Dietary acid load and mortality from all causes, CVD and cancer: results from the Golestan Cohort Study

Abstract

Given the limited studies, and controversial results on association between dietary acid load and mortality from cardiovascular disease (CVD) and cancers, we aimed to investigate this association in a large population cohort study in Middle-East, with a wide range of dietary acid load. The study was conducted on the platform of the Golestan Cohort Study (GCS), which enrolled 50,045 participants in 2004-2008. Dietary intake was assessed using a validated food frequency questionnaire (FFQ). Dietary potential renal acid load (PRAL) score was calculated from nutrient intake. Death and its causes were identified, and confirmed by two or three physicians. Cox proportional hazards regression was used to estimate HRs and 95% CIs for total and cause specific mortalities. Then, the associations were modeled using restricted cubic splines. PRAL range was -57.36 to +53.81 mEq/d for men and -76.70 to +49.08 for women. During 555,142 person-years of follow-up, we documented 6830 deaths, including 3070 cardiovascular deaths, 1502 cancer deaths and 2258 deaths from other causes. For overall deaths, in final model after adjustment for confounders, participants in the first and 5th quintiles of PRAL had a higher risk of mortality compared to the second quintile of PRAL (HR: 1.08; 95% CI:1.01-1.16 and HR: 1.07; 95% CI: 1.01-1.15, respectively); P for trend <0.05). Participants in the first and 5th quintiles of PRAL had a 12% higher risk of CVD mortality compared to the Q2 of PRAL (HR: 1.12; 95% CI: 1.01-1.25 and HR: 1.12; 95% CI: 1.01-1.26, respectively; P for trend <0.05). We found that all-cause and CVD mortality rates were higher in the lowest and highest PRAL values, in an approximately U-shaped relation (P-values for the overall association and the non-linear association of energy-adjusted PRAL with total mortality were <0.001 and <0.001, and with CVD mortality were 0.008 and 0.003, respectively). Our results highlight unfavorable associations of high acidity and alkalinity of diet with the increased total and CVD mortality risk. It may be important to consider a balanced acid-base diet as a protective strategy to prevent premature death, especially from CVD.

Association between dietary acid load and cancer risk and prognosis: An updated systematic review and meta-analysis of observational studies

“…Of these, 5 articles ( 38 – 42 ) were further eliminated because of the duplicated study population and incomplete results. The final selection yielded 10 articles ( 16 – 25 ; 7 studies for cancer risk and 3 studies for cancer prognosis; Figure 1 ) included in the meta-analysis.…”

“…Table 1 demonstrates the characteristics of the cancer prognosis studies ( 16 , 24 , 25 ), which were referred to as cohort studies. Of them, two studies were undertaken in North America ( 24 , 25 ) and one study was undertaken in Asia ( 16 ). PRAL was assessed in all the studies, whereas NEAP was applied in two studies ( 24 , 25 ).…”

“…In 2016, Fenton and Huang (15) conducted a systematic review and found only one study focused on the association between DAL and cancer risk, which suggested null results. Interestingly, several epidemiological studies have published their results in recent years, but the findings have been controversial (16)(17)(18)(19)(20)(21)(22)(23)(24)(25). For example, a large cohort study with 43,570 participants showed that consumption of high DAL food increased the risk of breast cancer (19).…”

“…Hejazi et al(16) Age, sex, BMI, smoking, alcohol, opium, wealth score, physical activity, dietary fat, carbohydrate, fiber intake, history of CVD, COPD, renal failure, diabetes Milajerdi et al(18) Age, sex, energy intake, marital status, smoking, family history of cancer, physical activity, supplement use, disease duration, high-risk residential area, history of exposure to the radiographic X-ray, history of head trauma, duration of cell phone use, history of allergy, history of hypertension, exposure to chemicals, drug use, frequent fried food intake, frequent use of barbecue, canned foods and microwave, high-risk occupation, dietary intakes of polyunsaturated fatty acids, sodium, calcium, selenium, vitamin C, vitamin E, vitamin B6, folic acid, BMIRonco et al (20) Age, residence, family history of cancer in first degree, BMI, smoking intensity, alcohol status, "Mate" intake, tea intake, energy, total fiber, total carotenoids, lignans, flavonols, glutathione, vitamin C, vitamin E, animal-based iron, total heterocyclic amines Shi et al (22) Age, sex, smoking status, history of diabetes, alcohol intake, BMI, family history of pancreatic cancer, dietary fiber, carbohydrate, energy intake from diet Nasab et al (17) Age, comorbidity, cancer family history, common ways of cooking, level of salt intake, physical activity, calcium supplement use Wu et al (24) Age at diagnosis, race/ethnicity, education level, intervention group, menopausal status at baseline, total calorie intake, alcohol intake, physical activity, BMI, number of comorbidities, tumor stage, tumor size, estrogen and progesterone receptor status, tamoxifen use, radiotherapy, chemotherapy Wu et al (25) Age at diagnosis, race/ethnicity, education level, intervention group, menopausal status at baseline, total calorie intake, alcohol intake, smoking status, pack-years, physical activity, BMI, tumor stage, tumor size, estrogen and progesterone receptor status, tamoxifen use, radiotherapy, chemotherapy women, weight at age 18 years old, number of children, length of breastfeeding, family history of breast cancer, energy intake Wright et al (23) Age, energy intake, number of years of smoking, cigarettes/day, intervention assignment BMI, body mass index; COPD, chronic obstructive pulmonary disease; CVD, cardiovascular disease; "Mate" is the name of the staple infusion in Uruguay, made from the Ilex paraguariensis herb. *A study could be awarded a maximum of one star for each item except for the item Control for important factor or additional factor.…”

Dietary Acid Load, Serum Polychlorinated Biphenyl Levels, and Mortality Following Breast Cancer in the Long Island Breast Cancer Study Project

“…On the other hand, the inverse association we observed between DAL and breast cancer mortality among women with low levels of PCBs requires further investigation. At least one recent study suggests that DAL may have a non-linear association with health outcomes [ 43 ].…”