone health causes vitamin D deficiency. Second, the study only included 220 women from urban areas in India, so the results may not apply to rural women or women in other countries. Third, the researchers relied on women to remember and report what they ate, which can be inaccurate. Fourth, some of the statistical associations were borderline (p-values close to 0.05), meaning they might not be as strong as they appear. Finally, the study didn’t measure actual bone fractures or bone strength directly—only blood markers and bone density, which are indirect measures of bone health.

The Bottom Line

Based on this research, young women in urban areas should aim to: (1) Spend at least 15-30 minutes in direct sunlight several times per week to boost vitamin D production naturally; (2) Eat calcium-rich foods daily, aiming for about 1000 mg per day through sources like milk, yogurt, cheese, leafy greens, and fortified foods; (3) Consider a calcium-to-phosphorus ratio that favors calcium by limiting processed foods high in phosphorus; (4) If you have symptoms of vitamin D deficiency or concerns about bone health, ask your doctor about blood tests and possible supplementation. The confidence level for these recommendations is moderate—the research shows clear associations, but we’d benefit from more studies that follow women over time.

Young women living in urban areas, especially those who spend most of their time indoors, should pay attention to this research. Women with limited sun exposure, those following vegetarian diets low in dairy, and those with a family history of osteoporosis should be particularly concerned. This is also relevant for women in other sunny countries where vitamin D deficiency is common despite good weather. However, if you live in a northern climate with limited sunlight or if you already take vitamin D supplements and eat adequate calcium, this research may be less directly applicable to you.

Building stronger bones is a slow process. It typically takes 3-6 months of consistent vitamin D and calcium intake to see improvements in blood markers of bone health. For actual improvements in bone density, you may need 1-2 years of consistent effort. However, the benefits of adequate vitamin D and calcium extend beyond bones—you may notice improvements in energy, mood, and muscle strength within weeks to months.

Want to Apply This Research?

  • Track daily calcium intake in milligrams, aiming for 1000 mg per day. Log specific foods like milk (300 mg per cup), yogurt (300 mg per serving), cheese (200 mg per ounce), and leafy greens. Also track minutes of direct sun exposure daily, aiming for at least 15 minutes most days of the week.
  • Set a daily reminder to spend 15 minutes outdoors in sunlight during mid-morning or late afternoon (when UV rays are less intense). Add a ‘calcium goal’ to your app that suggests calcium-rich foods at meals and snacks. Create a simple checklist: ‘Sun exposure today?’ and ‘Calcium intake logged?’ to build these habits.
  • Over 3 months, monitor trends in your sun exposure and calcium intake using the app’s analytics. Take a screenshot of your average daily calcium intake and sun exposure each month. If possible, work with your doctor to retest vitamin D levels every 3-6 months to see if your lifestyle changes are improving your blood levels. Use the app to note any changes in energy, bone health, or overall wellness.

This research shows associations between vitamin D deficiency, low calcium intake, and bone health markers in young Indian women, but it does not prove cause-and-effect relationships. This information is for educational purposes only and should not replace professional medical advice. If you have concerns about your bone health, vitamin D levels, or calcium intake, please consult with your doctor or a registered dietitian who can assess your individual needs and recommend appropriate testing or supplementation. This is especially important if you have a family history of osteoporosis, are pregnant or breastfeeding, or take medications that affect bone health.