In the news: Low Vitamin D, Overweight and Back Pain; Cholesterol Controversy is Back…

Overweight with Back Pain? Vitamin D Levels

Chronic back pain can really limit a person's activities and affect their quality of life. Back pain is, in fact, the greatest cause of disability worldwide, and treatment options are limited.

Vitamin D deficiency and overweight are each risk factors for lower back pain in both men and women. There is also a connection between obesity and vitamin D status. Compared to non-obese individuals, lower levels of serum vitamin D are more common in those who carry around too much body fat.

People who have a body mass index of 30 or more may need larger than usual intakes of vitamin D to achieve serum levels that are comparable to those found in normal weight individuals. One reason appears to be that the greater amount of subcutaneous fat (the jiggly fat just under the skin) stores more of the vitamin, and alters its release into the circulation where it can do its job.

Australian researchers recently studied (1) overweight and obese people with lower back pain and low vitamin D blood levels (less than 50 nmol/L). Study participants were given high amounts of supplemental vitamin D or placebo over a 16-week period.

After accounting for other factors that can affect back pain or vitamin D levels, the investigators found that 20 participants who had very low blood levels (less than 30 nmol/L at the study’s start) experienced a greater reduction in back pain disability scores compared to those given a placebo. The authors suggest that increasing very low vitamin D blood levels can improve back pain in the overweight and obese.

The Egg and Cholesterol Riddle

Whether eating dietary cholesterol, including eggs, is linked to cardiovascular disease (CVD) and death has been debated for decades. Earlier US Dietary Guidelines urged Americans to eat less than 300 mg of dietary cholesterol daily, while the 2015-2020 US Dietary Guidelines are more relaxed and omit a daily limit on cholesterol intake.

Now, a large-scale analysis from Northwestern University has made headlines with findings that eating 300 mg of cholesterol daily is associated with a 17% higher risk of CVD and that eating 3-4 eggs weekly is linked to a 6% higher risk of CVD (2). The study does have limitations. For example, cholesterol intake was based on a single snapshot of the diet in time, and diets can change over time. However, the study was a comprehensive review and analysis that is getting a lot of attention.

At the same time, another large study (3) from the University of Sydney reports that eating 2-4 eggs weekly at baseline is associated with a 62% lower risk of late stage AMD compared to people eating 1 or less eggs weekly after 15 years of follow-up. Egg yolks contain bioavailable lutein and zeaxanthin as well as about 186 mg of cholesterol per 1 large egg.

Avoid Eggs or Eat Them in Moderation?

The first thing to keep in mind is that dietary intake of cholesterol from eggs, red meat, processed meat and high-fat dairy like butter and whipped cream, affect individuals differently. Some people can consume eggs regularly and very little is gets into the blood stream, while others have blood cholesterol that is more responsive to the amount of cholesterol consumed. In other words, genetic and metabolic factors interact to influence whether the amount of dietary cholesterol consumed impacts the amount of cholesterol in blood.

It’s a good idea to know your blood cholesterol numbers (e.g. total and LDL cholesterol), and to work with your own physician to decide whether curtailing dietary cholesterol is right for you. In the meantime, eating eggs in moderation – perhaps 2 per week – seems reasonable, particularly if dietary cholesterol overall is not excessive.

References

1. Brady SRE, et al. Vitamin D supplementation may improve back pain disability in vitamin D deficient and overweight or obese adults. J Steroid Biochem Mol Biol. 185:212-217, 2019.
2. Zhong VW, et al. Associations of dietary cholesterol or egg consumption with incident cardiovascular disease and mortality. JAMA. 321:1081-1095, Mar, 2019.
3. Gopinath B, et al. Consumption of eggs and the 15-year incidence of age-related macular degeneration. Clin Nutr. Epub March 16, 2019.