Choice of Procedure in Patients with Pre-existing Deficiency

With regard to the choice of procedure in patients with pre-existing deficiency, procedures like biliopancreatic diversion with duodenal switch (BPD-DS) may be avoided as it is associated with significant malabsorption, wherein hypovitaminosis D and secondary hyperparathyroidism is difficult to manage in spite of adequate supplementation [33].

Amongst the rest of the commonly performed bariatric procedures, there is conflicting data on whether roux en Y gastric bypass (RYGB) causes more significant effects compared to sleeve gastrectomy (LSG). With no clear recommendations available and with the understanding that the changes are closely associated with the body composition, either procedure should be considered based on other clinical parameters and RYGB would not be a contra-indication.

Calcium Recommendation in Bariatric Surgery

Major food sources of calcium include dairy products, low-oxalate vegetables like cabbage, cauliflower, cucumber, mushrooms, peas, radish (to avoid high oxalate vegetables like beetroot, carrot, eggplant, ladies finger (okra), potato, sweet potato, legumes and sesame seeds) and fortified foods. For vitamin D primary sources are fortified dairy products, egg yolk and fatty fish [14]. Magnesium is found in nuts (especially almonds, cashews), seeds, whole grains, seafood, legumes tofu, yogurt, green leafy vegetables such as spinach, fruits like avocado, figs and banana.

Adequate dietary intake of calcium, magnesium and vitamin D rich food substances needs to be ensured. More importantly food interactions need to be noted. High fat in foods hinder calcium absorption and reduce the bioavailability of calcium. Oxalic acid in vegetables, phytic acid in cereal bran, and caffeine in coffee also decreases calcium absorption. Phosphorus in cola and processed foods, high protein and sodium impairs calcium absorption by increasing calcium excretion through the kidneys. Magnesium levels can be lowered by high intake of coffee, soda, alcohol, salt, during heavy menstrual periods, excessive sweating and prolonged stress. As high protein decreases the bone mass due to its acid nature more concern should be given to increase the intake of alkalining fruits and vegetables rather reducing protein sources [34]. Also high protein diets particularly with animal protein actually result in greater bone mass.

In addition to dietary sources, medical supplementation becomes important in order to replace ongoing losses especially in malabsorptive procedures. It has been demonstrated that calcium and vitamin D supplementation may attenuate the risk of bone loss following bariatric surgery [35, 36]. Expert recommendations for daily supplementation are 1200-1500 mg calcium and at least 3000 international units of vitamin D. Calcium citrate is safer than calcium carbonate that in large quantities can evoke a ‘milk-alkali’ syndrome [37]. Calcium citrate also reduces the risk of kidney stone formation [38]. This is of importance in RYGB procedures that appear to increase the risk of urinary stone disease [39]. Magnesium oxide and citrate are commonly used magnesium supplementations, but in case of intolerance, this can be replaced for IM or IV injections (magnesium sulphate, 100 mg/mL; 5 and 10 mL ampoules). Hence encouraging adequate intake with replacements with appropriate treatment of deficiencies is of prime importance.

35 Calcium and Vitamin D Deficiencies in Bariatric Surgery

The recommended dietary allowance for calcium, phosphorus, vitamin D, magnesium

Nutrients

Country

Males

Females

Calcium (mg/day)

RDA* (India) (39)

600

600

RDA* (US) (40)

1000

1000

RNI** (UK) (41)

700

700

NRV*** (Australia/New Zealand) (42)

1000

1000

Vitamin D (mcg/day)

RDA* (India) (39)

10

10

RDA* (US) (40)

15

15

RNI** (UK) (41)

5

5

NRV*** (Australia/New Zealand) (42)

5-10

5-10

Phosphorus (mg/day)

RDA* (India) (39)

600

600

RDA* (US) (40)

700

700

RNI** (UK/EU) (41)

550

550

NRV*** (Australia/New Zealand) (42)

1000

1000

Magnesium (mg/day)

RDA* (India) (39)

340

310

RDA* (US) (40)

420

320

RNI** (UK) (41)

300

270

NRV*** (Australia/New Zealand) (42)

400-420

310-320

RDA* recommended dietary allowances, RNI** reference nutrient intake, NRV*** nutrient reference value

293

 
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