Adult-type hypolactasia is not a predisposing factor for the early functional and structural changes of atherosclerosis: the Cardiovascular Risk in Young Finns Study

Longitudinal prospective anthropometric evaluation in Caucasian prepubertal children with lactose intolerance

Introduction

The health consequences of lactose intolerance remain unclear. We studied the association of lactose intolerance with growth in children.

Methods

In this prospective case-control study, we compared Caucasian prepubertal children with lactose intolerance (LI) [n = 30, median age = 7.87 years (3.00-12.75)] to healthy controls [(n = 75, median age = 2.25 years (2.00-7.25)]. A lactose tolerance test was performed for lactose intolerance diagnosis. The gastrointestinal symptom score was administered at baseline and after a lactose-free diet for a median period of 9.0 months [range 5%-95% (6.0-24.0)]. The anthropometric parameters were measured at baseline and follow-up. All the anthropometric data were converted into standard deviation scores (SDS). A linear regression model was used to investigate the association of lactose intolerance with growth parameters.

Results

We found no difference in height velocity SDS between the LI and control groups [SDS difference (95% CI): 0.52 (-1.86 to 2.90)]. In addition, we found a significant reduction in the clinical score of the LI group after a lactose-free diet [median (5%-95%): 7.5 (4.0-15.0) and 3 (0.0-8.0); p-value <0.001].

Conclusions

The LI group exhibited no difference in height velocity compared with the control group. Nonetheless, due to the small sample size, the results on the anthropometric profile of the LI group require careful interpretation. More large-scale studies in the pediatric population are required to better understand the association of LI with anthropometric and metabolic profiles.

Anthropometric and metabolic profile of children with gene polymorphisms for primary lactose intolerance

Primary lactose intolerance is caused by a genetically programmed loss in lactase production after 5-6 years of age. Milk and dairy products are often incriminated as a cause of gastrointestinal symptoms. Recent studies show that lactase persistence in adult life correlates with higher anthropometric indexes and an altered metabolic profile. We aimed to assess whether the presence of gene polymorphisms for primary lactose intolerance has an influence on the anthropometric and metabolic profile of children. We conducted a cross-sectional study, recruiting consecutive children evaluated at the 2nd Pediatric Clinic, Timisoara from May to August 2016. We enrolled 87 children aged 6-17 years [mean age 10.64±3.51 years; 45 (51.72%) girls]. Subjects were asked to complete an analogue visual scale of symptoms. We measured weight, height, blood pressure and calculated body mass index. The metabolic profile included fasting blood glucose, triglycerides and HDL cholesterol levels. We used strip genotyping to identify gene polymorphisms for primary lactose intolerance. According to the results, our study population was grouped into lactose tolerant (n=42) and lactose intolerant (n=45) groups. No differences were found in regards to weight, height, body mass index and blood pressure between the two study groups. Glucose, triglycerides and HDL cholesterol were similar in the lactose intolerant and lactose tolerant children. The presence of gene polymorphisms for primary lactose intolerance did not influence the children's anthropometric and metabolic profile.

The Eurasian lactase persistence variant LCT-13910 C/T is associated with vitamin D levels in individuals living at high latitude, more so than exposure to sunlight

Rapid selection of a genetic variant that confers continuous life-long lactase production in Europeans (LCT-13910 C/T) has been attributed to the advantages of acquiring nutrients from consuming milk without the disadvantages of lactose malabsorption. Individuals with this genetic lactase persistence (LP) variant generally consume more milk and have been shown to have higher levels of serum vitamin D. Vitamin D is the principal regulator of Ca absorption and its synthesis in skin is dependent on UVB exposure. The primary aim of the present study was to compare serum vitamin D concentrations with LP variant and to control for UVB exposure. Data from over 100 000 individuals living in Norway, a country with low UVB exposure, was retrospectively retrieved for comparison of genetic LP variant, serum 25-hydroxyvitamin D (25(OH)D) concentration and the time of year when serum samples were taken. For comparison, a similar analysis was performed with a natural dairy micronutrient, namely vitamin B₁₂. It was found that individuals with the genetic LP variant had considerably higher levels of serum 25(OH)D (P < 2 × 10^-16, Cohen's d = 0·73) but lower levels of vitamin B₁₂ (P < 2 × 10^-16, Cohen's d = 0·11), compared with genetic lactase non-persistent individuals, even when controlled for seasonality, age and sex. The difference in serum 25(OH)D levels did not diminish in summer months, showing the role of vitamin D in LP variant selection in areas of low UVB irradiation. LP variant selection advantage through acquiring another dairy micronutrient, vitamin B₁₂, was not observed.

Gene-Dairy Food Interactions and Health Outcomes: A Review of Nutrigenetic Studies

Each person differs from the next by an average of over 3 million genetic variations in their DNA. This genetic diversity is responsible for many of the interindividual differences in food preferences, nutritional needs, and dietary responses between humans. The field of nutrigenetics aims to utilize this type of genetic information in order to personalize diets for optimal health. One of the most well-studied genetic variants affecting human dietary patterns and health is the lactase persistence mutation, which enables an individual to digest milk sugar into adulthood. Lactase persistence is one of the most influential Mendelian factors affecting human dietary patterns to occur since the beginning of the Neolithic Revolution. However, the lactase persistence mutation is only one of many mutations that can influence the relationship between dairy intake and disease risk. The purpose of this review is to summarize the available nutrigenetic literature investigating the relationships between genetics, dairy intake, and health outcomes. Nonetheless, the understanding of an individual’s nutrigenetic responses is just one component of personalized nutrition. In addition to nutrigenetic responses, future studies should also take into account nutrigenomic responses (epigenomic, transcriptomic, proteomic, metabolomic), and phenotypic/characteristic traits (age, gender, activity level, disease status, etc.), as these factors all interact with diet to influence health.

Association of lactase persistence genotype with milk consumption, obesity and blood pressure: a Mendelian randomization study in the 1982 Pelotas (Brazil) Birth Cohort, with a systematic review and meta-analysis

Background: Milk intake has been associated with lower blood pressure (BP) in observational studies, and randomized controlled trials suggested that milk-derived tripeptides have BP-lowering effects. Milk intake has also been associated with body mass index (BMI). Nevertheless, it is unclear whether increasing milk consumption would reduce BP in the general population.

Methods: We investigated the association of milk intake with obesity and BP using genetically-defined lactase persistence (LP) based on the rs4988235 polymorphism in a Mendelian randomization design in the 1982 Pelotas (Southern Brazil) Birth Cohort. These results were combined with published reports identified through a systematic review using meta-analysis.

Results: In the 1982 Pelotas Birth Cohort, milk intake was 42 [95% confidence interval (CI): 18; 67) ml/day higher in LP individuals. In conventional observational analysis, each 1-dl/day increase in milk intake was associated with −0.26 (95% CI: −0.33; −0.19) kg/m² in BMI and −0.31 (95% CI: −0.46; −0.16) and -0.35 (95% CI: −0.46; −0.23) mmHg in systolic and diastolic BP, respectively. These results were not corroborated when analysing LP status, but confidence intervals were large. In random effects meta-analysis, LP individuals presented higher BMI [0.17 (95% CI: 0.07; 0.27) kg/m²] and higher odds of overweight-obesity [1.09 (95% CI: 1.02; 1.17)]. There were no reliable associations for BP.

Conclusions: Our study supports that LP is positively associated with obesity, suggesting that the negative association of milk intake with obesity is likely due to limitations of conventional observational studies. Our findings also do not support that increased milk intake leads to lower BP.

Milk intake is not associated with ischaemic heart disease in observational or Mendelian randomization analyses in 98,529 Danish adults

BACKGROUND

Observationally, reports on the association between milk intake and risk of ischaemic heart disease (IHD) and myocardial infarction (MI) have produced conflicting results; and no previous large-scale study using the lactase persistent/non-persistent LCT-13910 C/T genotype as a largely unconfounded proxy for milk intake free of reverse causation has been conducted. We tested the hypothesis that milk intake observationally and genetically through the LCT-13910 C/T genotype is associated with risk of IHD and MI in a Mendelian randomization design.

METHODS

We included 98,529 White individuals of Danish descent, aged 20-100 years, from three studies of the general population. Information on IHD (N = 10,372) and MI (N = 4188) were obtained from national Danish registries. First, we investigated observational associations between milk intake and incident IHD and MI. Second, we confirmed the association between the rs4988235 genetic variant LCT-13910 C/T, associated with lactase persistence/non-persistence, and milk intake. Finally, we tested whether LCT-13910 C/T genotype was associated with risk of IHD and MI as well as with cardiovascular risk factors.

RESULTS

During a mean follow-up time of 5.4 years, the observational hazard ratio for a 1 glass/week higher milk intake was 1.00 [95% confidence interval (CI): 1.00,1.01] for both IHD and MI. Median milk intake was 3 glasses/week (interquartile range: 0-7) in lactase CC non-persistent individuals compared with 5 glasses/week (0-10) in lactase TC/TT persistent individuals (P = 3*10(-60)). In the dominant genetic model comparing lactase TC/TT persistent individuals with lactase CC non-persistent individuals, the odds ratio was 1.00 (0.92,1.09) for IHD and 0.96 (0.84,1.09) for MI. Finally, in the dominant genetic model genotype was not associated convincingly with plasma levels of total cholesterol, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, triglycerides or glucose, nor with blood pressure.

CONCLUSION

Milk intake was not associated with risk of IHD or MI, observationally or genetically.

Milk intake is not associated with low risk of diabetes or overweight-obesity: a Mendelian randomization study in 97,811 Danish individuals

BACKGROUND

High dairy/milk intake has been associated with a low risk of type 2 diabetes observationally, but whether this represents a causal association is unknown.

OBJECTIVE

We tested the hypothesis that high milk intake is associated with a low risk of type 2 diabetes and of overweight-obesity, observationally and genetically.

DESIGN

In 97,811 individuals from the Danish general population, we examined the risk of incident type 2 diabetes and of overweight-obesity by milk intake observationally and by LCT-13910 C/T genotype [polymorphism (rs4988235) upstream from the lactase (LCT) gene], where TT and TC genotypes are associated with lactase persistence and CC with nonpersistence.

RESULTS

Observationally for any compared with no milk intake, the HR for type 2 diabetes was 1.10 (95% CI: 0.98, 1.24; P = 0.11), whereas the OR for overweight-obesity was 1.06 (1.02, 1.09; P = 0.002). Median milk intake was 5 glasses/wk (IQR: 0-10) for lactase TT/TC persistence and 3 (0-7) for CC nonpersistence. Genetically for lactase TT/TC persistence compared with CC nonpersistence, the OR was 0.96 (0.86, 1.08; P = 0.50) for type 2 diabetes and 1.06 (1.00, 1.12; P = 0.04) for overweight-obesity. In a stratified analysis for type 2 diabetes, corresponding values in those with and without milk intake were 0.88 (0.76, 1.03; P = 0.11) and 1.35 (1.07, 1.70; P = 0.01) (P-interaction: 0.002), whereas no gene-milk interaction on overweight-obesity was found. For a 1-glass/wk higher milk intake, the genetic risk ratio for type 2 diabetes was 0.99 (0.93, 1.06), and the corresponding observational risk was 1.01 (1.00, 1.01). For overweight-obesity, the corresponding values were 1.01 (1.00, 1.02) genetically and 1.00 (1.00, 1.01) observationally.

CONCLUSIONS

High milk intake is not associated with a low risk of type 2 diabetes or overweight-obesity, observationally or genetically via lactase persistence. The higher risk of type 2 diabetes in lactase-persistent individuals without milk intake likely is explained by collider stratification bias.

The lactase persistence genotype is associated with body mass index and dairy consumption in the D.E.S.I.R. study

OBJECTIVE

The T allele of a functional polymorphism (rs4988235: LCT-13910 C>T), close to the lactase gene, correlates with lactase persistence (LP) in adults. The LP genotype (TT+TC) has been associated with a higher BMI in European populations in cross-sectional studies. In the French D.E.S.I.R. cohort, a high consumption of dairy products was associated with a lower body weight gain over 9-years, and with a lower incidence of high plasma glucose levels and/or the metabolic syndrome. Our aim was to test in this study, the association of rs4988235 with BMI and related metabolic diseases, in interaction with dairy product consumption.

METHODS

Among 5212 subjects from D.E.S.I.R., 3575 Caucasians born in mainland France were genotyped and followed over 9years.

RESULTS

Those with the LP genotype (frequency: 78.5%) had a higher dairy product consumption, at inclusion and at year-9 (P<0.001). They also had a higher BMI at both time points (difference=0.3kg/m(2), P=0.05), but this effect was restricted to medium/high dairy product consumers (difference=0.5kg/m(2), P=0.006). This genotype was also associated with the metabolic syndrome (IDF definition), but this association disappeared after adjustment for BMI. In the whole population, the C allele was associated with a higher prevalence of impaired fasting glycemia and/or type 2 diabetes.

CONCLUSIONS

The lactase persistence genotype was shown to be associated with a higher BMI in a longitudinal study, mainly in those consuming high amounts of dairy products. The association of the C allele, responsible for lactase non-persistence, with the risk of hyperglycemia needs to be replicated.

Adult-type hypolactasia and calcium intake in polycystic ovary syndrome

OBJECTIVE

Adult-type hypolactasia (ATH) is related to lower calcium and milk intake, which might be associated with obesity and metabolic disturbances. Women with polycystic ovary syndrome (PCOS) frequently suffer from metabolic disturbances including central obesity. We aimed to examine the association of ATH and calcium intake with anthropometric, metabolic and endocrine parameters in a cohort of PCOS and control women.

DESIGN

Metabolic, endocrine and anthropometric measurements and oral glucose tolerance tests were performed in 504 PCOS and 366 control women. Genotyping of ATH, defined by the -13910 variant of the MCM6 gene, was performed. Calcium intake was assessed by questionnaires.

RESULTS

Adult-type hypolactasia was more prevalent in PCOS women (29·8%) than in controls (23·5%) (P = 0·040). PCOS women with ATH had higher waist-to-hip ratio (WHR) (0·80 [0·75-0·88] vs 0·78 [0·73-0·85], P = 0·046), glucose 2 h (5·28 [4·57-6·33] mmol/l vs 5·67 [4·68-6·78] mmol/l, P = 0·037), HbA1c (5·2 [5·0-5·4]%vs 5·1 [5·0-5·3]%, P = 0·009), parathyroid hormone (3·72(2·91-4·86] pmol/l vs 3·61 [2·94-4·63] pmol/l, P = 0·030) and Ferriman-Gallwey-Scores (FG Scores) (7 [3-12] vs 4 [1-9], P = 0·002) and lower 25(OH)D levels (54·4 [35·2-80·6] nmol/l vs 68·4 [49·7-89·4] nmol/l, P < 0·001) than PCOS women without ATH. The association of 25(OH)D and FG-Scores with ATH remained significant in age-, BMI- and WHR-adjusted analyses. PCOS women within the highest quartile of calcium intake had significantly lower testosterone (P = 0·023) and androstenedione (P = 0·032) and significantly higher high-density lipoprotein (HDL) levels (P = 0·035) than PCOS women with lower calcium intake.

CONCLUSION

Our results indicate an association of ATH with PCOS susceptibility. Moreover, ATH might influence WHR, HbA1c and FG-Scores as well as 25(OH)D levels. Higher calcium intake was associated with lower androgens and higher HDL levels.

Association of the LCT-13910C>T polymorphism with obesity and its modulation by dairy products in a Mediterranean population

The -13910C>T polymorphism (rs4988235) upstream from the lactase (LCT) gene, strongly associated with lactase persistence (LP) in Europeans, is emerging as a new candidate for obesity. We aimed to analyze the association of this polymorphism with obesity-related variables and its modulation by dairy product intake in an elderly population. We studied 940 high-cardiovascular risk Spanish subjects (aged 67 ± 7 years). Dairy product consumption was assessed by a validated questionnaire. Anthropometric variables were directly measured, and metabolic syndrome-related variables were obtained. Prevalence of genotypes was: 38.0% CC (lactase nonpersistent (LNP)), 45.7% CT, and 16.3% TT. The CC genotype was not associated with lower milk or dairy product consumption in the whole population. Only in women was dairy intake significantly lower in CC subjects. The most important association was obtained with anthropometric measurements. CC individuals had lower weight (P = 0.032), lower BMI (29.7 ± 4.2 vs. 30.6 ± 4.2 kg/m(2); P = 0.003) and lower waist circumference (101.1 ± 11.8 vs. 103.5 ± 11.5 cm; P = 0.005) than T-allele carriers. Obesity risk was also significantly higher in T-allele carriers than in CC individuals (odds ratio (OR): 1.38; 95% confidence interval (CI): 1.05-1.81; P = 0.01), and remained significant even after adjustment for sex, age, diabetes, physical activity, and energy intake. However, in subgroup analysis, these associations were found to be significant only among those consuming moderate or high lactose intakes (>8 g/day). No significant associations with lipids, glucose, or blood pressure were obtained after adjustment for BMI. In conclusion, despite not finding marked differences in dairy product consumption, this polymorphism was strongly associated with BMI and obesity and modulated by lactose intake in this Mediterranean population.