Dairy nutrition: What we knew then to what we know now

Lactase deficiency in Russia: multiethnic genetic study

BACKGROUND

Lactase persistence-the ability to digest lactose through adulthood-is closely related to evolutionary adaptations and has affected many populations since the beginning of cattle breeding. Nevertheless, the contrast initial phenotype, lactase non-persistence or adult lactase deficiency, is still observed in large numbers of people worldwide.

METHODS

We performed a multiethnic genetic study of lactase deficiency on 24,439 people, the largest in Russia to date. The percent of each population group was estimated according to the local ancestry inference results. Additionally, we calculated frequencies of rs4988235 GG genotype in Russian regions using the information of current location and birthplace data from the client's questionnaire.

RESULTS

The attained results show that among all studied population groups, the frequency of GG genotype in rs4988235 is higher than the average in the European populations. In particular, the prevalence of lactase deficiency genotype in the East Slavs group was 42.8% (95% CI: 42.1-43.4%). We also investigated the regional prevalence of lactase deficiency based on the current place of residence.

CONCLUSIONS

Our study emphasizes the significance of genetic testing for diagnostics, i.e., specifically for lactose intolerance parameter, as well as the scale of the problem of lactase deficiency in Russia which needs to be addressed by the healthcare and food sectors.

Milk powder induced lipid peroxidation reduction using Ku Ding tea (Lactuca taiwaniana Maxim) in rats

The effects of Ku Ding tea (Lactuca taiwaniana Maxim) and milk powder on biochemical and immunological parameters of Sprague-Dawley rats were investigated and the possibility of use of Ku Ding tea to reduce physiological discomfort of drinking milk powder was assessed. Eighty rats were randomly assigned to four treatments: basal diet (control), basal diet plus whole milk powder (WM), basal diet plus Ku Ding tea (KD) and basal diet plus whole milk powder and Ku Ding tea (MK). Data was collected on animals' final body weight, hematological values, blood biochemical parameters, antioxidation parameters and immune organ weight index. Results showed that final body weight of male KD was significantly lower than that of WM. White blood cell count, monocyte count and granulocyte count of KD rats were significantly lower than those of WM. Compared to the control, single milk powder supplementation numerically increased plasma malondialdehyde. The malondialdehyde in the male KD and MK rats were lower than those in WM and control, although the differences were not significant. No significant differences were found in Na(+)K(+)-adenosine triphosphatase activity, spleen and thymus index in each group. Consumption of Ku Ding tea appeared to lower lipid peroxidation that was induced by milk powder in the rats.

Molecular mechanisms triggered by low-calcium diets

Ca is not only essential for bone mineralisation, but also for regulation of extracellular and intracellular processes. When the Ca2+ intake is low, the efficiency of intestinal Ca2+ absorption and renal Ca2+ reabsorption is increased. This adaptive mechanism involves calcitriol enhancement via parathyroid hormone stimulation. Bone is also highly affected. Low Ca2+ intake is considered a risk factor for osteoporosis. Patients with renal lithiasis may be at higher risk of recurrence of stone formation when they have low Ca2+ intake. The role of dietary Ca2+ on the regulation of lipid metabolism and lipogenic genes in adipocytes might explain an inverse relationship between dairy intake and BMI. Dietary Ca2+ restriction produces impairment of the adipocyte apoptosis and dysregulation of glucocorticosteroid metabolism in the adipose tissue. An inverse relationship between hypertension and a low-Ca2+ diet has been described. Ca2+ facilitates weight loss and stimulates insulin sensitivity, which contributes to the decrease in the blood pressure. There is also evidence that dietary Ca2+ is associated with colorectal cancer. Dietary Ca2+ could alter the ratio of faecal bile acids, reducing the cytotoxicity of faecal water, or it could activate Ca2+-sensing receptors, triggering intracellular signalling pathways. Also it could bind luminal antigens, transporting them into mucosal mononuclear cells as a mechanism of immunosurveillance and promotion of tolerance. Data relative to nutritional Ca2+ and incidences of other human cancers are controversial. Health professionals should be aware of these nutritional complications and reinforce the dairy intakes to ensure the recommended Ca2+ requirements and prevent diseases.