A sweet problem: Princeton researchers find that high-fructose corn syrup prompts considerably more weight gain

Posted March 22, 2010; 10:00 a.m.

by Hilary Parker

A Princeton University research team has demonstrated that all sweeteners are not equal when it comes to weight gain: Rats with access to high-fructose corn syrup gained significantly more weight than those with access to table sugar, even when their overall caloric intake was the same. 

In addition to causing significant weight gain in lab animals, long-term consumption of high-fructose corn syrup also led to abnormal increases in body fat, especially in the abdomen, and a rise in circulating blood fats called triglycerides. The researchers say the work sheds light on the factors contributing to obesity trends in the United States.

"Some people have claimed that high-fructose corn syrup is no different than other sweeteners when it comes to weight gain and obesity, but our results make it clear that this just isn't true, at least under the conditions of our tests," said psychology professor Bart Hoebel, who specializes in the neuroscience of appetite, weight and sugar addiction. "When rats are drinking high-fructose corn syrup at levels well below those in soda pop, they're becoming obese -- every single one, across the board. Even when rats are fed a high-fat diet, you don't see this; they don't all gain extra weight."

In results published online Feb. 26 by the journal Pharmacology, Biochemistry and Behavior, the researchers from the Department of Psychology and the Princeton Neuroscience Institute reported on two experiments investigating the link between the consumption of high-fructose corn syrup and obesity.

The first study showed that male rats given water sweetened with high-fructose corn syrup in addition to a standard diet of rat chow gained much more weight than male rats that received water sweetened with table sugar, or sucrose, in conjunction with the standard diet. The concentration of sugar in the sucrose solution was the same as is found in some commercial soft drinks, while the high-fructose corn syrup solution was half as concentrated as most sodas.

The second experiment -- the first long-term study of the effects of high-fructose corn syrup consumption on obesity in lab animals -- monitored weight gain, body fat and triglyceride levels in rats with access to high-fructose corn syrup over a period of six months. Compared to animals eating only rat chow, rats on a diet rich in high-fructose corn syrup showed characteristic signs of a dangerous condition known in humans as the metabolic syndrome, including abnormal weight gain, significant increases in circulating triglycerides and augmented fat deposition, especially visceral fat around the belly. Male rats in particular ballooned in size: Animals with access to high-fructose corn syrup gained 48 percent more weight than those eating a normal diet.

"These rats aren't just getting fat; they're demonstrating characteristics of obesity, including substantial increases in abdominal fat and circulating triglycerides," said Princeton graduate student Miriam Bocarsly. "In humans, these same characteristics are known risk factors for high blood pressure, coronary artery disease, cancer and diabetes." In addition to Hoebel and Bocarsly, the research team included Princeton undergraduate Elyse Powell and visiting research associate Nicole Avena, who was affiliated with Rockefeller University during the study and is now on the faculty at the University of Florida. The Princeton researchers note that they do not know yet why high-fructose corn syrup fed to rats in their study generated more triglycerides, and more body fat that resulted in obesity. 

When male rats were given water sweetened with high-fructose corn syrup in addition to a standard diet of rat chow, the animals gained much more weight than male rats that received water sweetened with table sugar, or sucrose, along with the standard diet. The concentration of sugar in the sucrose solution was the same as is found in some commercial soft drinks, while the high-fructose corn syrup solution was half as concentrated as most sodas, including the orange soft drink shown here. (Photo: Denise Applewhite)

High-fructose corn syrup and sucrose are both compounds that contain the simple sugars fructose and glucose, but there at least two clear differences between them. First, sucrose is composed of equal amounts of the two simple sugars -- it is 50 percent fructose and 50 percent glucose -- but the typical high-fructose corn syrup used in this study features a slightly imbalanced ratio, containing 55 percent fructose and 42 percent glucose. Larger sugar molecules called higher saccharides make up the remaining 3 percent of the sweetener. Second, as a result of the manufacturing process for high-fructose corn syrup, the fructose molecules in the sweetener are free and unbound, ready for absorption and utilization. In contrast, every fructose molecule in sucrose that comes from cane sugar or beet sugar is bound to a corresponding glucose molecule and must go through an extra metabolic step before it can be utilized.

This creates a fascinating puzzle. The rats in the Princeton study became obese by drinking high-fructose corn syrup, but not by drinking sucrose. The critical differences in appetite, metabolism and gene expression that underlie this phenomenon are yet to be discovered, but may relate to the fact that excess fructose is being metabolized to produce fat, while glucose is largely being processed for energy or stored as a carbohydrate, called glycogen, in the liver and muscles.

In the 40 years since the introduction of high-fructose corn syrup as a cost-effective sweetener in the American diet, rates of obesity in the U.S. have skyrocketed, according to the Centers for Disease Control and Prevention. In 1970, around 15 percent of the U.S. population met the definition for obesity; today, roughly one-third of the American adults are considered obese, the CDC reported. High-fructose corn syrup is found in a wide range of foods and beverages, including fruit juice, soda, cereal, bread, yogurt, ketchup and mayonnaise. On average, Americans consume 60 pounds of the sweetener per person every year.

"Our findings lend support to the theory that the excessive consumption of high-fructose corn syrup found in many beverages may be an important factor in the obesity epidemic," Avena said.

The new research complements previous work led by Hoebel and Avena demonstrating that sucrose can be addictive, having effects on the brain similar to some drugs of abuse. 

In the future, the team intends to explore how the animals respond to the consumption of high-fructose corn syrup in conjunction with a high-fat diet -- the equivalent of a typical fast-food meal containing a hamburger, fries and soda -- and whether excessive high-fructose corn syrup consumption contributes to the diseases associated with obesity. Another step will be to study how fructose affects brain function in the control of appetite.

The research was supported by the U.S. Public Health Service.

Back To Top

Physician's First Watch for August 18, 2009
David G. Fairchild, MD, MPH, Editor-in-ChiefPhysician's First Watch for August 18, 2009

Chinese Herb Appears Better Than Standard Treatment for Rheumatoid Arthritis 

U.S. researchers randomized some 120 adults with active rheumatoid arthritis to receive the extract (180 mg) or sulfasalazine (2 g) daily for 24 weeks. Participants were allowed to use stable prednisone dosing (up to 7.5 mg/day) but not disease-modifying antirheumatic drugs.

In intent-to-treat analyses, significantly more patients assigned to TwHF versus sulfasalazine achieved at least a 20% improvement in arthritis symptoms (65% vs. 33%). In analyses limited to the roughly 50% of patients who completed the study, results were similar. Adverse events did not differ between the two groups.

The authors write that three of TwHF's metabolites — triptolide, tripdiolide, and triptonide — may account for its anti-inflammatory and immunosuppressive effects.

I just returned from a conference where everyone was discussing vitamin D. It’s been a hot topic in both conventional and alternative medicine lately because vitamin D deficiency is widespread and seems to be related to so many health concerns: osteoporosis, depression, heart disease and stroke, cancer, diabetes, parathyroid problems, immune function — even weight loss.

Many of today’s conventional clinicians received little to no training in medical school for this problem. They may not be in the habit of testing for vitamin D deficiency or, if they are testing their patients, familiar with treatment. But practitioners from both sides of the aisle are seeing more cases of vitamin D deficiency and awareness is on the rise — one colleague reported that 85–90% of his patients don’t get enough D. And that’s consistent with what we see at Women to Women.

How can this be happening? And what should you do about it for you and your family? The answer isn’t as simple as drinking more fortified milk.

We’ve been testing and treating patients for vitamin D deficiencies for many years, and I know there are effective, natural strategies that work in most cases. Diagnosis is easy, and treatment with supplementation is easy, safe, affordable, and can bring wonderful results. So let’s explore vitamin D’s role in your health and how to determine what you should do.

What does vitamin D do for the body?

This essential nutrient is called a vitamin, but dietary vitamin D is actually a precursor hormone — the building block of a powerful steroid hormone in your body called calcitriol. It’s been known for many years that vitamin D is critical to the health of our bones and teeth, but deeper insight into D’s wider role in our health is quite new.

Vitamin D works in concert with other nutrients and hormones in your body to support healthy bone renewal — an ongoing process of mineralization and demineralization which, when awry, shows up as rickets in children and osteomalacia (“soft bones”) or osteoporosis (“porous bones”) in adults.

Researchers are discovering that D also promotes normal cell growth and differentiation throughout the body, working as a key factor in maintaining hormonal balance and a healthy immune system. It appears that calcitriol actually becomes part of the physical composition of cells, assisting in the buildup and breakdown of healthy tissue — in other words, regulating the processes that keep you well.

What’s more, evidence from studies tracking the prevalence of disease by geography and nationality shows clear links between vitamin D deficiency and obesity, insulin resistance, heart disease, certain cancers, and depression. Since most of these problems take many years to manifest, vitamin D deficiency has been overlooked by many providers for a very long time. I test all of my patients, and have been surprised to find that more than 85% come up with a vitamin D deficiency.

Your body can’t create vitamin D on its own. Instead, it’s designed to make it through sun exposure. In theory, you can make an ample supply of vitamin D with as little as a couple of hours per week in the sun — provided the UVB rays are strong enough. You can also ingest D through food, especially fatty fish like wild–harvested salmon. Plus, lots of foods are fortified nowadays, so vitamin D deficiency should be an easy problem to solve, right? But the truth is, we’re just not getting enough, and so many of us aren’t even close.

Vitamin D requirements

The growing awareness of how much our bodies rely on vitamin D has raised concern that the dietary recommended daily intake values (DRI’s) are woefully obsolete — 200 IU (International Units) a day for adults 19–50 years old, 400 IU for those 51–70, and 600 IU for those over 70. Experts now agree that the DRI’s for vitamin D are way too low, particularly for people who don’t get sufficient sun exposure.

Some studies have shown that adults need 3000–5000 IU per day, and others indicate healthy adults can readily metabolize up to 10,000 IU vitamin D per day without harmful side effects. The European Union’s Scientific Committee on Food lists 2000 IU per day as the safety cut-off, as does the US Food and Nutrition Board. But the latest science strongly suggests most adults should be taking more. What gives? We agree that unless you have testing and monitoring, there is wisdom in keeping the safe upper intake at 2000 IU per day. On balance, the point here is that vitamin D at doses far higher than today’s daily intake values (DRI’s) appears to be safe, to promote optimal health, to reduce the risk of many serious diseases, and even to speed healing for serious health concerns.

Vitamin D supplementation appears beneficial throughout our lifespan, from in utero to advanced age. A recent long-term study indicates that we are at less risk of developing osteoporosis later in life if our mothers had adequate stores on board while pregnant. Another age group needing ample vitamin D is teenage girls living in northern climates, who for much of the year cannot get enough sunlight to make enough vitamin D naturally. Optimal bone growth and accumulation during puberty may be a factor in preventing osteoporosis later on in life, and a new, higher daily recommendation for teenage girls (2000 IU — up from 200 IU) would be wise, particularly in winter.

It’s important to note that we lose some of our ability to synthesize and absorb vitamin D as we age. As we grow older and our skin thins, the amount of the vitamin D precursor (a derivative of cholesterol) in it decreases, too. Women entering perimenopause and menopause, when there can be accelerated bone loss, can slow bone loss by getting enough vitamin D on board. The elderly, who are at increased risk of falls and fractures, also stand to benefit from taking vitamin D. Some studies in the US indicate that supplementation with vitamin D and calcium significantly reduces bone loss and incidence of nonvertebral fractures in women 65 and over. Even in sunny Australia, a two-year study conducted among the elderly showed that supplementation with vitamin D reduced incidence of falls and fractures. (But supplements alone are not enough to protect your bones for life — see our bone health section for more guidance.)

Another consideration is that not all forms of vitamin D are created equally — some are more readily usable (bioavailable). The average healthy body can naturally synthesize about 10,000–15,000 IU of vitamin D3 in the skin within just minutes of sun exposure, without ill effect. We have natural checks and balances that shut off vitamin D build-up once we get enough. When we eat sources of vitamin D, they enter the lymphatic system through the intestines, bypassing the skin’s natural shut-off valve. Nevertheless, recent studies suggest the body can use large periodic doses of oral vitamin D3 every few weeks or so and not become toxic. Still, this is a practice reserved for the therapeutic setting, where the individual is being closely monitored.

Getting back to what happens in the body, both sunlight-generated and dietary vitamin D forms go into circulation and are passed along to the liver, where they get converted into calcidiol. This is the circulating form of vitamin D (25[OH]D, or 25-hydroxyvitamin D) that gets measured by testing labs when you have your blood drawn for a vitamin D test.

Next, calcidiol is converted in the kidneys and other organs into calcitriol. This is biologically active form of vitamin D, also known as vitamin D3 (or 1,25[OH]2D; or simply cholecalciferol). This is the form that goes to work by attaching itself to vitamin D receptors present throughout the body. Today we know there are vitamin D receptors in some three dozen different target organs in the body! Researchers have also recently found that in addition to being converted in the kidneys to this active form, calcidiol is converted into calcitriol in about ten other organs in the body — the lymph glands and skin tissue, too, for example. These discoveries are exciting because they lead us to understand how important vitamin D is for whole-body wellness, not the least of which include prevention — and treatment — of certain types of cancer.

But you don’t need to remember a lot of forms and formulas to appreciate what this powerhouse vitamin/hormone has to offer you. The bottom line is, we still don’t fully understand all the mechanisms behind vitamin D’s actions and forms in the body — we just know our bodies rely on a certain amount and that many of us aren’t getting enough. The truth is that adequate levels are probably highly individualized and depend on a variety of factors. To know whether you’re D–deficient, you need to get a blood test from your healthcare practitioner.

How do I know if I’m getting enough vitamin D?

Awareness of vitamin D first took center stage in the early part of the 20th century, although it was described in medical writings as early as the 17th century. Children with vitamin D deficiency developed rickets, a condition where the body fails to mineralize bone. This led to the daily dosing of children with cod liver oil, and a movement to fortify milk and cereal with vitamin D as well. By the 1960’s, rickets had become a relatively rare disease.

These days, most commercial milk suppliers fortify their products with vitamin D in the form of ergocalciferol (also known as D2) or cholecalciferol (D3). Some orange juice makers are doing the same, and like many food fads, you can soon expect to see lots of other products claiming to be good for you because they’re fortified with vitamin D. While the amount in these beverages is enough to ward off malnutrition, you’d have to drink gallons a day to reach optimal levels. That’s just too much milk or juice for most adults. And, while a tablespoon or two of cod liver oil a day is still a superb idea, many people won’t touch it — you could say it’s an acquired taste!

In reality, there really is no sufficient dietary source. But let’s not write off vitamin D-fortified foods altogether. A bakery here in the US recently created a new vitamin D-fortified bread, but it contained so much vitamin D they had to go to Europe to test it, where allowable limits are more progressive. The recipe also included calcium carbonate, and the bread was reported to increase lumbar bone mineral density in the elderly patients consuming it. Fortified bread isn’t the way to go for everyone, of course, but it could provide a dietary option to weakly fortified milk and orange juice.

As we now know, sun exposure was critical for sufficient vitamin D to our ancestors. Until modern times, human beings spent a great deal of time outdoors. The origin of our species was subtropical, meaning we naturally got enough sun exposure to generate vitamin D. But as Homo sapiens migrated to less temperate climes this changed. Over many generations, the shift from a hunter-gatherer to an agrarian-based to an increasingly industrialized society also meant less and less time in the sun. Today many of us work inside sealed buildings with glazed windows, and we wear sunblock and drive everywhere in cars instead of walking outdoors. Any glass windows or sunblock with an SPF above 15 will block the UVB rays necessary for vitamin D conversion.

If you live in a region above latitude 40 (a horizontal line that runs from just below New York City west to northern California), then the sun is only strong enough between May and September to trigger the vitamin D conversion (or the converse in the Southern Hemisphere). This means that a large percentage of the population is at significant risk much of the year for vitamin D deficiency. For all these reasons we recommend 2000 IU per day for anyone at or above this latitude, at least from the fall through the spring months. But the ideal course of action is vitamin D testing, since there is so much individual variation. You would really need to see your practitioner and have your vitamin D levels tested before upping your supplemental dose beyond 2000 IU per day.

Vitamin D deficiency symptoms

Vitamin D deficiency may be characterized by muscle pain, weak bones/fractures, low energy and fatigue, lowered immunity, symptoms of depression and mood swings, and sleep irregularities. Women with renal problems or intestinal concerns (such as IBS or Crohn’s disease) may be vitamin D deficient because they can neither absorb nor adequately convert the nutrient.

Vitamin D, menopause, and osteoporosis

As we age, our bodies slowly lose the ability to mobilize vitamin D, a process that lowers our calcium absorption rates. This creates a higher risk of osteoporosis, particularly in post-menopausal women.

We’re not sure how sex hormones affect vitamin D conversion, but women seem to have a harder time stimulating the mechanism that builds bone tissue when their estrogen levels are reduced.

Calcium is clearly an important co-factor to vitamin D, and may lose efficacy if vitamin D is deficient or estrogen levels are low, as vitamin D appears to be the more critical factor in bone health. A recent study by scientists at the University of Massachusetts found that a diet rich in calcium and vitamin D can help control some symptoms of PMS, such as tearfulness, anxiety, and irritability.

What does this mean? No one knows for sure, but it is more evidence that all the systems of the body are connected and we can’t look for easy answers in one place.

Vitamin D and weight loss

I’m sure many of you have seen the “diet with dairy” ads launched by the American Dairy Council. Some studies have shown that weight loss does occur with an increase in calcium intake, while others appear to refute this. Since vitamin D is directly involved in calcium absorption, it stands to reason that vitamin D is also a factor in how the body regulates weight.

Moreover, people who have a reduced capacity to mobilize vitamin D often weigh more and have more body fat than those with full capacity. In the past 20 years multiple studies have shown a correlation between higher blood levels of vitamin D and leaner body mass.

To my thinking, what seems essential for us to understand here is the vitamin D connection with insulin resistance. Vitamin D deficiency may contribute to the wide set of disorders associated with metabolic syndrome (syndrome X), as well as to PCOS. In a study published in 2004, the authors saw a 60% improvement in insulin sensitivity in healthy, vitamin D replete adults — and concluded vitamin D was more potent than two prescription medications commonly used to treat type 2 diabetes! But the cadres of drug reps spread out across America are not likely to be reminding your healthcare practitioner about this study. They are not likely to have heard about it!

Clearly, vitamin D seems to be very important in regulating our weight, but we don’t yet understand the mechanism involved or how it relates to our environment and individual biochemistry. Still, there seems to be a correlation between rising rates of obesity and vitamin D deficiency. If you are having difficulty with insulin resistance or weight gain — or can’t keep the pounds off once you lose them — you may want to have your vitamin D levels checked by your healthcare practitioner.

Vitamin D and cancer

Evidence is mounting that vitamin D may protect against some cancers, particularly breast cancer, prostate cancer, and colorectal cancers. In fact, over 60 years of research have shown vitamin D supplementation or sunlight-induced vitamin D conversion to be associated with lower incidence of cancers.

There is also a higher incidence of breast cancer in northern climates, but whether that is associated with lower levels of vitamin D is still speculation. Vitamin D deficiency most certainly affects your immune system because calcitriol actually helps regulate cell division, so adequate levels may help sustain normal cell growth. And stress and other physiological markers can disrupt the function of vitamin D receptors, among others, making us more susceptible to unusual cell activity.

Vitamin D and depression

Another area of vitamin D research is its relationship to depression. Seasonal affective disorder, or SAD, is a situational mood disorder brought on by decreasing daylight in the winter months. High doses of vitamin D during these months have proven to be a very effective natural remedy for SAD, leading most practitioners to believe that normal neurotransmitter function depends in part on adequate vitamin D synthesis.

Vitamin D levels are inversely related to those of melatonin, another mood-regulating hormone. Melatonin helps modulate your circadian rhythms, with darkness triggering melatonin secretion by the pineal gland within your brain, bringing you down gently at night for sleep. Insomnia, mood swings and food cravings are influenced by melatonin. Sunlight shuts melatonin production off, while triggering release of vitamin D — that’s why doctors recommend getting outdoors as a remedy for jet lag.

Most of us can sense the positive influence of sunlight in our own lives by the immediate lift we get from taking a walk outdoors on a beautiful sunny day. Now there may be many factors at work that brighten our mood in such cases, but sun exposure is almost certainly a critical piece. Soaking in the warmth of the sun is one of the most relaxing activities we share with all living creatures — just watch a cat dozing in a beam of sunlight.

Healthy sunbathing — is it possible?

Our bodies are remarkably efficient. During the summer months, even as little as 15 minutes in the sun (without sunblock!) in the early morning and late afternoon is enough for most light-skinned individuals to create an ample supply of vitamin D. Skin with more pigment (melanin) may require up to 40 minutes.

But some say we are trading our longer lifespan for an increased risk of skin cancers, so don’t throw away your sunblock! It’s still important to protect your skin, particularly on your face and scalp, during the sun’s peak hours (11:00 AM – 2:00 PM) by using a lotion with SPF–15 (or higher), preferably PABA–free. Melanoma is a serious condition, and I’m not in favor of increasing your risk with unhealthy sun exposure.

This means taking care, not to be out in the sun unprotected for more than 15 minutes twice a day, in the early morning and late afternoon. If you begin to turn red before 15 minutes, cover up completely or go inside. It is never a healthy practice to burn your skin. It is also not safe to rely on tanning beds as a primary source of vitamin D, because their lamps are usually calibrated to favor UVA rays, not the UVB rays that stimulate vitamin D production. (See our page on tanning beds and vitamin D to learn more.)

I do believe from what I see in my patients here in Maine that the problem is on the rise. But it just makes good “body sense” to allow your skin to do what it already knows how — produce vitamin D with sunlight. What’s more, unlike with supplements, it’s impossible to get a vitamin D overdose from sun exposure.

Understanding your own individual needs and levels of tolerance for vitamin D are important parts of healthy self-care. I would like to think that you wouldn’t just assume that because you live at a far northern (or southern) latitude, or work indoors and don’t get much sun exposure, you’re vitamin D deficient and need supplements. To fully answer that question you would need to see a medical professional and get a blood test. (See our page on vitamin D testing and treatment for more information on testing and avoiding toxicity.)

What you can do to prevent vitamin D deficiency

Vitamin D deficiency may be a pervasive problem — one that we treat with specific therapies at our medical practice — but the best way to protect yourself from any deficiency is to build your health from the bottom up and let your body balance itself. We acknowledge the controversy over whether our primary source of vitamin D should be the sun, diet, or supplements. Which combination is best for you depends on many variables, including your age, nutritional status, and geographic location. In a world where so many of us are at risk of vitamin D deficiency, we recognize each of these sources as valuable. With this in mind we recommend the following steps to prevent vitamin D deficiency:

• Allow yourself limited, unprotected sun exposure in the early morning and late afternoon (no more than 15 minutes for light-skinned individuals, 40 minutes for darker skin) — particularly between May and September if you live in anywhere higher than about 35–40° latitude. (See the World Atlas to check out your latitude!)

• Eat a diet rich in whole foods. Nutrient-dense, fatty fish like mackerel and sardines are good sources of vitamin D. Egg yolks, fortified organic milk and other dairy products, and some organ meats (like liver) are also reasonably good natural sources of D. Because vitamin D is still somewhat of a mystery, we’re not sure which co-factors are important for its absorption, but we can surmise they are most fully present in wholesome food.

• Take a top-quality multivitamin every day to fill in any nutritional gaps, preferably one that includes fish oil. (We’ve designed our own multivitamin that we can offer our patients with confidence. Click here to read about our Essential Nutrients.)

• Take a vitamin D supplement. Supplement additionally with vitamin D3 at 1000–2000 IU daily if you do not get testing (or higher with testing, under the care of your healthcare practitioner). For a long time, vitamin D therapy was being prescribed as vitamin D2. To our thinking, this form has more potential for toxicity and is much less effective than natural vitamin D3. Nowadays vitamin D3 supplements are widely recognized as the superior, more bio-ready form for use in the body. How much you need really depends on your particular needs, so testing is really the best way to go for most people.

• Check with your healthcare professional about vitamin D testing. If you think you may be suffering from vitamin D deficiency, get a blood test and ask for the results. I like to see an optimal value of 50–70 ng/mL. A conventional doctor might think anywhere from 20–50 ng/mL is normal, but that recommendation will soon change as the newest research becomes incorporated into the standard of conventional care. Please see our page on testing and treatment for guidelines and precautions.

• Discuss adding a vitamin D supplement to your diet with your healthcare provider. If you don’t get out in the sun every day for 15 minutes in the early morning and late afternoon, consider supplementing with 1000–2000 IU per day — at least during the winter months! But you may need higher levels to reap all the long-term health benefits vitamin D has to offer you, so talk it over with your healthcare provider. This is so important for women of all ages — especially those over 50. Then be sure to get follow-up testing to monitor your response.

And keep in mind that in the end, optimal health is never about just one thing. Vitamin D is just one component of an ever-changing picture — your health is a work in progress that needs your consistent attention and support.

It may turn out that vitamin D is the key everyone’s been looking for, or more likely an important part of a far greater whole-health picture. But what matters most is how you feel and what works for you. I encourage you to investigate your personal vitamin D level with your medical practitioner as part of a comprehensive approach to your whole health.

To test or not to test — the ABC’s of vitamin D testing and treatment

Recommendations for people who choose to get vitamin D testing — and some guidance for those who don’t

How do I know if I need testing?

Today we know the prevalence of vitamin D deficiency is widespread, and for this reason feel testing is easily justifiable for all people. Everyone stands to benefit from knowing what their levels are and, if not optimal, supplementing their vitamin D3 intake. But we also recognize that for whatever reason, not everyone will choose to get tested.

Still, at the very minimum, people who have or are at higher risk of the following health concerns should seriously consider getting their vitamin D levels tested:

• family history or personal history of cancer
• hypertension (high blood pressure)
• schizophrenia
• depression
• migraines
• epilepsy
• osteoarthritis
• autoimmune conditions (such as lupus, ankylosing spondylitis, multiple sclerosis, rheumatoid arthritis)
• PCOS (polycystic ovarian syndrome)
• diabetes mellitus (both types 1 and 2)
• fibromyalgia
• osteoporosis/osteopenia

In addition, anyone who experiences symptoms of:

• musculoskeletal pain, including joint pain and low back pain
• muscle weakness
• poor balance
• systemic inflammation

What if I decide not to get tested?

There is a wealth of health benefits to be enjoyed when we are vitamin D replete. One way to get there knowingly is through periodic testing and vitamin D supplementation. But if you choose not to get tested, all the benefits of the sunshine vitamin are still available to you. You have two options:

Natural vitamin D production. The freest, most natural way is nature’s own: through limited exposure of your skin to the sun. Without sunblock, your skin can manufacture on average 10,000–15,000 IU vitamin D in a single “pinking” exposure. But this route has its limitations, too. Most obviously, if your skin is very, very light, or if you are at risk of or have a history of melanoma, or if you’re fearful of sun exposure for any reason, this is not a workable option for you. (Note that sunblock with an SPF of 15 or higher will block 100% of vitamin D production.) In addition, sun exposure doesn’t work equally well for everyone. It’s a given that the darker your skin, the more melanin pigment it contains, and the more prolonged sunshine exposure you will need to produce adequate vitamin D. What’s more, our inborn ability to manufacture vitamin D from sun exposure tends to decrease as we age, too, and it’s been found that many elderly folks do not manufacture vitamin D at all well. This is because as we age, the thickness of our skin decreases linearly, along with the amount in the skin of the cholesterol-related precursor to the vitamin D molecule. Recently it has also been found that people who are obese do not as readily generate vitamin D in the skin.

Oral vitamin D supplements. Luckily, almost anyone in these groups can benefit from taking oral vitamin D3. If you are among those at higher risk of vitamin D deficiency and you decide not to have testing, we suggest you take 2000 IU oral vitamin D3 supplementation daily. If after 6 weeks you’re not feeling better, you may very well need more to achieve optimal levels. In this case you will need testing and follow-up with a qualified healthcare practitioner to safely achieve optimal levels.

Here is a list of certain populations who are at higher risk of vitamin D deficiency:

• Those who live above 35–40° latitude — you may only get enough radiation from the sun between May and October in the Northern Hemisphere, and between October and May in the Southern Hemisphere. (Visit the World Atlas website to check out your latitude!)
• Those who do not get out in the sun regularly, those who avoid it altogether, and those who use SPF 15 or higher sunblock
• Dark-skinned people
• Elderly people
• Overweight/obese people
• Teens

What specific test should I request from my healthcare provider?

You want to ask for the test that measures the circulating form of vitamin D:  this is referred to as 25[OH]D, or 25-hydroxyvitamin D.

Do I need to schedule my vitamin D test at a certain time, or together with other tests?

Vitamin D testing is best done:

• at any time when you have not been exposed to UVB light for ~6 weeks, as in late fall through late spring or summer
• after discontinuing vitamin D supplement use for at least 3 days
• when you are at least 4 hours fasting
• together with a test for serum calcium levels (an indicator for toxicity)

What levels are optimal when I get my vitamin D tested?

Most labs here in the US currently have a reference range of 20–100 ng/mL. As you can see from the table below, we use a much narrower range at Women to Women!

Many testing labs are currently reporting a twofold to threefold increase in the number of vitamin D tests being ordered. But even now that many physicians agree that everyone needs to get their levels checked, the risk here is that it you may become just another number, where as long as you fall within the conventional normal range, you’re told you’re just fine.

The reality is that you will not be deriving all the benefits of vitamin D unless your levels are quite a bit higher than the norm. You may want to explain to your practitioner, when talking about your blood test, that your goal is to reach into the higher end of the conventional reference range. The mean value in the US is between 25 and 30 ng/mL, so most people here have values that are well below optimal.

While the “normal” reference range is considered to be anywhere from 20–100 ng/mL, the latest scientific research shows the optimal range for health maintenance is 50–70 ng/mL. At these higher levels numerous health benefits can be gained — better bone strength, mood, energy, hormone performance, inflammation reduction, cancer prevention, and more! (Visit the Grassroots Health website to download a chart showing levels needed to provide preventive and healing benefits.)

For healing more serious medical conditions, some research is showing you may need to keep your vitamin D level up even higher. If you have a serious medical condition such as cancer, we urge you to work with a functional medicine practitioner to reach and maintain the levels most helpful for you as an individual.

How do I know how much vitamin D to take to get replete?

How much supplemental vitamin D3 to take depends on how much is in your blood. And how much your body needs to get your levels higher differs from person to person.

We recommend 1000–2000 IU/day unless you are working with a qualified functional medicine practitioner or nutritionist with regular testing in follow-up. If you are deficient, more than this will likely be necessary, but any supplementation above and beyond 2000 IU daily should only be done in conjunction with periodic testing and under the watchful guidance of a qualified healthcare professional.

Again, if you have a serious medical problem, testing and regular follow-up will be needed.

Should I be worried about vitamin D toxicity? How can I prevent vitamin D toxicity?

For most otherwise healthy people who choose not to test for vitamin D levels, it’s generally okay to supplement with 2000 IU vitamin D3 (cholecalciferol) daily, at least between the fall through the spring months, and even in the summertime 2000 IU per day should be fine if you do not get unprotected sun exposure.

However, we do want you to be aware that there are some precautions regarding vitamin D supplementation. If you have any health condition that predisposes you to high calcium in the blood (hypercalcemia),you should not take vitamin D except under the watchful care of a healthcare provider. These conditions include but are not limited to:

• hyperparathyroidism
• granulomatous disease
• sarcoidosis
• Lyme disease
• lymphoma
• kidney disease

It also includes anyone taking the diuretic known as hydrochlorothiazide (HCTZ), a “water pill” drug used to treat high blood pressure and fluid retention caused by a range of conditions, including heart disease.

What are the symptoms of vitamin D toxicity? Can someone be just hypersensitive to vitamin D?

Rarely, an individual may ingest too much vitamin D, which puts them at risk for a reaction from vitamin D hypersensitivity or toxicity. But most people with vitamin D toxicity do not experience symptoms — which is why we do not at this time recommend using more than 2000 IU per day without regular testing and follow-up.

Symptoms of hypersensitivity may be dizziness, and signs of toxicity may include serious stomach upset, vomiting and excessive thirst. If a woman has any concerns or reactions suspected she should stop use immediately and contact the doctor.

The symptoms of too much vitamin D (hypervitaminosis D) are connected with the consequences of having too much calcium in the blood (hypercalcemia). This occurs once the kidneys’ ability to eliminate calcium is exceeded.

Note that this is not a common problem — thankfully, vitamin D toxicity is rare. Most healthy people would have to take a great deal of oral vitamin D before they would reach toxic levels. Here is a list of the clinical manifestations of vitamin D toxicity:

• anorexia
• weight loss
• weakness
• fatigue
• disorientation
• vomiting
• constipation

At our clinic, whenever we prescribe more than 2000 IU vitamin D daily for a patient, we also prescribe regular retesting, and typically request that their blood calcium levels be checked at the same time, just so there is no question of toxicity. See schedule below.

What about retesting? Do I need it?

This will depend on your medical or health condition, and how much vitamin D supplementation you are taking or if you are being prescribed vitamin D therapeutically. If you are found to be deficient and/or you are supplementing at doses higher than 2000 IU daily, we recommend retesting within 2 weeks to 2 months after initiating supplementation.

Once you attain vitamin D repletion, you can refer to the box below on how to keep your levels optimal.

How can I maintain my vitamin D levels once I get them up to where I want to be?

That’s a wonderful question! The answer will vary, according to your age, skin tone, where you live (latitude), the seasons, and your lifestyle (indoors or outdoors, sunscreen protection, and other aspects of the way you live). It will also depend on other risk factors for vitamin D deficiency, and you may want to modify accordingly. Again, the best way to know is to get tested periodically! Here’s what we do in Maine, where the UVB rays are only strong enough (290–315 nm) between May and September to convert the precursor molecule in the skin to provitamin D3.

Dear Patient,

Did you know that you could be eating all the right nutrients but not absorbing them?

In order to build muscle, strengthen your immune system, and get the energy you need throughout the day, the nutrients you eat have to get absorbed in your digestive tract. If you do not digest the foods you eat first, then they cannot be absorbed into your body. And that requires digestive enzymes.

There’s the problem. There’s something in our modern diet that may be stopping you from producing the digestive enzymes you need.

In four weeks, a high-glucose diet was found to shut down the gene that creates digestive enzymes. Food wouldn’t move through the digestive tract, and it couldn’t be absorbed.1

Digestive enzymes break down the food you eat into vitamins, minerals, and other nutrients so your body can absorb it.

Without digestive enzymes, you can’t take in the nutrients you need to feed your cells. Your cells can’t make the energy they need to stay healthy. When your cells run out of energy, your body breaks down, and you develop disease.

You probably already know what sugar does to you, and worse the biggest culprit is high fructose corn syrup. It is in just about everything you buy at the grocery store. It gives you cravings and makes you hungry all the time.2 You gain weight and become depressed.3 Sugar throws off your hormones and gives you diabetes.4 It feeds cancer cells and increases your chance of having a heart attack.5,6

Let's tak a look at what happens when you stop producing digestive enzymes. Protease, amylase, and lipase are the enzymes that digest proteins, carbohydrates, and fats:

• Protease digests proteins. But parasites, fungus, bacteria, and viruses are protein. Without protease, you have nothing to eat away at them. You lose your defense against intestinal bugs, candida, infections, or viruses.
  
  
• Amylase digests carbohydrates. But amylase also digests things like pus, which is dead white blood cells. Without amylase, you can develop pus-filled infections like abscesses or other skin conditions. Or, you could develop a lung condition.
  
  
• Lipase digests fats. Lipase digests fat and nutrients like vitamin E and fish oil. If you don’t have enough lipase to digest fat-soluble nutrients, you can develop high cholesterol, diabetes, and heart disease.

To make sure you have enough digestive enzymes, keep sugar out of your diet as much as you can:

1. In general, foods that are naturally sweet are okay to eat as they are. Just don’t take food that is not sweet naturally and make them sweet.

2. Choose fresh fruits like strawberries, blueberries, and pears for your sweet treat. These naturally sweet foods come with an added bonus: Fresh fruits increase digestive enzymes in your body.

3. Avoid flavored waters and drinks that contain added sugar. Make your own by adding fresh fruit or cucumber, limes, and lemons to water.

4. If you must sweeten any food or drink, do like we do in the office and just add a little good old-fashioned raw sugar or honey.

5. If that fails, eat sweets in moderation.

6. Come in for our digestive enzyme product. It is easy to take and helps you digest the foods you eat without discomfort.

To Your Good Health,

Dr. Waling