By: Mary Scourboutakos

Neural tube defects are a type of birth defect—affecting the brain, spine or spinal cord—that result from suboptimal folate status.
Folate is a B vitamin that’s naturally found in legumes (like chickpeas, lentils, pinto and kidney beans), seeds, leafy greens (like spinach, collard greens and romaine lettuce) and other vegetables such as asparagus, brussels sprouts and broccoli.

The problem is, people don’t eat enough of these foods. As a result, for many years, pregnant women were at risk for folate deficiency and hence, neural tube defects.

Prenatal supplements were the original solution to this problem as one of their prime ingredients is folic acid, the synthetic form of folate. However, they’re not a fool proof solution because neural tube defects form within four weeks of conception, often before women know they’re pregnant, and thus, before they start taking their supplements.

As a result, in the late 1990s folic acid was mandatorily added to white flour and enriched grain products to ensure that pregnant women would get enough folate, irrespective of whether they take a supplement.

Problem solved? Sort of…

Back in the early 1990s when discussions regarding the addition of folic acid to the food supply were taking place, it was suggested that after fortification was implemented, the dose of folic acid in prenatal supplements should be revised to prevent excessive intakes. The new problem is…the doses were never revised.

Currently, marketed prenatal supplements usually contain 1000 micrograms of folic acid, which is the daily upper limit for folic acid. Meanwhile, it’s recommended that pregnant women should consume about 400 micrograms of folic acid per day for neural tube defect prevention.

With mandatory fortification, three-quarters of a cup of cereal can provide greater than 400 micrograms of folic acid. So if you add a prenatal supplement to a bowl of cereal at breakfast, some bread at lunch, and pasta for dinner, you’re consuming a lot of folic acid!

According to Dr. Deborah O’Connor, a Professor from the University of Toronto who has spent decades studying folate and infant health, this could be a problem. She explained that in animal models, it has been shown that folate can make changes to the genes that are transcribed during development. And while similar data have not been done on humans, she said “if you’re not getting any benefit from those high levels, it would be prudent to cut back given the current status…(because) if there’s no benefit, there’s only a risk.”

From a regulatory point-of-view, she says there’s nothing stopping the industry from changing the amount of folic acid in the supplements. She suggested that the industry’s reluctance to modify the dose in prenatal supplements is probably due to inertia and the fact that “with nutrition you’re always fighting against the more is better philosophy.”

In the meantime, what should women do? In their 2015 clinical practice guidelines, the Society of Obstetrics and Gynecologists recommended a multivitamin containing 400 to 1000 micrograms of folic acid. But currently, there are no prenatal vitamins available with less than 1000. Hence, Dr. O’Connor’s recommendation is “do not use the prenatal, just use a regular multi-vitamin and maybe add a little iron.” Furthermore, she added “care must be taken to ensure vitamin A intakes do not exceed 3,000 mcg retinol activity equivalents (RAE) or 10,000 IU during pregnancy.”

Alas, it’s a classic story, you try to fix one problem, but in doing so, you create another. Hopefully prenatal supplements will be adjusted soon, but in the meantime, prudent folic acid intakes are probably a good idea.

By: Hassan S Dashti, PhD

The most popular New Years resolution by far is weight loss. People kick-start their new year on new ‘detox’ or fad diets with hopes to lose some weight or, less commonly, to adopt a healthy lifestyle, only to quit a few months later. Traffic to websites like caloriecounter.com and weightwaterchers.com hits an all time high in January! (1) People often envision January 1 of every year as an empowering and motivating moment that enables them to consider making these daring lifestyle changes. People might be less inclined to make these commitments on arbitrary dates like March 1 or October 19. With emerging evidence suggesting seasonal changes in the environment and human physiology, driven primarily by seasonal changes in sunlight and temperature, is it possible that certain start dates or seasons are more conducive to successful weight loss?

Seasonal variations have been observed for numerous communicable and non-communicable diseases (2) and both biological and behavioral traits. One of the earliest observations of seasonal variation in a disease was that of rickets, a disease resulting from vitamin D deficiency (3). Clinical observations indicated that rickets was common in spring, but rare in fall. The subsequent finding of seasonal variation in plasma 25(OH)D levels suggested that summer sunlight exposure was indeed an important determinant of vitamin D status. For more complex traits, like obesity, the seasonal etiology, if present, is likely to be multifactorial!

Successful weight loss is largely determined by the ability to reduce overall caloric intake, which depends on food availability and internal hunger cues. Living at a time where food is essentially abundant year-round in the Western world, people are typically not dealing with food shortages. For most processed foods, seasonal price variability is also absent, particularly in metropolitan areas, so people’s intakes are likely to be homogenous year-round (4,5). However, seasonal price variability of nutrient dense fruits and vegetables may limit a person’s likelihood to adhere to diets higher in fruits and vegetables. For example, strawberry prices tend to decrease through the first four months of the year and rise again from September to December. Fresh apples, on the other hand, have a fairly weak seasonal price pattern as a result of new apple varieties with later harvest dates and sophisticated storage technology. But it seems that despite the constant supply of most foods at steady prices, seasonal variation in dietary intake may exist. In the Framingham Heart Study, for example, self-reported total energy intake was 86 kcal/day higher during the fall than in the spring (6). Also, percentage of calories from carbohydrate, fat and saturated fat showed slight seasonal variation, with a peak in the spring for carbohydrate and in the fall for total fat and saturated fat intake. Of course these differences may be due to seasonal differences in self-reporting and recall, but if it’s true, is weight loss in the spring more successful than the fall?

Another important aspect of weight loss to consider is seasonal variability in energy expenditure.

The investigation from the Framingham Heart Study (6) also observed seasonal variation in physical activity, including common activities such as gardening, carpentry, lawn mowing, golf and running for men, and gardening, swimming, health club exercise, dancing and bicycling for women. Not surprisingly, people residing in the Northeast are less inclined to engage in outdoor physical activity. This sedentary lifestyle in the winter may partly explain the reason why people tend to be the heavier in the winter! (7)

Newer studies are investigating more complex physiologic changes that might interfere with energy balance. Recent observations in humans suggest that cold exposure may induce the conversion of white adipose tissue to more metabolically active brown-like adipose tissue (8). This ‘beiging’ effect of cold exposure could potentially have clinical implications for diabetes and obesity. Other studies have observed seasonal variability in metabolism and epigenetics as well (9,10). Whether these physiologic differences can override energy imbalance resulting from seasonal lifestyle differences is currently unknown.

To test whether there are seasonal differences in weight loss success we’d ideally test this in a randomized and controlled weight loss trial whereby people are prescribed hypocaloric diets and assigned random start dates. This can also be investigated analytically in previously conducted weight loss cohorts. Various methodologies are available for the assessment of seasonality and those range from simple comparisons across seasons, to simple models such as fitting monthly counts to a sine curve, or more complex statistical models (2).

Despite the little evidence we have so far relating seasonality and energy balance, healthcare providers, including nutritionists, should account for seasonality in their practice, and tailor their dietary (food and fluids) and physical activity recommendations accordingly – it’d be senseless to recommend berries when they are unavailable at stores or outdoor exercise when it’s uncomfortably warm! But perhaps reaching that point of enthusiasm for weight loss is the most important factor predicting weight loss success, so if January 1 is that date when motivation hits in, then so be it!

References:

2.Christiansen CF, Pedersen L, Sørensen HT, Rothman KJ. Methods to assess seasonal effects in epidemiological studies of infectious diseases–exemplified by application to the occurrence of meningococcal disease. Clin Microbiol Infect. 2012 Oct;18(10):963–9.
3.Stamp TC, Round JM. Seasonal changes in human plasma levels of 25-hydroxyvitamin D. Nature. 1974 Feb 22;247(5442):563–5.
4.Evolving U.S. Fruit Markets and Seasonal Grower Price Patterns, by Kristy Plattner, Agnes Perez, and Suzanne Thornsbury, USDA, Economic Research Service, September 2014
5.Bernstein S, Zambell K, Amar MJ, Arango C, Kelley RC, Miszewski SG, et al. Dietary Intake Patterns Are Consistent Across Seasons in a Cohort of Healthy Adults in a Metropolitan Population. J Acad Nutr Diet. 2016 Jan;116(1):38–45.
6.Ma Y, Olendzki BC, Li W, Hafner AR, Chiriboga D, Hebert JR, et al. Seasonal variation in food intake, physical activity, and body weight in a predominantly overweight population. Eur J Clin Nutr. 2006 Apr;60(4):519–28.
7.Visscher TLS, Seidell JC. Time trends (1993-1997) and seasonal variation in body mass index and waist circumference in the Netherlands. Int J Obes Relat Metab Disord. 2004 Oct;28(10):1309–16.
8.Iyengar P, Scherer PE. Obesity: Slim without the gym – the magic of chilling out. Nat Rev Endocrinol. 2016 Feb 26.
9.van Ooijen AMJ, van Marken Lichtenbelt WD, van Steenhoven AA, Westerterp KR. Seasonal changes in metabolic and temperature responses to cold air in humans. Physiol Behav. 2004 Sep 15;82(2-3):545–53.
10.Aslibekyan S, Dashti HS, Tanaka T, Sha J, Ferrucci L, Zhi D, et al. PRKCZ methylation is associated with sunlight exposure in a North American but not a Mediterranean population. Chronobiol Int. 2014 Jul 30;:1–7.