Nutrient deficiency patterns and all-cause and cardiovascular mortality in older adults with hypertension: a latent class analysis – BMC Public Health

The study investigated and established the dietary nutrient deficiency patterns in older adults with hypertension, identified potential predictors of dietary nutrients deficiencies, and analyzed the impact of these patterns on all-cause and cardiovascular mortality, based on NHANES 2003–2014. We identified four distinct patterns of dietary nutrient deficiencies in older adults with hypertension using the LCA method: Class 1—Adequate Nutrient, Class 2—Nutrient Deprived, Class 3—Low Fiber, Magnesium and Vitamin E, and Class 4—Inadequate Nutrient. Each pattern exhibits unique demographic and anthropogenic characteristics and varying mortality risks. The all-cause and cardiovascular mortality were found to be the lowest in class1 (Adequate Nutrient) and the highest in class 2 (Nutrient Deprived). In class 3 (Low Fiber, Magnesium, and Vitamin E), which closely resembled the “Adequate Nutrient” class but with lower levels of vitamin E, fiber, and magnesium, both all-cause and cardiovascular mortality were significantly higher than class 1 (Adequate Nutrient). The risk of all-cause and cardiovascular mortality significantly increased when the deficient of fiber, Magnesium, and Vitamin E, and gradually increased as the nutrients deficiencies increased. The study suggested the dietary nutrients deficiency patterns of vitamins, dietary fiber and minerals had a great effect on all-cause and cardiovascular mortality risk among older adults with hypertension, especially fiber, magnesium, and vitamin E.

To the best of our knowledge, this study represents the first establishment of nutritional deficiency patterns in a nationally representative sample of older adults with hypertension. The four classes exhibited disparities in meeting the minimum daily recommended intakes of vitamins, fiber, and minerals. In terms of meeting the minimum daily recommended nutrient intakes, the “Adequate Nutrient” class performed best, followed by the “Low Fiber, Magnesium, and Vit E” class. The “Inadequate Nutrient” and “Nutrient Deprived” classes had a higher proportion of individuals not reaching the minimum daily recommended intakes for most nutrients. The most notable disparity between the “Adequate Nutrient” and “Low Fiber, Magnesium, and Vit E” classes lies in the intake of fiber, magnesium, and vitamin E. The classes of “Nutrient Deprived,” “Low Fiber, Magnesium, and Vit E,” and “Inadequate Nutrient” exhibited a standard-achieving rate for fiber, magnesium, and vitamin E below 10%, indicating that these three nutrients are most likely to be deficient in older adults with hypertension. A recently published study has identified the patterns of nutritional deficiency and evaluated their effects on depression across all age groups in NHANES 2017–2018. The nutrients, including dietary fiber, folate, vitamin B1, vitamin B12, vitamin K, calcium, magnesium, iron, zinc, copper and selenium were utilized for the establishment of classes [27]. Similar to our study, the percentages of dietary fiber and magnesium that met the minimum daily recommended intake were less than 20%, whereas vitamin E was not included in their investigation [27]. Our nutrient profile contained a greater range of essential vitamins, including vitamins A, C, D and E in comparison to their study. This more accurately reflects the true status of nutrients and their interactions.

Analysis of predictors about nutrient deficiency classes revealed that age was a significant risk factor for three nutrient deficiency classes (the class 2, 3 and 4). Nutrition and diet survey showed the proportion of inadequate intake of essential nutrients increased with age [28]. The US nationally representative biochemical data, based on NHANES 2003–2006, showed that 30–36% of older adults suffer from one or more micronutrient deficiencies [29]. Low energy requirements, functional losses and socioeconomic factors devoted to inadequate nutrition in older adults, and the inadequate nutritional status would be further aggravated with advancing age [28, 30, 31]. Our study suggested that higher than high school was a significant protective factor of three nutrient deficiency classes. Education, as an important component of socioeconomic status, exhibited a positive correlation with nutritional status [27] and clinical prognosis [32]. In the study, it was observed that female exhibited a protective effect against class 3. Previous studies have indicated that females exhibit a greater concern for maintaining a healthy diet and nutrient intake, and consume more plant-based foods [33]. However, female is a risk factor for nutrient deprived. Our study focuses on the older adults with hypertension, and their age is the oldest in nutrient deprived class. We speculate that intake decreases significantly with age in older women, which may result in female as a risk factor in nutrient deprived class. It has been shown that overweight and obesity has adverse impact on the nutritional status of individuals. Overweight and obesity are considered as a malnutrition state, usually with important deficiencies in vitamins, minerals and dietary fiber [34]. Our result showed that BMI was identified as a risk factor for nutrients deficiencies classes, which was in line with previous studies. The study found a significant variation in the impact of ethnicity on nutrient deficiency classification. Consistent with previous findings, significant disparities in dietary patterns and quality have been established based on ethnicity and race [35,36,37]. The disparities in dietary components and nutrient intake might be attributed to variations in geography, socioeconomic status, environment, behavioral and lifestyle factors, as well as policy guidance among different ethnicities [38]. A major characteristic for cardiovascular disease is the significant losses of essential nutrients including vitamins, minerals, and dietary fiber [39,40,41]. Nutrient intervention is a pivotal component in the prevention and management of cardiovascular disease, with its significance becoming increasingly indispensable [42]. In our study, cardiovascular disease significantly increased the likelihood of belonging to the three classes of nutrient deficiency patterns. Overall, age, ethnicity, BMI, and cardiovascular disease may serve as potential predictors of nutrient deficiency; however, this association is reversed for females and those with higher education.

More significantly, the present study is the first to directly provide evidence on the association of nutrient deficiencies with all-cause and cardiovascular mortality in older adults with hypertension. It was obvious that older adults with hypertension who met most nutritional values in “Adequate Nutrient” class exhibited the lowest all-cause and cardiovascular-cause mortality rates, while those who failed to meet most nutritional values in the “Nutrient Deprived” class displayed a completely opposite trend in terms of all-cause and cardiovascular mortality. Our findings are consistent with previous research, which has demonstrated a significant association between the intake of dietary fiber, vitamins, and minerals and mortality rates. Conversely, inadequate intake of these nutrients is associated with an increased risk of mortality [16, 18, 20, 21, 43]. In the study, Class 3 “Low Fiber, Magnesium, and Vitamin E” ranks second in terms of nutrient sufficiency, following Class 1 “Adequate Nutrient.” However, there exist significant disparities in all-cause and cardiovascular mortality between Class 1 and Class 3. It is noteworthy that participants in class 3 had greater opportunities to meet the minimal recommended intakes of nutrients, except for dietary fiber, magnesium, and vitamin E, compared to those in class 4. Adequate intake of these individual nutrients has been previously associated with reduced risks of all-cause and cause-specific mortality [18, 44]. However, the difference of the all-cause and cardiovascular mortality between class 3 and class 2, class 4 is minimal. More adequate intakes of these nutrients expect dietary fiber, magnesium, and vit E failed to significantly reduce the risk of all-cause and cardiovascular mortality in class 3, compared with class 2 and 4 in our study. However, the cardiovascular mortality is lower in class 4 than class 3, and a similar trend is also seen in cardiovascular mortality risk. Possibly it is due to the limited sample size, the cardiovascular deaths are much few, which caused deviation. The results suggested the intakes of fiber, magnesium, and vitamin E might play a critical role in all-cause and cardiovascular mortality risk among older adults with hypertension compared with other nutrients, when considering the holistic effects of diet nutrients on mortality.

Dietary fiber has been paid great attention to due to its distinct role in health recently. Dietary fiber has been confirmed to improve and delay many chronic diseases, and reduce the risk of mortality [19, 45]. The effects of dietary fiber on reducing mortality risk may be attributed to relieve the inflammation, improve overall metabolic health and develop healthy gut microflora [46]. Magnesium is involved in a variety of physiological functions, and is considered as a cofactor of hundreds of enzymes participated in in essential reactions in the body [47]. Humans get magnesium by consuming magnesium-rich foods to maintain magnesium homeostasis, but there is relatively common phenomenon of magnesium deficiency, 68% of US adult population have less than the recommended dietary allowance of magnesium [48]. Hypertension in old adults and magnesium deficit are two frequent coexisting conditions [49]. A meta-analysis based on 40 prospective cohort studies found the significantly protective effect of magnesium intake against stroke, heart failure, diabetes, and all-cause mortality, and a certain degree of dose-dependent, respectively [50]. Magnesium might reduce the mortality risk through exerting potential effects on antiplatelet, maintaining glucose and insulin homeostasis, improving lipid metabolism and endothelial function, enhancing vascular and myocardial contractility, keeping gene stability, and controlling inflammation [51]. Vitamin E is an important dietary antioxidant and anti-inflammatory vitamin, can inhibit LDL oxidation and prevent oxidative damage of the pathological process in many chronic diseases[16]. But the influence of vitamin E on the risk of many chronic diseases and mortality remains controversy, and there is no consistent conclusion. Forty-four studies were included in a meta-analysis of dietary vitamin E and risk of cardiovascular disease, stroke, cancer, and mortality, respectively [52]. The results of meta-analysis found dietary vitamin E was significantly associated with cardiovascular disease, stroke, cancer, and mortality in the nonlinear dose–response analysis [52]. In our study, the inadequate intake of dietary fiber, magnesium, and vitamin E significantly increased the all-cause and cardiovascular mortality risk in older adults with hypertension, the three nutrient combinations may play a positive role in its effect on risk of mortality. Dietary fiber, magnesium, and vitamin E should be considered as a marker of adherence to a healthy diet. Early nutritional intervention of increasing intake of dietary fiber, magnesium, and vitamin E might contribute to reduce the mortality risk in older adults with hypertension. But its exact mechanism remains to be studied further.

Our finding suggested the mortality risk of older adults with hypertension could not be attributed to individual nutrients, but the interactions of multiple nutrients. Most previous studies focused on a single nutrient might have overestimated or underestimated the actual impact of nutrients on mortality [12, 13, 53]. Recently, researchers have begun to look at the interaction of nutrients along with people’s improved knowledge about nutrients. A study from NHANES 2003–2005 analyzed the effects of circulating vitamins’ co-exposure (vitamin A, D, E, C, B12 and B9) with all-cause, cardiovascular and cancer mortality risk, their results found the higher vitamin D was significantly associated with reduced mortality risk [54]. The study of dietary iron and vitamins (including vitamin A, B2, B6, C, E, and folic acid) in association with mortality found their interactions on mortality, the dietary intakes of iron can affect the relationship between vitamins and mortality [21]. These findings suggested we might should focus more on overall patterns of nutrients, which should be more significantly associated with mortality compared with individual nutrients. And the contribution of each of the nutrients to the mortality risk reduction might vary. Vitamins, dietary fiber and minerals, as essential nutrients for human beings, cannot be generated in vivo and must be achieved through daily diet, but until now, no data on the association of holistic intake of dietary vitamins, dietary fiber and minerals with mortality is available. Considering synergistic and cumulative effects of vitamins, dietary fiber and minerals, the present study analyzed the interaction of nutrients within overall deficiency profiles on mortality risk. Our results supported different mortality risk was found in different nutrients deficiency pattern.

There are also some limitations in the study. The data of nutrients intake was acquired from 24-h dietary recall interviews, which might cause self-reports desirability or memory bias. Moreover, extrapolating these findings to bloodstream nutrient levels could potentially lead to inaccurate conclusions and inappropriate dietary recommendations. Besides, the intake of nutrients was only obtained at baseline without assessing the impact of these changes on mortality risk. The studied population consisted of participants with hypertension aged 60 or over, we are not sure if the same conclusions apply to other age and disease groups. Our study based on these nutrient minimum daily intake recommendations, thus might be not prove that the relationship between these nutrients patterns and mortality risk when exceeding these nutrients minimum daily intake recommendations. Finally, some other potential excluded confounding might have influence on the results. Despite its limitations, this is the first study to classify dietary nutrients patterns and analyze these association with mortality risk as far as we know, based on a large nationally-representative sample of older adults with hypertension. Also, Using LCA to classify the dietary nutrients patterns can be considered the advantage of the study, LCA contributed to assess the interactions of various dietary nutrients and analyze them as a whole entity, instead of evaluating individual relationships among nutrients.