Overweight Women Found to be Missing Key Micronutrients
How does one know if they are eating properly? A common approach involves maintaining a food diary and using food databases. To be meaningful, accurate reporting of serving sizes is required. How much butter was on my sandwich? Was it combined with full-fat mayonnaise or a low-fat alternative? Was I physically active today? How many steps did I take today? How many flights of stairs? It can be done, successfully.
Tracking micronutrient status is even more difficult. Why? When it comes to monitoring our balance between physical activity and calorie intake, we have bathroom scales. Similarly, we need something that measures micronutrient concentrations in blood to have an accurate assessment of micronutrient status.
Kabat and colleagues studied blood antioxidant concentrations measured repeatedly over 12.8y in 2,672 women participating in the Women’s Health Initiative (WHI). Serum antioxidant concentrations were generally lower in overweight and obese women (lower Body Mass Index, BMI). Carotenoid concentrations were higher in those without diabetes or metabolic syndrome, women who reported being more physically active, never smoked, and used vitamin supplements. These findings are relevant for 2 reasons, it provides evidence that: 1) obesity co-exists with hidden hunger, insufficient intake of micronutrients to maintain optimal blood and tissue antioxidant concentrations, and 2) health consequences of being overweight and obesity may be a reflection of low (insufficient) micronutrient status.
As an example, vitamin E is found naturally in 8 forms. Alpha-tocopherol is the only form recognized to meet human requirements. The liver metabolizes and excretes the other forms so their blood concentrations are lower. Kabat and colleagues report significantly higher γ-tocopherol concentrations in obese women and 41% higher in non-supplement users. The Coronary Artery Risk Development in Young Adults (CARDIA) study also found opposing effects of α- and γ-tocopherol with α-tocopherol helping to maintain normal lung function. Higher γ-tocopherol concentrations may partially reflect a low α-tocopherol intake.
Fortunately, absolute serum α-tocopherol concentrations (means) from the Women’s Health Initative have been reported. Baseline α-tocopherol concentrations among ~1,000 women ranged between 15-18.6 µg/mL (34-43 µM). 50% of women in the WHI had serum α-tocopherol concentrations below 31.3 µmol/L, lower than the baseline serum concentrations reported in most vitamin E RCTs. Indeed, nationally representative data finds 82% of US women have α-tocopherol concentrations below 30 µM if they don’t use dietary supplements.
Low vitamin E intake and consequent low serum α-tocopherol concentrations are associated with increased risk of hip fracture in elderly men and women. In men, higher serum α-tocopherol concentrations are associated with a decreased risk of developing prostate cancer, especially among smokers.
Our national dialogue should not be focused exclusively on body weight and energy balance. It is time to develop new technologies and apply them to measure micronutrient status. Until individuals know their micronutrient status, dietary guidance is being given as if wearing a blindfold. The most prudent advice is to consume the RDA. And remember, there is no danger in using a multivitamin-mineral supplement.
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