Dr. Ron’s Research Review – May 2, 2018

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This week’s research review focuses on prenatal food cravings.

The presence of cravings during pregnancy is a common phenomenon across different cultures, but the types of foods desired and the adverse impact of cravings on health may be culture-specific. (Orloff and Hormes, 2014)
In western societies a high frequency of heartburn, nausea and vomiting occur during pregnancy. Evidence suggests steroid hormones modulate gastrointestinal transit time and plasma peptide hormones, while peptide hormone modulated food intake and preferences. Since diurnal and episodic release of steroid and peptide hormones occur, it is postulated that heartburn and other digestive dysfunction during pregnancy are associated with elevated steroid and peptide (beta-endorphin, NPY) hormone interaction with innate biological rhythms controlling the gastrointestinal tract. Aversions and preferences of pregnant women while anecdotal probably represent physiological requirements. Thus pickles, candy or aversions to coffee or alcohol may be equated with an unconscious relief from heartburn and changes in taste and water balance. (Hill, 1990)
Researchers once thought that pregnancy was a period of total immunosuppression, but that may not be true. The woman's responses to these threats have been hypothesized to serve as ‘behavioral immune responses’ that aid the mother in resisting pathogen infection and toxin ingestion. Food cravings are considered an additional tool that assists in pathogen avoidance. This study found women were most likely to experience cravings for fruits. Interestingly, cravings focused on unripe mango and unripe tamarind, two items that are high in antioxidants. The sour taste may indicate vitamin C. (Placek, 2017)
Salty cravings were associated with lower risk of GDM (adjusted odds ratio 0.34, 95% CI 0.12-0.97). (Farland et al., 2015)

Dr. Ron

 


 

Articles

Early Pregnancy Cravings, Dietary Intake, and Development of Abnormal Glucose Tolerance.
            (Farland et al., 2015) Download
BACKGROUND:  Little is known about the relationships between pregnancy cravings, maternal diet, and development of abnormal glucose tolerance. OBJECTIVES:  We examined relationships of pregnancy cravings with dietary intake and risk of developing isolated hyperglycemia (IH), impaired glucose tolerance (IGT), or gestational diabetes (GDM) later in pregnancy. DESIGN/SETTING:  Among 2,022 mothers in Project Viva, a prospective birth cohort recruited from medical practices in eastern Massachusetts between 1999 and 2002, we assessed type of pregnancy craving based on self-report at mean gestation of 10.9 weeks. MAIN OUTCOME MEASURES:  The outcomes were cross-sectional dietary intake from a food frequency questionnaire and incident IH, IGT, or GDM determined by glucose tolerance screening at 26 to 28 weeks. STATISTICAL ANALYSES PERFORMED:  We used linear regression to analyze the cross-sectional relationships between pregnancy cravings and dietary intake and multinomial logistic regression to analyze the prospective relationships among pregnancy cravings and development of IH, IGT, or GDM. RESULTS:  During the first trimester, 443 (22%) women craved sweets, 225 (11%) craved salty foods, 261 (13%) craved savory foods, and 100 (4.9%) craved starchy foods. Sweet cravings were associated with increased intake of sucrose (1.9 g/day; 95% CI 0.1 to 3.7), total fat (1.5 g/day; 95% CI 0.1 to 2.9), and saturated fat (0.8 g/day; 95% CI 0.2 to 1.4); salty cravings were associated with increased fiber (0.7 servings/day; 95% CI -0.1 to 1.6); savory cravings were associated with increased n-3 fatty acids (0.10 g/day; 95% CI 0.02 to 0.17); and starchy cravings were associated with increased carbohydrates (8.0 g/day; 95% CI 0.3 to 15.7) and decreased total fat (-2.6 g/day; 95% CI -5.2 to -0.1). Salty cravings were associated with lower risk of GDM (adjusted odds ratio 0.34, 95% CI 0.12-0.97). CONCLUSIONS:  New cravings in the first trimester of pregnancy were associated with dietary intake. Craving salty foods may predict reduced risk of developing GDM, whereas craving sweet food does not appear to alter one's risk.

Pickles, peptide hormones and pregnancy: a hypothesis.
            (Hill, 1990) Download
In western societies a high frequency of heartburn, nausea and vomiting occur during pregnancy. The causes and mechanisms of these clinical symptoms remain poorly understood. Evidence suggests steroid hormones modulate gastrointestinal transit time and plasma peptide hormones, while peptide hormone modulated food intake and preferences. Since diurnal and episodic release of steroid and peptide hormones occur, it is postulated that heartburn and other digestive dysfunction during pregnancy are associated with elevated steroid and peptide (beta-endorphin, NPY) hormone interaction with innate biological rhythms controlling the gastrointestinal tract.

Pickles and ice cream! Food cravings in pregnancy: hypotheses, preliminary evidence, and directions for future research.
            (Orloff and Hormes, 2014) Download
Women in the United States experience an increase in food cravings at two specific times during their life, (1) perimenstrually and (2) prenatally. The prevalence of excess gestational weight gain (GWG) is a growing concern due to its association with adverse health outcomes in both mothers and children. To the extent that prenatal food cravings may be a determinant of energy intake in pregnancy, a better understanding of craving etiology could be crucial in addressing the issue of excessive GWG. This paper reviews the available literature to corroborate and/or dispute some of the most commonly accepted hypotheses regarding the causes of food cravings during pregnancy, including a role of (1) hormonal changes, (2) nutritional deficits, (3) pharmacologically active ingredients in the desired foods, and (4) cultural and psychosocial factors. An existing model of perimenstrual chocolate craving etiology serves to structure the discussion of these hypotheses. The main hypotheses discussed receive little support, with the notable exception of a postulated role of cultural and psychosocial factors. The presence of cravings during pregnancy is a common phenomenon across different cultures, but the types of foods desired and the adverse impact of cravings on health may be culture-specific. Various psychosocial factors appear to correlate with excess GWG, including the presence of restrained eating. Findings strongly suggest that more research be conducted in this area. We propose that future investigations fall into one of the four following categories: (1) validation of food craving and eating-related measures specifically in pregnant populations, (2) use of ecological momentary assessment to obtain real time data on cravings during pregnancy, (3) implementation of longitudinal studies to address causality between eating disorder symptoms, food cravings, and GWG, and (4) development of interventions to ensure proper prenatal nutrition and prevent excess GWG.

A test of four evolutionary hypotheses of pregnancy food cravings: evidence for the social bargaining model.
            (Placek, 2017) Download
The onset of cravings for items not typically desired is often considered a hallmark of pregnancy. Given the ubiquity of cravings, this phenomenon remains surprisingly understudied. The current study tested four hypotheses of pregnancy food cravings: behavioural immune system, nutrient seeking, resource scarcity and social bargaining. The research took place in Tamil Nadu, South India, with pregnant women residing in rural villages

 

References

Farland, LV, SL Rifas-Shiman, and MW Gillman (2015), ‘Early Pregnancy Cravings, Dietary Intake, and Development of Abnormal Glucose Tolerance.’, J Acad Nutr Diet, 115 (12), 1958-1964.e1. PubMed: 26099686
Hill, P (1990), ‘Pickles, peptide hormones and pregnancy: a hypothesis.’, Med Hypotheses, 32 (4), 255-59. PubMed: 2233414
Orloff, NC and JM Hormes (2014), ‘Pickles and ice cream! Food cravings in pregnancy: hypotheses, preliminary evidence, and directions for future research.’, Front Psychol, 5 1076. PubMed: 25295023
Placek, C (2017), ‘A test of four evolutionary hypotheses of pregnancy food cravings: evidence for the social bargaining model.’, R Soc Open Sci, 4 (10), 170243. PubMed: 29134058