The weather is changing. No matter where you are in the country, the days are getting shorter, the air is crisper, and you might have already seen snow. It also means your favorite summer produce is out of season, you have switched from salads to comfort foods, and you’re drinking hot cocoa instead of lemonade.

But don’t let these shorter, colder, and darker days put a damper on your mood, decrease your productivity, or expand your waistline. Despite all these changes happening, be sure to keep your health and wellness routines intact.

Thorne has put together a list of the best measures you should be aware of and follow to help you stay healthy this winter.

1.  Test your vitamin D level

Sunlight is the best source of vitamin D, but it’s scarce in winter. You could be living where there are only eight hours of daylight and most days are overcast. Therefore, it is especially important to be consuming sufficient vitamin D through the winter months. 

Vitamin D regulates two of the body’s immune responses: the innate immune response, which your body uses to identify pathogens and recruit immune cells to attack them, and the adaptive immune response, where your immune cells have a “memory” that elicits an enhanced response to a previously identified pathogen.

Very simply put, vitamin D is needed to support your body’s immune responses any time, but especially during the winter “bug” season.

Research shows that individuals who have lower vitamin D levels (less than 30 ng/mL) are more likely to self-report recent upper respiratory tract symptoms, like sneezing, runny nose, or congestion, compared to those with adequate levels.1

Most adults should try to obtain and maintain a vitamin D level of 40 ng/mL, which is considered optimal; and athletes should aim for an even higher level.2

You should make sure your daily diet has plenty of fatty fish, like salmon or tuna – and cheese, egg yolks, and fortified milk are other good sources of vitamin D. One interesting study found that wild-caught salmon has much more vitamin D per serving than does farm-raised salmon (988 IU versus 250 IU per 3.5 ounce serving).3 

Vitamin D3 levels in some common foods (not including foods, like milk, that are fortified with additional D.

Foods Containing Vitamin D3

Serving Size 

Average Vitamin D3 Content

Wild-caught salmon

3.5 ounces (100 grams)

988 IU

Farm-raised salmon

3.5 ounces (100 grams)

250 IU

Fresh herring

3.5 ounces (100 grams)

1,628 IU

Pickled herring

3.5 ounces (100 grams)

680 IU


3.5 ounces (100 grams)

272 IU


3.5 ounces (100 grams)

600 IU


3.5 ounces (100 grams)

360 IU

Cod liver oil

1 teaspoon

450 IU

Canned light tuna

3.5 ounces (100 grams)

236 IU


3.5 ounces (100 grams)

320 IU


3.5 ounces (100 grams)

152 IU

Egg yolk (from indoor raised chicken)

1 yolk

18-39 IU

Egg yolk (from free-range, pasture-raised chicken)

1 yolk

3-4 times the amount from an indoor chicken

Egg yolk from a chicken fed vitamin D-enriched feed

1 yolk

as much as 6,000 IU

Diet may not be enough depending on how well you absorb and utilize what you eat, which is why testing during the winter season is advisable. So consider your lifestyle, geographical location, the time you spend in the sun, your skin color (darker pigmented skin is not as efficient at making vitamin D), and your starting vitamin D level; then consider whether you need to supplement with additional vitamin D to support healthy vitamin D levels this winter.

2.  Maintain hydration

Maintaining hydration during winter has its difficulties. Thirst sensation, sweat levels, urine volume, and air humidity all tell you you’re not thirsty. However, your blood still requires the proper fluid volume to maintain blood pressure, circulation, temperature control, and immune support.

A normal fluid volume supports kidney function and its ability to clear your system of toxins and bacteria that linger in your lymph system.

Similarly, a normal fluid volume helps maintain skin health too, which is our body’s first line of defense. Proper hydration helps ward off the flaky, dry skin we usually see on our lips, hands, elbows, and knees during cold, dry weather.

So even if you don’t feel thirsty, that doesn’t mean you are sufficiently hydrated. Simply breathing, because of the humidity of our breath, is one way we lose fluids without even realizing it. Another way we lose fluids during winter is by what is called cold-induced diuresis.

This occurs when colder temperatures force your body to push warmer blood internally, which keeps your organs warm but less heat escapes through your skin.

Your kidneys recognize the increase in blood pressure and produce more urine as a counterbalance; hence, your body is losing fluid.

Monitor your urine color first thing in the morning and then its changes in color and volume throughout the day. Drinking the recommended eight cups of water a day is a starting point.

Aim to drink enough fluids, with electrolytes, to keep your urine color looking like lemonade rather than apple juice. Although it’s always tempting during the holiday season, drinking alcohol and caffeinated beverages will dehydrate you further. Avoid high-sugar drinks too, because they have an osmotic effect that pulls water from your GI tract. 

3.  Test your salivary cortisol levels

The winter months coincide with the holiday season. While joyous, it can also be stressful. Traveling, hosting parties, family get-togethers, and holiday shopping can bring feelings of anxiety, mood changes, and changes in normal sleep patterns, all of which can affect your stress hormone levels.

You can measure the effect the holidays on your stress levels by tracking your salivary cortisol, which is an internal marker of stress.

Cortisol is a hormone produced in your adrenal gland (above your kidneys) and is secreted when signaled by the brain’s hypothalamus. Cortisol is normally highest in the morning hours around 8:00 am, and then it decreases during the day to be at its lowest while you are sleeping.

But when cortisol remains high throughout the day and the evening, or is higher than normal in the morning hours, then it may be a sign that your body is reacting adversely to the holiday stresses.

A higher-than-normal cortisol for weeks or months can have a negative impact on your immune response, metabolism, levels of inflammation in your body, electrolyte balance, and even your memory.

Use Thorne’s At-Home Stress Test to measure and track your levels of salivary cortisol (and DHEA, which is an adrenal hormone that helps balance cortisol). 

Through the hectic holiday season, keep yourself calm and on a routine as normal as possible, and ensure that you get proper sleep and nutrition. Help maintain a normal cortisol level by treating yourself to a massage, listening to calming music, and consuming foods high in nutrients like magnesium and omega-3 fatty acids that support the pathways involved in regulating cortisol.

4.  Body weight

The next few months may have you wearing comfy, warm clothes. While you’re bundled up in layers and eating comfort foods that warm your soul, you may not notice the extra weight until you’ve already put it on.

No one wants to get on a scale after the holidays, but by tracking your weight this winter, you may be able to avoid the one pound that the average U.S. adult will gain this season.4

Weight-gain prevention and weight-loss studies show that individuals who weigh themselves more frequently tend to gain less weight, and even lose some weight.5 Weekly, and in some cases daily, weigh-ins at the same time of day might be your best practice.

Write it down or use an app to track it. A few gingersnaps might not tip the scale much, but if you don’t burn those calories on a regular basis, then you’ll notice them on the scale in a month. 

Don’t have a scale? Then pick a snug-fitting outfit to use as your benchmark. Sometimes weight changes are most noticeable by how your clothes fit.  

5. Check your blood levels of hsCRP

High-sensitivity C-reactive protein (hsCRP) is a blood marker that is closely associated with cardiovascular disease risk. It is a protein found in the blood that begins to increase when inflammation begins to increase.

Although hsCRP isn’t directly affected by time of day or month, there is research that shows an increased risk for higher hsCRP levels during winter.

Longitudinal data from 534 adults that measured hsCRP throughout the year found that it was higher in fall and winter compared to summer, with higher seasonal levels during winter observed in women.6

Adverse health outcomes of coronary events are significantly correlated with hscRP, and a large number of these events occur in the winter months. Older individuals and men have a 2.4-fold and 2.5-fold higher risk, respectively, of a coronary artery spasm with an elevated hsCRP level.7 

Although age and gender influence your hsCRP levels, body weight is a major cause of inflammation and associated hsCRP elevation.

If your weight is changing, then you should be monitoring your hsCRP level. Check your latest blood test panel from your health-care practitioner because hsCRP is often part of a standard blood test panel. Diet, supplements, and exercise can work together to help maintain a healthy hsCRP level.

6.  Total number of steps

Counting your steps or engaging in purposeful exercise is one way to fight the negative aspects winter:  potential weight gain, seasonal depression, stress, and tiredness.

The average U.S. adult takes between 4,000 and 18,000 steps each day, but does not meet the recommendation of 150 minutes or more of purposeful daily exercise. Walking at 100 steps a minute is average,8 and adding steps may take time from your day. Plan accordingly.

Aim to get 10,000 steps a day.

Add a fitness tracker to your holiday wish list and make it a game to challenge yourself – increase your totals each week. Crunched for time? Up the intensity and do at least 30 minutes of moderately-intense exercise a day. 


1. Ginde A, Mansbach J, Camargo C Jr. Association between serum 25-hydroxyvitamin D level and upper respiratory tract infection in the Third National Health and Nutrition Examination Survey. Arch Intern Med 2009;169(4):384-390.

2. Ogan D, Pritchett K. Vitamin D and the athlete: risks, recommendations, and benefits. Nutrients 2013;5(6):1856-1868.

3. Lu Z, Chen T, Zhang A, et al. An evaluation of the vitamin D3 content in fish: Is the vitamin D content           adequate to satisfy the dietary requirement for vitamin D. J Steroid Biochem Mol Biol 2007;103(3-5):642-644. 

4. Yanovski J, Yanovski S, Sovik K, et al. A prospective study of holiday weight gain. N Engl J Med 2000;342(12):861-867.

5. Burke L, Wang J, Sevick M. Self-monitoring in weight loss: a systematic review of the literature. J Am Diet Assoc 2011;111(1):92-102.

6. Chiriboga D, Ma Y, Li W, et al. Seasonal and sex variation of high-sensitivity C-reactive protein in healthy adults: a longitudinal study. Clin Chem 2009;55(2):313-321.

7. Hung M-J, Hsu K-H, Chang N-C, Hung M-Y. Increased numbers of coronary events in winter and spring due to coronary artery spasm: effect of age, sex, smoking, and inflammation. J Am Coll Cardiol 2015;65(18):2047-2048.

8. Tudor-Locke C, Craig C, Brown W, et al. How many steps/day are enough? For adults. Int J Behav Nutr Phys Act 2011;8:79.