Quote from Dr. Garrett Smith on December 14, 2018, 4:17 pm

Multiple studies, and I'm going to put them in the order they were published.  One showed an association between cod liver oil and adult asthma.  Another one by the same authors showed a significant association between cod liver oil intake, multivitamin intake, and/or those who took both, and an increase in asthma 11 years later.  What do all of these things contain?  Poison/"Vitamin A".

Relationship of fish and cod oil intake with adult asthma. (2007)

Adult consumption of cod oil had a u-shaped association with asthma, with the highest risks in those taking cod oil never and daily.

Cod liver oil intake and incidence of asthma in Norwegian adults--the HUNT study.

BACKGROUND:  Cod liver oil is an important source of vitamin D, but also contains other fat-soluble components such as vitamin A. Before 1999, the cod liver oil formula in Norway contained a high concentration of vitamin A (1000 µg per 5 ml). High vitamin A status is associated with increased risks of several chronic diseases.

OBJECTIVE:  To investigate the association between cod liver oil intake and asthma development.

METHODS:  In the Nord-Trøndelag Health Study, a total of 25 616 Norwegian adults aged 19-55 years were followed up from 1995-1997 to 2006-2008. Current analysis based on 17 528 subjects who were free of asthma and had complete information on cod liver oil intake at baseline. Cod liver oil intake was defined as daily intake ≥ 1 month during the year prior to baseline. Incident asthma was reported as new-onset asthma during the 11-year follow-up.

RESULTS:  Of the 17 528 subjects, 18% (n=3076) consumed cod liver oil daily for ≥ 1 month over the past year. Cod liver oil intake was significantly associated with incident asthma with an OR of 1.62 (95% CI 1.32 to 1.98) after adjustment for age, sex, daily smoking, physical activity, education, socio-economic status, family history of asthma, and body mass index (BMI). The positive association was consistent across age (< 40/≥ 40 years), sex (men/women), family history of asthma (yes/no) and BMI subgroups (< 25/≥ 25 kg/m(2)).

CONCLUSIONS:  Intake of cod liver oil with high vitamin A content was significantly associated with increased incidence of adult-onset asthma.

Introduction
[...] In Norway, the cod liver oil formula contained a high concentration of vitamin A (1000 µg per 5 ml) before 1999. Because of the possible adverse effect of excessive vitamin A intake on bone mineral density and fracture risk,14 it was gradually reduced to the current concentration (250 µg per 5 ml) between 1999 and 2002.15 We conducted a study among adults in Norway who participated in the Nord-Trøndelag Health Study (HUNT) in 1995–1997 and were followed up to 2006–2008, for an average of 11 years. This provided us a unique opportunity to evaluate the association between intake of cod liver oil with high vitamin A concentration and risk of adult-onset asthma.

But wait!!!  What about the nutrition gurus on the interwebz who say that cod liver oil, and ONLY cod liver oil, has the "perfect balance" of Vitamin A and Vitamin D?  Are they DEAD WRONG?  What did the Norwegians figure out that they haven't?  Seems pretty obvious to me what it was/is.

Results

[...] The cumulative incidence of asthma over the 11-year follow-up was 4.4% among people who regularly consumed cod liver oil compared with 2.9% among people who did not (table 2). After adjustment for baseline characteristics (model I), cod liver oil consumption was significantly associated with an increased incidence of asthma (OR 1.62; 95% CI 1.32 to 1.98), and the ORs were 1.51 (1.06 to 2.15) and 1.68 (1.31 to 2.16) among men and women, respectively. In addition, each 1 month daily intake of cod liver oil was significantly associated with incident asthma (table 2). After additional adjustment for vitamin D supplementation (model II) among women, the positive association of cod liver oil intake and incident asthma remained (OR 1.67; 1.29 to 2.15). In contrast to the cod liver oil findings, vitamin D supplementation was not significantly associated with incident asthma among women (OR 1.05; 0.76 to 1.44). Additional adjustment for use of multivitamins (model III) yielded an attenuated but significant OR for cod liver oil intake in the total population (table 2).

Discussion

Our study demonstrated that intake of cod liver oil was associated with an increased incidence of asthma among adults. This positive association was consistently shown in subgroups stratified by age, sex, family history of asthma and BMI.

The findings in our prospective cohort study are consistent with two previous cross-sectional studies which found a positive association between cod liver oil consumption and asthma prevalence.20 ,21

 

Intake of multivitamin supplements and incident asthma in Norwegian adults: the HUNT study

Although intake of multivitamin supplements is becoming increasingly popular, the relationship between intake of multivitamin supplements and incident asthma remains unclear. Prospective studies in adults with long-term follow-up are especially scarce. Our objective was to investigate the association between intake of multivitamin supplements and asthma development in Norwegian adults.

We followed 16 952 adult subjects from the second survey of the Nord-Trøndelag Health Study (1995–1997) up to 2006–2008, who, at baseline, were free of asthma and provided information on their intake of multivitamin supplements and cod liver oil. Regular intake of multivitamin supplements or cod liver oil was defined as daily intake for ≥3 months during the year prior to baseline. Incident asthma was defined as reported new-onset asthma after the 11-year follow-up.

Intake of multivitamin supplements only was associated with an increased odds ratio for incident asthma (OR 1.55, 95% CI 1.12–2.13) after adjustment for a number of common confounding factors (model I). Similar odds ratios were found for intake of cod liver oil only and for intake of both supplements (1.59 and 1.73, respectively).