Vitamin B12
Use of these medications is associated with a reduction in vitamin B12 levels, in part because delayed gastric emptying may affect B12 absorption. Low dietary intake of B12 while on the medications can also be to blame, though. The best food sources are animal proteins, so if possible, patients should prioritize having fish, lean meat, eggs, and dairy daily.
Vegetarians and vegans, who are at an increased risk for deficiency, can incorporate nutritional yeast, an excellent source of vitamin B12, into their daily routine. It is beneficial for patients to get blood work periodically to check on B12 status, because insufficient B12 can contribute to the fatigue patients experience while on the medication.
Calcium
Individuals should have calcium on their radar, because weight loss is associated with a decrease in bone mineral density. Adequate intake of the mineral is crucial for optimal bone health, particularly among postmenopausal women and those who are at risk of developing osteoporosis. The RDA for calcium is 1000-1200 mg/d, which an estimated 50% of obese individuals do not take in.
Although dairy products are well-known for being rich in calcium, there are other great sources. Dark green leafy vegetables, such as cooked collard greens and spinach, provide nearly 300 mg per cup. Tofu and sardines are also calcium powerhouses. Despite the plethora of calcium-rich foods, however, some patients may need a calcium supplement.
Vitamin D
Vitamin D deficiency or insufficiency is common among individuals with obesity, so even before these patients start the medications, supplementation may be warranted. The vitamin’s role in promoting calcium absorption, as well as in bone remodeling, make adequate intake essential for patients experiencing significant weight loss.
Clinicians should emphasize regular consumption of fatty fish, such as salmon, as well as eggs, mushrooms, and vitamin D–fortified milks. But unfortunately, that’s where the list of vitamin D–rich foods ends, so taking a vitamin D supplement will be necessary for many patients.
Regularly monitoring patients on GLP-1 RAs through blood work to check vitamin levels and body composition analysis can be helpful in assessing nutritional status while losing weight. Clinicians can also encourage their patients to work with a registered dietitian who is familiar with these medications, so they can develop optimal eating habits throughout their health journey.
Ms. Hanks, a registered dietitian in New York City, has disclosed no relevant financial relationships.
A version of this article appeared on Medscape.com.