Oral Nutritional Supplements Linked to Better Vitamin Levels

Teresa Carvalho, MS avatar

by Teresa Carvalho, MS |

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The use of oral nutritional supplements is associated with a higher intake of nutrients and better levels of certain vitamins in cystic fibrosis (CF) patients with poor respiratory and nutritional status.

These results are found in the study “Oral nutritional supplements in adults with cystic fibrosis: effects on intake, levels of fat-soluble vitamins, and bone remodeling biomarkers,” published in the journal Nutrients.

Due to a deficiency in enzymes necessary to help digest food, people with CF often experience pancreatic insufficiency, one of the common digestive symptoms in CF.

This deficiency — driven by the accumulation of thick mucus that clogs the pancreatic ducts — can cause patients not to absorb enough nutrients and calories from their food, ultimately resulting in low weight and height, as well as malnutrition.

In particular, CF patients have problems absorbing fats, making them prone to insufficiency in the fat-soluble vitamins A, D, E, and K.

As such, CF patients often are advised to take fat-soluble vitamin supplements because a good nutritional status — with an adequate amount of vitamins — can improve lung function and survival.

To better assess the impact of oral nutritional supplements (ONS) on CF patients’ nutritional, respiratory and muscle health, a team of researchers from Malaga, Spain, studied 59 adults with clinically stable CF, mean age 29.3 (range 16 to 67), who were seen during their annual appointment.

Body composition parameters such as body mass index (BMI), fat-free mass index (FFMI, an assessment of muscle mass, fat mass, and bone mineral density (BMD) were assessed.

The team also studied muscle strength and malnutrition, as defined according to the European Society for Clinical nutrition and Metabolism: Less than 15 kg/square meter (kg/m2) in women, and less than 17 kg/m2 in men.

Regarding nutritional status, participants were given a questionnaire about their intake of calories, fat-soluble vitamins, carbohydrates, proteins, lipids (fat), and omega-3 fatty acids — a type of fat the body cannot make on its own.

Blood levels of fat-soluble vitamins and bone remodeling biomarkers also were studied. Bone remodeling is the natural process of breakdown and formation of bone.

To gauge respiratory status, the team assessed exacerbations experienced in the year before the appointment, as well as lung function, as determined by spirometry tests — forced vital capacity (FVC), maximum expiratory volume in the first second (FEV1), and the FEV1/FVC ratio. FVC is is the amount of air a person can exhale after a deep breath, and FEV1 represents that volume in one second.

The amount of sputum produced per day was calculated by measuring it three days before the appointment.

Results showed that 13 patients (22%) were taking ONS. The most used, by three participants each, were Diben nutritional drink and Fresubin energy drink.

The researchers observed that patients taking ONS showed worse respiratory status when compared to those not taking them, as they revealed more respiratory exacerbations (3.6 vs. 2.0). They also produced a higher amount of sputum (25.8 mL vs. 19.7 mL) and their FEV1 levels tended to be lower (51.6% vs. 66.9%), although these differences were not statistically significant.

As for nutritional status, BMI was significantly lower in patients taking ONS (20.1 kg/m2 vs. 22.5 kg/m2) and FFMI also tended to be lower in this group (15.6 kg/m2 vs. 16.5 kg/m2).

In the group taking ONS, the scientists also observed higher levels of malnutrition (75.3% vs. 50%), lower BMD, and higher blood levels of a particular bone remodeling biomarker, known as RANKL (0.42 picomoles/L vs. 0.18 picomoles/L).

According to the team, malnourished patients have a higher risk of osteopenia (bone weakness) and osteoporosis — the loss of bone density, which increases the risk of fractures. As such, bone remodeling biomarkers are expected to be increased in those patients.

“When RANKL is overexpressed, it favors the development of osteopenia and osteoporosis in CF patients,” the team wrote.

The use of ONS may improve nutritional status and reduce the loss of bone mass in malnourished CF patients by providing fat-soluble vitamins, researchers said.

In fact, none of the participants taking ONS had deficiency of vitamins D and E. Particularly, blood levels of vitamin E were significantly higher in this group (1,488.3 mg/g vs. 1,174.3 mg/g).

Those taking ONS also showed a higher mean intake of calories (2,982.4 vs. 2,456), carbohydrates (6.2 vs. 4.7), proteins (2.4 vs. 1.6) and lipids (2.4 vs. 1.8). The values of carbohydrates, proteins and lipids are presented as kilogram of body weight.

According to the team, these results suggest that ONS “could not only be substituting patients’ dietary intake, but also supplementing their normal diet,” they wrote.

The researchers believe this study may serve as basis for future clinical trials evaluating the role of ONS in CF patients. As for study limitations, they mentioned the small number of patients and the fact that it was conducted at a single center.