This study shows significant positive associations between a meat, processed meat, and french fries dietary pattern and allostatic load score, blood pressure and waist circumference among Puerto Rican older adults. Additionally, the highest quintile of the meat and french fries pattern increased the odds of high allostatic load, low DHEA-S and high HbA1c; a significant trend toward higher odds of elevated blood pressure was also observed. Following a traditional pattern of rice, beans and oil was not associated with allostatic load; only significant trends for lower HDL-C and protection against high norepinephrine were observed across increasing quintiles of this pattern. Similarly, a sweets, sugared beverages, and dairy desserts pattern was not associated with allostatic load in participants without diabetes; however, these participants showed significant trends for lower norepinephrine, epinephrine, HDL-C and HbA1c across increasing quintiles of the pattern.
An association between high consumption of the traditional pattern and metabolic syndrome, as well as lower HDL-C was previously reported (3
). Here, the same trend for lower HDL-C was observed, but not with the cumulative measure of allostatic load, suggesting that other components of allostatic load may counterbalance the influence of HDL-C. Indeed, results showed that consumption of the traditional pattern had a protective association for high norepinephrine. One study in men ages 43–85 y showed an inverse association between norepinephrine and energy-adjusted carbohydrate consumption (21
), which is consistent with the findings in this study when considering the large energy contribution of rice to the traditional pattern (3
). Increases in blood sugar due to excess intake of dietary carbohydrate may prevent the release of norepinephrine, which is secreted under low blood sugar conditions, among other triggers.
Noel et al
. noted that the high intake of rice in participants following the traditional pattern may contribute to the observed lower HDL-C for those on Q5 of the pattern, given the high glycemic index of this food; this parameter may drive the association of the pattern with metabolic syndrome. The opposing health effects of the traditional pattern –unfavorable associations with HDL-C and metabolic syndrome, but beneficial with norepinephrine – may be due to the other types of foods that comprise it. Beans and most mono and polyunsaturated oils, may exert a protective effect (22
). Specific food and nutrient analysis may help differentiate the role of individual components of the pattern on these outcomes. Furthermore, as high urinary norepinephrine may indicate stress, anxiety or depression (24
), it may be possible that participants on the Q1 of the traditional pattern have other risk factors and lifestyles associated with those conditions that drive the observed association with this catecholamine. Future studies should consider the relationship between psychosocial factors and diet and their influence on physiological markers.
The previous study on dietary patterns in Puerto Ricans did not find an association between the meat, processed meat, and french fries pattern and metabolic syndrome, but did observe higher blood pressure and waist circumference for those in the highest quintile of this pattern. Similar associations with those individual parameters were observed here; in addition, significant associations with low DHEA-S, high HbA1c, and high allostatic load were observed. The observation that each of the individual parameters of allostatic load were also significantly associated with the pattern and had the same positive direction across quintiles, strengthens the hypothesis that higher intake of this pattern is likely detrimental to overall allostasis. Others have reported similar positive associations between meat, potatoes and sweets intake and increases in HbA1c in adult women (25
), between poultry, potatoes and processed meat intake and 5-y gain in waist circumference in middle-aged women (26
), and between red meat intake and high blood pressure in adults aged 40–59 y (27
). To date, there are no reports of associations between dietary patterns and allostatic load or physiological dysregulation. The associations between meat, processed meat and french fries with several metabolic conditions, such as type 2 diabetes, CVD and stroke have been well established (28
). Meat tends to be high in cholesterol and total and saturated fat, processed meats are usually preserved with high concentrations of salt, and french fries tend to be cooked with saturated or trans fat and have added salt. The higher salt and fat content of Q5 of this pattern may contribute to the observed trend with higher blood pressure and waist circumference. Also, as iron overload is correlated with higher HbA1c (30
), the potential mediating effect of iron intake, through higher meat consumption, on this parameter should be considered. Nevertheless, this study shows that diets high in meat, processed meat and french fries may deregulate multiple physiological parameters, which are subsequently associated with increased likelihood of metabolic and non-metabolic outcomes in this population (7
). As with the traditional pattern, specific food and nutrient analysis, particularly for types of fat and for meat source and type, is warranted.
As opposed to metabolic syndrome, which is comprised of cardio-metabolic parameters only, allostatic load score includes neuroendocrine primary parameters involved in the hypothalamic-pituitary-adrenal response to stress. This study showed increases in the likelihood of one of these primary biomarkers, low DHEA-S, an androgen produced and secreted mainly by the adrenal cortex, for Q5 of the meat and french fries pattern. Several studies have found variations in DHEA-S according to dietary intake. Analyzing women who served as controls in a nested case-control study from the Nurses’ Health Study, Holmes et al
. found that, although there was no significant variation in the percentage difference from substituting 5% of energy from animal vs. vegetable fat, DHEA-S concentration was inversely associated with polyunsaturated fatty acids (PUFA) intake but positively associated with monounsaturated fatty acids (MUFA) (31
). In a short-term intervention, Remer et al
. observed elevated plasma DHEA-S on a low-protein lactovegetarian diet but not on a moderately protein-rich diet or a protein-rich diet (32
), which agrees with the results of this study. In a separate short-term intervention, moderate increases in daily protein intake did not affect plasma DHEA-S concentration (33
). The differences in composition of the diets reported in these studies and the meat and french fries pattern reported here make it difficult to draw comparisons; however, these studies suggest that high fat content, rather than protein, in the meat and french fries pattern may stimulate the association with DHEA-S.
Animal meat may have natural or added hormones that could influence sex hormone production and other cellular and physiological processes in humans that consume it (34
). Also, cholesterol is a precursor for several androgens, and high cholesterol content in meat may influence DHEA-S production, but no studies have confirmed this. In a cross-sectional study of postmenopausal Australian women by Brinkman et al
., significant negative associations were observed between total red and fresh red meat consumption and circulating concentrations of sex-hormone binding globulin, but not with DHEA-S; none of the types of fat nor cholesterol intake were associated with sex hormones (36
). Finally, low DHEA-S may indicate adrenal cortex dysfunction, and has been observed in people with cancer, CVD, Alzheimer’s disease, other age-related and immune function disorders (37
). Several studies have found that diets containing meat and/or high amounts of fat are associated with higher prevalence and incidence of some of these conditions (38
) and it may be possible that these factors confound analysis. As DHEA-S is a precursor for other androgens involved in the development of metabolic syndrome, insulin resistance and obesity (41
), maintaining normal levels of this hormone may be critical in preventing further physiological dysregulation.
The sweets, sugared beverages and dairy desserts pattern was associated with lower norepinephrine, epinephrine, HDL-C and HbA1c, after excluding participants with diabetes. Other studies have shown that individuals with diabetes, when aware of their status, reduce their sugar and carbohydrate intake, while modifications in fat and protein intake have been inconsistent (42
). Meat intake has been reported to increase among women with diabetes (44
); however this was not observed in this study. While an inverse trend between a sweets pattern and the two neuroendoencrine markers has not been reported to date, their role in increasing blood glucose during times of stress may support a mechanistic response to sweets and sugar intake. Repeated increases in blood glucose after frequent or high sugar intake may disrupt the release of catecholamines in order to prevent further blood glucose increases. An intervention of carbohydrate-rich meals given over 24 h to older men showed an overall increase in norepinephrine but a marked blunting of plasma epinephrine, suggesting an age-related dysregulation in the adrenomedullary response to this macronutrient (45
). This would partly agree with the results shown here; further studies on sugar/sweets intake and catecholamine response are needed.
Other studies have previously reported the association reported here between high intake of a sweets and sugared drinks pattern and lower HDL-C concentration (3
). However, the inverse association between the pattern and HbA1c, a marker of blood glucose control, was unexpected, even after restricting the study to participants without diabetes. While carbohydrate intake has not been associated with HbA1c in the National Health and Nutrition Examination Survey III (47
), higher intake of this macronutrient predicted increases in HbA1c over ten years in British adults (48
). A few studies have reported higher HbA1c adults without diabetes who consumed more saturated fat or a lower polyunsaturated fat–to–saturated fat ratio (49
). Yet, there were no differences in saturated fat content between Q1 and Q5 of the sweets pattern in this sample, while PUFA intake was lower in Q5 (3
A limitation of this study is its cross-sectional nature, which limits ability to attribute a causal direction between the patterns and the physiological outcomes. Reverse causation, where participants with well-regulated blood glucose (lower HbA1c) consume more sweets and sugared beverages and desserts, may explain the results observed for the sweets pattern. Additionally, it is possible that people alter their dietary habits regarding meat and french fries in response to stress or physiologically dysregulated parameters. Longitudinal data analysis may clarify the observed associations. It should also be noted that the analytical method used to derive the patterns allows for comparisons within a pattern only (low to high adherence), not for comparisons across patterns. Another limitation is that allostatic load is still a fairly new concept that, although increasingly recognized in health-related research, must be systematically defined to allow comparisons between studies. Romero et al. noted its weaknesses, mainly regarding its use of energy balance, a factor that is inconsistent and hard to measure, to explain how organisms cope with stress (51
). Yet, they also point out the strengths and validity of the concept, and state that the limitations may not apply to all fields of study. As this study does not entail the stress coping mechanism, but rather uses allostatic load as a marker of dysregulation, its application may be considered appropriate. Moreover, these results add evidence of its utility in this type of nutritional studies and support further consideration of a standardized definition.