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【Learn to Use/了解使用】Vitamin D: 7 things to know before you take supplements 维生素D:服用补品前要知道的7件事。

【Learn to Use/了解使用】Vitamin D: 7 things to know before you take supplements 维生素D:服用补品前要知道的7件事。

KNOWN AS THE “SUNSHINE PILL” for its supposed ability to mimic the effects of sunshine on health, vitamin D supplements are a billion-dollar industry.

People take vitamin D supplements for a variety of reasons, mental and physical. Some take it if they feel sad, perhaps as the result of the winter blues, for example. Others take it because vitamin D supposedly plays a role in bone health.

But before reaching for the pillbox, you need to know these seven facts about vitamin D supplements and how they work.

WHAT IS VITAMIN D AND HOW DOES IT AFFECT HEALTH?

Vitamin D appears to enable the body to absorb calcium and phosphate — both of which are important for bone health and for muscle function. The vitamin influences cell metabolism and growth, as well as overall immune system functioning. Vitamin D is also associated with a healthy gut microbiome.

The United States' Centers for Disease Control and Prevention recommends mothers who breastfeed their babies supplement their children with vitamin D, and that those who feed their babies infant formula also use formula that contains vitamin D. That is because too little vitamin D is associated with rickets, a condition that is characterized by soft or weak bones.

Beyond bone health, there is evidence that vitamin D plays a role in cancer, too. One study found vitamin D supplementation reduces cancer mortality by 25 percent. The idea is that vitamin D may influence tumor biology, making them less aggressive and less likely to proliferate.

Vitamin D deficiency can result from various problems, like inadequate Sun exposure, digestive problems, and kidney issues. Symptoms may include mood changes, bone loss, fatigue, and muscle, joint, and bone pain.

DOES VITAMIN D AFFECT MENTAL HEALTH?.

Different experts have different perspectives on this. As Inverse previously reportedKathleen Holton, associate professor at American University and a nutritional neuroscientist, says low vitamin D can disrupt normal neurotransmission, and that in turn can lead to mental illness.

Others are more cautious about drawing conclusions. Margherita Cantorna, medical microbiologist and immunologist at Pennsylvania State University, tells Inverse that human brain cells have vitamin D receptors, suggesting that vitamin D is important. But there haven’t been sufficient studies in humans to determine what exactly this means for mental health, she says.

WHERE DOES VITAMIN D OCCUR NATURALLY?

Vitamin D is found in certain foods, including oily fish, mushrooms, eggs, and foods that have been artificially supplemented to contain vitamin D, like milk. The body also produces its own vitamin D when exposed to sunlight.

The way it works is that when sunlight touches our skin, we produce of vitamin D through the conversion of cholesterol in our skin cells, according to researchers at Yale University.


DO VITAMIN D SUPPLEMENTS WORK?

There is plenty of debate about vitamin D supplementation, and about the role of vitamin D in human health.

Vitamin D is most famous for promoting bone health, but a recent scientific review published in 2018 concluded that vitamin D supplementation did nothing to increase bone mineral density or to decrease bone fractures in people who already had normal vitamin D levels.

But according to the National Institutes of Health, vitamin D supplements are an effective way to raise blood vitamin D levels — if needed.

“Whether vitamin D supplements 'work' depends on whether you are deficient, low, or adequate in vitamin D,” Paul Thomas, a nutrition scientist who works with the National Institutes of Health Office of Dietary Supplements, tells Inverse.

“If you get enough vitamin D from food and Sun, vitamin D supplements should not be expected to provide any additional benefits.”

Thomas says that the recommended daily intake of Vitamin D from all sources is 15 mcg (600 IU) for people from 14-70 years old.

“Adequate [blood] levels range from 50-125 nmol/L or 20-50 ng/mL, depending on how the results are reported,” Thomas explains.

HOW CAN I RAISE MY VITAMIN D LEVELS?

People don’t tend to get enough vitamin D from food alone. Rather, the most important natural source of vitamin D comes from exposure to sunlight. But as people spend more time inside and use sunscreen to ward off skin cancer, vitamin D production catalyzed by the Sun decreases. According to a 2017 study, this may mean more people have vitamin D deficiency compared to earlier times in human history.

The shorter, colder days of winter can also reduce our time spent in the sunlight, and so decrease vitamin D production, leading some experts and doctors to recommend supplementation through the winter months.

The Cleveland Clinic says that 10-15 minutes of sunlight exposure to the face, legs, arms, or back a few times a week may provide sufficient vitamin D.

If you prefer to take a tablet every day, then vitamin D supplements are often affordable and generally considered safe, but recommended dosages vary widely depending on the brand. Whatever you think may be best, speak to your doctor before you take a pill.

HOW LONG DO SUPPLEMENTS TAKE TO KICK IN?

The good news is that it is easy to rapidly increase your levels of vitamin D to healthy levels.

“Your blood levels of vitamin D should rise within days of increasing your intake of this nutrient no matter from what source — supplements, foods, or [adequate] sun,” Thomas says.

WHAT EFFECTS SHOULD I NOTICE?

Here's the catch: Unless you have rickets or another extreme symptom of vitamin D deficiency, then you likely won't notice the difference at all.

If you are very deficient, Thomas says, then “any bone pain and muscle seizures and spasms should subside."

"For the vast majority of people, even those with low but not deficient levels, taking extra vitamin D will not provide any short-term noticeable benefits like feeling better, having more energy, or improvement in mental focus."

To get those kinds of benefits, you may be better looking beyond the pill box and to other health-boosting activities.


维生素D补充剂因其模仿阳光对健康的影响而被称为“阳光丸”,是一个价值十亿美元的产业。

人们服用维生素D补充剂的原因有很多,无论是精神上还是身体上。如果有人感到难过,可能有人会这么做,例如,可能是由于冬天的忧郁。其他人则认为是维生素D在骨骼健康中起作用。

但是在使用药丸盒之前,您需要了解有关维生素D补充剂及其作用原理的七个事实。

什么是维生素D及其对健康的影响?
维生素D似乎可以使人体吸收钙和磷酸盐-两者对骨骼健康和肌肉功能都很重要。维生素会影响细胞的新陈代谢和生长以及整个免疫系统的功能。维生素D也与健康的肠道微生物组有关。

美国疾病预防控制中心建议,母乳喂养婴儿的母亲应为孩子补充维生素D,而那些喂养婴儿的婴儿也应使用含有维生素D的配方。这是因为维生素D与病,以骨骼软弱或无力为特征。

除骨骼健康外,还有证据表明维生素D在癌症中也起作用。一项研究发现,补充维生素D可将癌症死亡率降低25%。想法是,维生素D可能会影响肿瘤生物学,从而使它们的侵略性降低并且扩散的可能性降低。

维生素D缺乏症可能是由各种问题引起的,例如阳光照射不足,消化问题和肾脏问题。症状可能包括情绪变化,骨骼丢失,疲劳以及肌肉,关节和骨骼疼痛。

维生素D是否会影响心理健康?
不同的专家对此有不同的看法。正如《逆向》之前报道的那样,美国大学副教授兼营养神经学家凯瑟琳·霍尔顿(Kathleen Holton)说,维生素D含量低会破坏正常的神经传递,进而导致精神疾病。

其他人则对得出结论更为谨慎。宾夕法尼亚州立大学的医学微生物学家和免疫学家Margherita Cantorna告诉Inverse,人脑细胞具有维生素D受体,这表明维生素D很重要。她说,但是对人体的研究还不足以确定这对心理健康的确切意义。

维生素D在哪里自然发生?
某些食物中含有维生素D,包括油性鱼,蘑菇,鸡蛋和经过人工补充以含有维生素D的食物,例如牛奶。人体在阳光下也会产生自己的维生素D。

耶鲁大学的研究人员说,它的工作方式是,当阳光照射到我们的皮肤上时,我们通过皮肤细胞中胆固醇的转化产生维生素D。



维生素D补充剂有效吗?
关于补充维生素D以及维生素D在人类健康中的作用,存在许多争论。

维生素D以促进骨骼健康而闻名,但最近在2018年发表的科学评论得出结论,补充维生素D对已经具有正常维生素D水平的人没有增加骨骼矿物质密度或减少骨折的作用。

但是据美国国立卫生研究院称,如果需要,补充维生素D是提高血液中维生素D水平的有效方法。

美国国立卫生研究院膳食补充剂办公室的营养学家保罗·托马斯(Paul Thomas)表示:“维生素D补充剂的“工作”取决于您维生素D的缺乏,低下还是足够。”

“如果从食物和阳光中摄取足够的维生素D,则不应期望补充维生素D会带来任何其他好处。”

托马斯说,对于14-70岁的人,所有来源建议的每日维生素D摄入量建议为15 mcg(600 IU)。

“适当的[血液]水平范围为50-125 nmol / L或20-50 ng / mL,这取决于报告结果的方式,” Thomas解释说。

我如何提高维生素D水平?
人们往往不会从食物中获取足够的维生素D。相反,维生素D最重要的天然来源来自日光照射。但是,随着人们在室内花费更多的时间并使用防晒霜来预防皮肤癌,被太阳催化的维生素D产生量减少了。根据2017年的一项研究,与人类历史上的早期相比,这可能意味着更多的人患有维生素D缺乏症。

冬季较短,较冷的日子也可以减少我们在阳光下的时间,从而减少维生素D的产生,导致一些专家和医生建议在整个冬季进行补充。

克利夫兰诊所说,每周几次面对脸,腿,手臂或背部几次阳光照射10-15分钟可能会提供足够的维生素D。

如果您希望每天服用一粒药片,那么维生素D补充剂通常价格合理,并且通常被认为是安全的,但是建议的剂量因品牌而异。无论您认为哪种方法最好,在服用药丸之前都要先咨询您的医生。

补充需要多长时间?
好消息是,很容易将维生素D的水平迅速提高到健康水平。

托马斯说:“无论从哪种来源(补充剂,食物或充足的阳光)摄入,您的维生素D摄入量几天之内,您的血液中维生素D的含量就会增加。”

我应该注意什么效果?
这里有个要点:除非您有病或其他维生素D缺乏症的极端症状,否则您可能根本不会注意到这种差异。

托马斯说,如果你很虚弱,那么“任何骨痛,肌肉痉挛和痉挛都应该消退。”

对于绝大多数人,即使是水平较低但并非缺乏的人,服用额外的维生素D也不会带来任何短期的明显好处,例如感觉好些,精力充沛或精神集中。

为了获得这些好处,您最好将目光投向药丸盒之外,而不是其他促进健康的活动。



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