Children who took vitamin D supplements during the cold and flu season escaped seasonal flu and asthma attacks, according to a study published in the American Journal of Clinical Nutrition and reported by Reuters.
For the three-month study, done during cold and flu season, researchers from the Jikei University School of Medicine in Tokyo randomly assigned 167 children, ages 6 to 15, to take 1,200 international units (IU) of vitamin D-3 or a placebo each day.
Vitamin D-3 is more readily absorbed and more potent than vitamin D-2 (usually found in multivitamins).
Scientists noted that only 18 children taking vitamin D caught influenza A compared with 31 kids taking the placebo. Overall, the vitamin D group was 58 percent less likely to catch influenza A.
In addition, vitamin D also seemed to suppress asthma attacks in children with a history of asthma. Two children taking the supplement had asthma attacks compared with 12 children taking the placebo.
Based on the study, researchers concluded that vitamin D-3 supplements may reduce influenza A. They also suggested parents check with their pediatricians about giving their children 1,200 IU of vitamin D per day starting in September to prevent asthma and flu during the flu season.
By BJS —
Forty-three percent of patients scheduled to undergo orthopaedic surgery have insufficient levels of vitamin D and two out of five of those patients had levels low enough to place them at risk for metabolic bone disease, according to a study published this month in the October 6th issue of the Journal of Bone and Joint Surgery (JBJS).
According to the National Institutes of Health (NIH) , vitamin D helps the body absorb calcium and is essential for bone growth and bone remodeling. Without sufficient vitamin D, bones can become thin, brittle or misshapen. People can obtain vitamin D in three ways:
•by eating certain types of food (including fish, dairy products, eggs and
•receiving sun exposure; and
“Given the importance of vitamin D in musculoskeletal health and its role in bone healing following orthopaedic procedures, low levels may negatively impact patient outcomes,” said orthopaedic surgeon Joseph M. Lane, MD, study co-author and chief of the metabolic bone disease service at the Hospital for Special Surgery in New York.
All 723 patients in the study had been cleared by a specialist in internal medicine for elective surgery in one of the following orthopaedic service areas: Trauma, Foot and Ankle, Sports Medicine (only ACL and/or meniscal repair), Arthroplasty (only primary total hip and knee replacement), Hand (only distal radial or ulnar fracture) and Metabolic Bone Disease (only vertebral compression fracture).
The researchers found that, of the 723 patients studied,
•411 (57 percent) had normal Vitamin D levels,
•202 (28 percent) had insufficient levels; and
•110 (15 percent) were vitamin D deficient.
“We found that nearly half of the patients who were considered ‘healthy’ enough for surgery had significantly low levels of vitamin D, placing them at risk for poor bone healing, osteomalacia (bone and muscle weakness) or even secondary hyperparathyroidism (increased secretion of the parathyroid hormone) in the most severe cases,” said Dr. Lane, who is also a professor of orthopedic surgery at Weill Cornell Medical College in New York. “This was very disconcerting since vitamin D levels can be determined with a simple blood test and low levels can be easily treated with supplements in just a few weeks.”
When results were broken down by orthopaedic service area, researchers uncovered a surprising finding: Despite having the youngest mean population (age 45 ± 14.9 years), the Sports Medicine group of patients had the second-highest rate of vitamin D insufficiency (52 percent) — exceeded only by patients in the Trauma group (66.1 percent). The remaining groups had insufficiency levels of 40 percent (Hand), 38 percent (Arthroplasty), 34 percent (Foot and Ankle) and 18.6 percent (Metabolic Bone Disease).
The researchers noted that their results are consistent with those of similar studies investigating the prevalence of vitamin D deficiency in the general population, including identification of risk factors including obesity and dark skin tone.
“This study should serve as a wake-up call to orthopedists that vitamin D deficiency is widespread, not necessarily tied to age, sex or background and screening for it should be part of routine pre-surgical care for adults,” said Dr. Lane. “Meanwhile, patients who are planning to undergo any orthopaedic procedure can request a screening (specifically, a blood test called the 25 hydroxy Vitamin D test) or ask to be placed on a medically supervised Vitamin D supplement regimen prior to surgery.”
Study specific details: In a retrospective chart review, Dr. Lane and his colleagues measured Vitamin D levels of 723 patients who were scheduled for orthopaedic surgery between January 2007 and March 2008 and determined the prevalence of normal, insufficient and deficient levels according to the following parameters:
•Normal: equal to or greater than 32 nanograms per milliliter (ng/mL)
•Insufficient: less than 32 ng/mL
•Deficient: less than 20 ng/mL
How much Vitamin D does the skin make? Our skin makes a lot of Vitamin D when we spend time in strong sunlight. With about 5-30 minutes of sunlight exposure of head, face, hands, arms, or legs), our skin can make about 1000 IUs of Vitamin D (Vitamin D is measured in units called “International Units,” or IUs.) Vitamin D is therefore known as “the sunshine vitamin.” However, as you age you can lose your ability to manufacture Vitamin D through sunlight.
How much Vitamin D is enough? The American Academy of Orthopaedic Surgeons (AAOS) and recent research support that the body needs at least 1000 IU per day for good health — depending on age, weight, and growth. Indeed, many people need much more than 1000 IU to keep Vitamin D levels in a good range.
In general, babies (especially mothers who are breastfeeding) and small children should intake at least 400 IU of Vitamin D daily. Children over age 5, adolescents, and adults should get a minimum of 1000 IU of Vitamin D each day. Disclosure: The HSS study was supported by funding from the Cohn Foundation and the Weill-Cornell Clinical Translation Science Center (UL1RR024996-01). Dr. Lane and his co-authors received no compensation for their research.
By Irene Lane, DC Healthy Living Examiner March 4, 2010
Vitamin D deficiencies among young people are more prevalent than one would think. If you adhered to medical advice and shunned the sun for most of your adult life or maintained a strict vegetarian diet, you may be at risk for a vitamin D deficiency. Increasingly, research is revealing the importance of vitamin D as protection against a host of health problems including cardiovascular disease, cognitive impairment, asthma and cancer. Are you at risk?
Dr. Mary Wilkinson, an oncologist / hematologist who practices in Northern Virginia and who has been consistently listed in Washingtonian Magazine as a leading doctor in the Washington, D.C. area says, “The medical community is just realizing that there is a more complex interaction between vitamin D and cellular growth than what has been previously identified. Nonetheless, people who have used sunscreen liberally or have just stayed away from the sun entirely are more likely to have a vitamin D deficiency.”
What are the lifestyle and individual risks for a vitamin D deficiency? Known as the sunshine vitamin, vitamin D is produced by the body in response to sunlight and is essential for strong bones because it helps the body absorb calcium. It is also occurs naturally in a few foods — including fish, egg yolks and fish liver oils as well as in fortified dairy and grain products. But a deficiency can occur for a number of reasons including:
- Following a strict vegetarian diet since the natural sources are animal-based
- Limiting your exposure to the sun
- Having dark skin because the pigment melanin reduces ability to make vitamin D
- Inability for your kidneys to convert vitamin D into its active form
- Inability to absorb vitamin D due to Crohn’s disease, cystic fibrosis or celiac disease
- Having a body mass index of 30 or greater
What are its symptoms? Vitamin D deficiency may be characterized by muscle weakness or bone pain, increased rate of fractures, low energy and fatigue, lowered immunity, symptoms of depression and mood swings and sleep irregularities. Over time, if the deficiency is not detected, osteoporosis, depression, heart disease and stroke, colon or prostate cancer in men, breast cancer in women, diabetes, parathyroid problems, immune system malfunction and weight loss may develop. Dr. Wilkinson adds, “Since we’ve only been measuring vitamin D levels more readily in the last few years, we are unsure if the deficiency causes breast cancer, for example, or if a vitamin D deficiency is merely associated with breast cancer.”
What test confirms the deficiency? The most accurate way to measure how much vitamin D is in your body is the 25-hydroxy vitamin D blood test. In the kidneys, 25-hydroxy vitamin D changes into an active form of the vitamin that helps to control calcium and phosphate levels in the body. Those levels can be measured through the blood test. The normal range is 30.0 to 74.0 nanograms per milliliter (ng/mL). A lower level indicates a vitamin D deficiency. Dr. Wilkinson emphasizes that “being in the middle of the range is very important since we do know that cancer recurrence is associated with both low and high levels of vitamin D. In this case, being in the middle of the range is best.”
How is one treated for the deficiency? Treatment involves getting more vitamin D — through diet, prescription supplements and spending more time in the sun.
How can one prevent the deficiency?
1. Allow yourself limited (no more than 15 minutes) unprotected sun exposure 2. Eat a diet rich in nutrient-dense foods such as fatty fish, egg yolks, fortified organic milk and other dairy products, and organic meats like liver 3. Take a multivitamin that includes fish oil every day 4. Take a vitamin D supplement
By Robert Dominguez
Looks like there’s a scientific reason why “Jersey Shore’s” tan addicts “The Situation” and Pauly D are constantly on the prowl.
Sunbathing boosts the male sex drive.
That’s according to researchers in Austria, who found that testosterone levels in men rise at the same rate as doses of vitamin D, reports Britain’s Daily Telegraph.
Scientists at the Medical University of Graz discovered that men with more vitamin D in their blood had more testosterone than men with less levels of the main male sexual hormone.
Stimulated by exposure to the sun, 90% of vitamin D in the body is produced by the skin. According to telegraph.co.uk, the new study confirms earlier research that just one hour of sunshine can pump up a man’s testosterone level by nearly 70%.
That doesn’t mean that men looking to lift their libidos should go light on the sunblock – you can also get a healthy dose of vitamin D by eating oily fish and meat.
Sharp rise in problem blamed on kids indoors playing computers and parents using too much sunscreen
By Owen Bowcott January 22, 2010
Computer-obsessed children who spend too long indoors and over-anxious parents who slap on excessive sunscreen are contributing to a sharp rise in cases of the bone disease rickets, doctors are warning.
Vitamin D deficiency, which causes the condition, could be rectified by adding supplements to milk and other food, a research team at Newcastle University suggests.
There are several hundred cases of the preventable condition among children in the UK every year, according to a clinical review paper in the British Medical Journal by Professor Simon Pearce and Dr Tim Cheetham.
“More than 50% of the adult population [in the UK] have insufficient levels of vitamin D and 16% have severe deficiency during winter and spring,” they say. “The highest rates are in Scotland, Northern Ireland and northern England. People with pigmented skin are at high risk as are the elderly, obese individuals and those with malabsorption.”
Most vitamin D is synthesised in the body by absorption of sunlight. Some comes from foods such as fish oil. People with darker skins need more sunlight to top up their vitamin D levels.
One of the main reasons for the reappearance of rickets – once considered a disease of the industrial poor in 19th-century cities – is the changing ethnic makeup of the population, Pearce explained.
The most commonly affected are people of Asian or African descent who live in northern cities. He has examined cases among young Somali speakers who live in east Newcastle. But changing lifestyles are also contributing to lowering vitamin D levels in the general population.
“Some people are taking the safe sun message too far,” Pearce said. “It’s good to have 20 to 30 minutes of exposure to the sun two to three times a week, after which you can put on a hat or sunscreen.
“Vitamin D levels in parts of the population are precarious. The average worker nowadays is in a call centre, not out in the field. People tend to stay at home rather than going outside to kick a ball around. They stay at home on computer games.”
Pearce has written to the Department of Health proposing that vitamin D is added to milk. It is already added as a supplement to artificial baby milk. He has also asked the Royal College of Paediatrics to record cases of rickets but said figures were not being collected.
“A more robust approach to statutory food supplementation with vitamin D (for example in milk) is needed in the UK,” the paper concludes.
Meanwhile, figures obtained by the Tories show the number of patients leaving hospital with malnutrition has hit record levels in the last year. Those affected are primarily elderly people. The NHS figures show that last year 175,000 people were malnourished on entry to hospital but nearly 185,500 were in a similar condition on discharge, meaning more than 10,000 patients were more malnourished after medical treatment.
Low levels of vitamin D in lymphoma patients are associated with cancer progression and even death, according to findings from a Mayo Clinic and University of Iowa study reported by ScienceDaily.
“These are some of the strongest findings yet between vitamin D and cancer outcome,” said lead investigator, Matthew Drake, MD, PhD, an endocrinologist at Mayo Clinic in Rochester.
Researchers studied 374 newly diagnosed cancer patients suffering from diffuse large B-cells lymphoma (a fast-growing, aggressive form of non-Hodgkin’s lymphoma) and found half had vitamin D deficiency. Patients deficient in vitamin D had a greater risk of cancer progression and were more likely to die than patients with optimal vitamin D levels.
“The exact roles that vitamin D might play in the initiation or progression of cancer is unknown, but we do know that the vitamin plays a role in regulation of cell growth and death, among other processes important in limiting cancer,” Drake said.
These findings support the growing connection between vitamin D and cancer risks and outcomes as well as reinforce other field research about the vitamin’s overall health benefits, Drake added.
Vitamin D is obtained from sunlight and converted into its active form by the skin. It is also found in food (naturally or fortified as in milk) and is available in supplement form.
If this vitamin isn’t in your medicine cabinet, it probably should be.
By Linda B. White, M.D.
What do the following conditions have in common: osteoporosis, multiple sclerosis, high blood pressure, diabetes and cancer? Give up? Experts suspect that insufficient levels of vitamin D raise your risk of getting these diseases. Unfortunately, most of us probably are vitamin D deficient.
About all I was taught in medical school is that vitamin D keeps bones strong. Recently however, this area of study has exploded as scientists uncover the vitamin’s far-reaching effects. Because it increases calcium levels, vitamin D indirectly fortifies bones and teeth. It also regulates cells all over the body, which explains vitamin D’s disparate roles, such as influencing insulin production and immune function, as well as helping prevent inflammation and cancer.
The scary thing is that vitamin D deficiency appears to be quite common. A recent British study found that 87 percent of volunteers had low blood levels of the vitamin in winter and spring, and 61 percent had low levels in summer and fall. Why the seasonal variation? Our chief source of vitamin D is sunshine.
Why We’re D-ficient
In response to ultraviolet B (UVB) rays in sunlight, our skin transforms a derivative of cholesterol normally found in the skin into vitamin D3 (cholecaliferol). The liver, kidneys and other tissues further activate this molecule. Given that the skin is a veritable vitamin D factory, why is deficiency so rampant? History — ancient and recent — holds the answers.
Humans evolved near the equator and spent days outdoors, allowing the skin to generate ample amounts of this vitamin. About 50,000 years ago, some of our ancestors migrated toward the poles, where winter sunlight isn’t intense enough for vitamin D production. However, their diet of vitamin D-rich fish compensated for the deficit.
But rickets became prevalent in the 18th century during the Industrial Revolution, when people shifted to indoor labor and the skies darkened with pollution. This manifestation of severe vitamin D deficiency causes skeletal deformities, such as bowed or knocked knees and bony knobs along the ribs, known as rachitic rosary. During the 1930s, the decision to add vitamin D to milk nearly eradicated rickets in the United States. But nowadays, kids and adults drink less milk and more juice and sodas, and sadly, rickets is making a comeback in American children according to a study released last year.
Starting about 30 years ago, another cultural shift deepened our vitamin D deficit: public health campaigns to avoid the midday sun, cover up and apply sunscreen. They were justified attempts to save our skins from sun-induced aging and cancer, but now we’re not making enough vitamin D. These days, vitamin D deficiency has become commonplace, even in the tropics. For instance, a sampling of adults in sunny Honolulu showed that half were low in D.
Of course, we can take supplements, but current government recommendations are cautious — 200 IU a day for young adults, 400 for people 51 to 70, and 600 for those over 70. Vitamin D expert Bruce W. Hollis, M.D., of the Medical University of South Carolina, says such doses might be enough to prevent rickets, but aren’t sufficient to fulfill other important functions.
Most of us don’t even meet these inadequate guidelines. A German study found that 80 percent of sampled adults didn’t get recommended amounts, and nearly 60 percent had low blood levels of vitamin D, a statistic that rose to 75 percent in women over 65 years old. Furthermore, those women with low blood levels of vitamin D were more likely to have high blood pressure, cardiovascular disease and type 2 diabetes.
Results of D-ficiency
So what are the dangers of too little vitamin D in your system? A whole host of chronic conditions.
Weak bones and muscles. Rickets was the first disease tied to vitamin D depletion. This severe deficiency during childhood can prevent kids from reaching their potential for full height and peak bone mass. (Bone mass peaks in early adulthood; after that it slowly declines.)
In adults, vitamin D deficiency can lead to osteoporosis (thin, brittle bones) and osteomalacia (rubbery, demineralized bones). The latter causes bone pain, and both elevate the risk of broken bones.
Additionally, vitamin D deficiency causes muscle weakness and discomfort. One study found that patients with aches and weakness were often severely vitamin D deficient. Hollis says he’s hearing from doctors that vitamin D supplementation often resolves these aches and pains, adding, “A lot of ‘fibromyalgia’ is probably D deficiency.”
Weakened muscles increase the risk of falls and fractures — a dangerous combination for the elderly. The research shows that, although the recommended dose of 600 IU a day doesn’t prevent falls and fractures in older adults, doses over 800 IU do. In fact, consuming 700 to 800 IU of vitamin D a day (plus or minus calcium) could prevent a quarter of hip fractures in older people, according to a study published in the Journal of the American Medical Association.
Cancer. Vitamin D deficiency has been linked to several types of cancer, including breast, prostate, colon and melanoma. In fact, for more than 60 years, research has found that people living at higher latitudes with less exposure to sunlight showed an increased risk of cancer mortality. Adequate vitamin D levels seem to protect against some cancers. In a recent study, researchers followed healthy postmenopausal women whom they assigned to take either 1,400 to 1,500 milligrams a day of supplemental calcium plus 1,100 IU a day of vitamin D3, or a placebo for four years. After the first year, vitamin D supplementation led to a 57 percent reduction in cancer.
Cardiovascular disease. In addition to cancer and bone disease, vitamin D may also be healthy for your heart. Vitamin D levels are inversely associated with the risk of high blood pressure and congestive heart failure. Exposing people with high blood pressure to ultraviolet light has been shown to improve the condition.
Asthma. Preliminary studies show that vitamin D also may help alleviate respiratory problems, such as asthma. According to one study published in the American Journal of Clinical Nutrition, children of mothers with lower intakes of vitamin D during pregnancy are more likely to develop asthma.
Autoimmune disorders. Vitamin D reduces inflammation and plays a role in the maturation of the immune system. Deficiency is common in autoimmune diseases where the immune system attacks normal cells, such as type 1 diabetes, rheumatoid arthritis and multiple sclerosis (MS). Emerging research shows that vitamin D may have a preventive effect. One study examined two large groups of women for 10 years and found a reduced risk of MS was associated with vitamin D supplementation. A study of Finnish children taking 2,000 IU a day (10 times the current recommendation) showed they had a decreased risk of developing type l diabetes. In an analysis of the Iowa Women’s Health Study, women consuming higher levels of vitamin D showed a reduced risk for rheumatoid arthritis.
Mental health. Psychiatrist John Cannell, M.D., founder of the nonprofit Vitamin D Council, says that vitamin D may contribute to several emotional disorders. In a study of elderly people, mood and cognitive skills deteriorated with lower levels of D. Cannell points out that seasonal affective disorder (SAD) is a type of depression whose onset follows the waning daylight of autumn and winter. An Australian study found that vitamin D supplements lifted the mood of people with SAD.
How to Get Enough D
Expose yourself. Your skin can tackle much of your vitamin D needs. If you’re young, fair, scantily clad and near the equator, 10 to 15 minutes of peak sunshine produces 20,000 IUs.
However, Hollis says a dark-skinned person requires 10 times that exposure to make an equivalent amount of D. And a 70-year-old person makes only a quarter of the vitamin D that a 20-year-old can produce. During the fall and winter in higher latitudes (above 37 degrees latitude — San Francisco is just above 37 degrees), the levels of UVB fall below the threshold needed for even a fair-skinned person to produce enough vitamin D. Additionally, complete cloud coverage cuts UV energy in half, and shade reduces it by 60 percent.
Sunscreens also block UVB waves, the wavelength that stimulates the skin’s vitamin D production. According to Michael F. Holick, M.D., Ph.D., of the Boston University School of Medicine, a sunblock with SPF 8 reduces the skin’s vitamin D production by 95 percent. “If you wear sunscreen ‘properly,’ you’ll become vitamin D deficient,” he says.
But what about skin cancer? Despite increased sunscreen usage, skin cancer rates have risen. One reason is that, until recently, sunscreens didn’t impede deeply penetrating UVA light, and presumably, our false sense of security led to more time in the sun and an increase in skin cancer.
What should you do? “Be sensible,” Holick advises. “Know your own skin sensitivity.” For instance, if you turn pink after 30 minutes in the summer sun, thenspending five to 10 minutes (in a bathing suit) in the sun should generate plenty of vitamin D. After that, apply sunscreen, cover up and seek shade.
Eat D-licious foods. Only a few foods contain much vitamin D. Sources of vitamin D include cod liver oil (1,360 IU per tablespoon); oily fish such as salmon, sardines and mackerel (about 350 IU per 3.5 ounces); eggs (about 20 IU per yolk); and fortified milk, soy milk and orange juice (98 IU per 8-ounce serving). (We’re testing pasture-raised chicken eggs for vitamin D as part of our 2007 egg testing project. See October/November 2007 for the initial results. — Mother)
Shiitake mushrooms can be an exceptional source of vitamin D, as noted in research published in Paul Stamets’ book, Mycelium Running. Shiitake mushrooms grown and dried indoors have only 110 IU of vitamin D per 100 grams. But when the shiitakes were dried in the sun, the vitamin D content rose to 21,400 IUs per 100 grams. Even more surprising, when the mushrooms were dried with their gills facing up toward the sun, their content rose to 46,000 IU!
Take supplemental D. Most North Americans can’t maintain healthy blood levels of D from sunlight and good diet. Therefore, many experts recommend 800 to 1,000 IU a day — several times the government guidelines of 200 to 600 IU.
The exact amount depends upon several things. If you’re dark-skinned or spend little time outdoors, you’ll obviously need more than a Caucasian lifeguard. And if you’re already deficient in vitamin D, you’ll need hefty doses just to get your blood levels up to normal.
If you’re pregnant or nursing, you’ll also need more. Hollis and colleagues are currently researching the effects of different vitamin D doses in pregnant women of various races. Until the results of that trial are finalized, he can’t recommend more than 2,000 IU per day.
When asked how much vitamin D they normally take, Hollis says he takes 4,000 IU a day, while Holick says each member of his family takes 1,000 IU of D3 a day. Holick also spends reasonable amounts of time outdoors.
Be aware that many supplements provide vitamin D as ergocalciferol (vitamin D2), rather than cholecalciferol (vitamin D3). D3 is the form naturally occurring in our bodies and is more effective.
No one really knows how much vitamin D might be too much; however, toxicity is exceedingly rare. The Food and Nutrition Board sets the upper level for daily dietary intake at 2,000 IU, though Hollis thinks that’s not enough to maintain health at northern latitudes. Accumulated research demonstrates 10,000 IU of vitamin D3 to be a more realistic upper limit.
Who’s at Risk?
The only way to measure vitamin D blood levels is to check a form of vitamin D called 25-hydroxyvitamin D. Doctors don’t routinely perform this test, and Holick thinks universal screening would be too expensive. If you’re at risk for, or already have symptoms of, deficiency, then you might want the blood test.
Just who’s at risk? Research shows the following populations face greater risk of vitamin D deficiency:
Dark-skinned people. Melanin darkens skin and absorbs UV light, which protects against sun damage and limits vitamin D production. Holick’s research shows that 80 percent of African-Americans studied in Boston over age 65 were vitamin D deficient — at the end of summer!
Northerners. People who live at higher latitudes where winters are long and dark run a higher risk of vitamin D deficiency. Holick notes that even fair-skinned people living above 37 degrees latitude make little vitamin D during the winter.
Older adults. The skin production of vitamin D and its activation in the kidneys declines with age. Further, the elderly typically spend more time indoors. Vitamin D deficiency in this age group contributes to osteoporosis and falls.
Breast-fed infants. Research in Iowa by Hollis and colleagues found that vitamin D deficiency, including severe deficiency, was common among breast-fed infants without vitamin D supplementation. Vitamin D deficiency in nursing mothers is the reason breast milk is D deficient. Unfortunately, early deficiency can have lifelong consequences.
People with intestinal disorders. Disorders that interfere with fat absorption include celiac disease, Crohn’s disease, pancreatic insufficiency, liver disease or cystic fibrosis. Fat-soluble vitamins such as D are absorbed from the intestine with dietary fat, so people with low ability to absorb fat may need vitamin D supplements.
Sun avoiders. People who cover up for religious, cultural or health reasons also run the risk of deficiency. Clothing blocks UVB waves, interfering with or preventing the skin’s formation of vitamin D.
The obese. In a British study, obese people were twice as likely as those of normal weight to be low in vitamin D. Hollis explains it’s because fat sponges up vitamin D and stores it, but doesn’t release it.