When women have weight loss surgery, their bodies struggle to absorb vitamin D and calcium, especially if they’re under 45 years old. Researchers studied 305 women who had this surgery and found that younger women’s vitamin D levels dropped more over time, even though they were taking supplements. This happens because younger women’s bodies may need more of these nutrients, or they might not be taking their supplements consistently. The study suggests that doctors should give younger women stronger support and possibly different supplement plans to keep their bones healthy after surgery.

The Quick Take

  • What they studied: Whether women under and over 45 years old have different vitamin D and calcium levels after weight loss surgery
  • Who participated: 305 women having weight loss surgery at a hospital in England, split into two groups: 123 women under 45 and 182 women over 45
  • Key finding: Younger women (under 45) had significantly lower vitamin D and calcium levels 12 and 24 months after surgery, even though both groups took the same supplements
  • What it means for you: If you’re a younger woman considering weight loss surgery, you may need extra attention to vitamin D and calcium intake after the procedure. Talk to your doctor about a personalized supplement plan, as the standard approach may not be enough for your body’s needs.

The Research Details

This was an observational cohort study, which means researchers followed a group of women over time and measured their vitamin levels at different points. The 305 women were divided into two age groups: those under 45 and those over 45. All women had weight loss surgery and were given standard calcium and vitamin D supplements to take daily. Researchers measured their blood vitamin D, calcium, and other related nutrients before surgery and then at regular intervals for 24 months (2 years) after surgery.

The researchers looked at how vitamin levels changed over time and compared the two age groups to see if age made a difference. This type of study is good for understanding what happens in real-world situations, though it can’t prove that age directly causes the differences—it just shows that the differences exist.

Understanding how age affects vitamin absorption after weight loss surgery is important because vitamin D and calcium are critical for bone health, immune function, and overall wellness. If younger women aren’t getting enough of these nutrients, they could develop weak bones or other health problems years later. This research helps doctors know which patients need extra support and monitoring.

This study has several strengths: it included a reasonably large number of women (305), followed them for a full 2 years, and measured multiple related nutrients to get a complete picture. The study was conducted at a university hospital, which typically has good quality controls. However, the study couldn’t prove cause-and-effect—it only showed that younger women had lower levels. The researchers couldn’t fully explain why this happened, whether it’s due to body chemistry, supplement adherence, or other factors. The study was also done in one region of England, so results might differ in other populations.

What the Results Show

Both age groups showed improvement in vitamin D levels within the first 4 months after surgery, which is good news—the supplements were working initially. However, after that initial improvement, the younger women’s vitamin D levels dropped more significantly than the older women’s levels. By 12 months and continuing at 24 months, younger women had noticeably lower vitamin D levels despite taking the same daily supplements.

Calcium levels told a similar story. Both groups started with adequate calcium, but levels gradually declined over the 2-year period. Again, younger women showed a steeper decline and had significantly lower calcium at the 12 and 24-month marks.

Parathyroid hormone (PTH) is a chemical your body makes to help control calcium levels. Interestingly, younger women started with lower PTH levels, but their PTH increased over time. By 12 months, both age groups had similar PTH levels, suggesting their bodies were working harder to maintain calcium balance.

The pattern of results suggests that younger women’s bodies may have higher demands for vitamin D and calcium, possibly related to reproductive hormones and bone remodeling that occurs during reproductive years. The fact that PTH levels increased in younger women indicates their bodies were responding to low calcium by trying to pull more calcium from their bones—a concerning sign if it continues long-term. The study also hints that younger women may not be taking their supplements as consistently as older women, though this wasn’t directly measured.

Previous research has shown that vitamin D deficiency is common in people with obesity and can worsen after weight loss surgery. This study adds important new information by showing that age significantly affects how well the body maintains these nutrients after surgery. Most previous studies didn’t specifically compare younger and older women, so this fills an important gap. The findings align with what we know about reproductive hormones affecting nutrient absorption and bone metabolism.

The study couldn’t determine exactly why younger women had lower levels—it could be due to differences in how their bodies absorb nutrients, differences in how consistently they took supplements, or other unmeasured factors. The study only included women in one hospital in England, so results might be different in other countries or populations. The researchers didn’t measure supplement adherence directly, so they couldn’t confirm whether younger women were actually taking their pills as prescribed. Additionally, the study didn’t look at long-term bone health outcomes, so we don’t know if these lower vitamin levels actually cause bone problems.

The Bottom Line

Women under 45 who have weight loss surgery should: (1) Work with their doctor to create a personalized supplement plan rather than relying on standard dosing; (2) Get their vitamin D and calcium levels checked regularly (every 6-12 months) after surgery; (3) Take supplements consistently every day and consider using reminders or pill organizers; (4) Discuss any barriers to taking supplements with their healthcare team. These recommendations are supported by this study’s findings, though more research is needed to determine the optimal supplement doses for younger women.

This research is most relevant for women under 45 who are considering or have had weight loss surgery. It’s also important for doctors and nutritionists who work with bariatric surgery patients. Women over 45 should still take their supplements and get monitored, but the standard approach appears to work better for them. Men who have weight loss surgery may have different nutritional needs and shouldn’t assume these findings apply to them.

Vitamin D levels improved within 4 months after surgery, but the decline in younger women happened gradually over 12-24 months. This means you might feel fine initially, but problems could develop over time if vitamin levels aren’t properly managed. It’s important to stay consistent with supplements and monitoring for at least 2 years after surgery, and potentially longer.

Want to Apply This Research?

  • Track daily vitamin D and calcium supplement intake with a simple yes/no checklist. Set a daily reminder at the same time each day (e.g., with breakfast) to take supplements and log completion in the app.
  • Use the app to set a daily alarm for supplement time and create a habit streak to maintain consistency. Users can also log any symptoms (fatigue, bone pain, muscle weakness) that might indicate deficiency, which they can discuss with their doctor.
  • Schedule lab test reminders every 6 months to check vitamin D and calcium levels. Create a chart in the app to track results over time and share with healthcare providers. Set goals for supplement adherence (aim for 90%+ compliance) and review monthly to identify patterns or barriers.

This research provides important information about vitamin D and calcium levels after weight loss surgery, but it should not replace personalized medical advice. If you are considering weight loss surgery or have had this procedure, consult with your doctor or a registered dietitian about your individual nutritional needs and supplement plan. This study was observational and cannot prove that age directly causes vitamin deficiencies—only that differences exist between age groups. Always follow your healthcare provider’s recommendations for supplementation and monitoring, as individual needs vary based on many factors not covered in this study.