Written by Eva Hamrud, PhD
August 2, 2021
17 min read
Topic Review: Supplements
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INTRODUCTION
Chances are that you have some sort of supplement in your kitchen cupboards. Depending on the product that could be tablets, pills or even drops. There are a whole range of substances on offer as well, and they all promise to help our health in some way or another. Vitamin C supplements claim to protect our immune system. Vitamin D pills say they keep our bones strong. Collagen powder is there to keep your skin from sagging. Creatine is the bodybuilder’s new best friend. But do they all do as they claim?
This month we asked scientists and clinicians to share the facts on supplements*.* With vitamin supplements accounting for most of the supplements market, we will focus on them – but not only. Does vitamin C prevent colds? Do we need to take vitamin D pills to avoid bone fractures? Do those ‘anti-ageing’ products actually work? And do we need any supplements if we go vegan?
Here’s what we found.
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META-INDEX
Numbers
4 in 10 Britons that bought supplements last summer.
71% percentage of buyers that purchased a vitamin supplement.
23 bn size of the multivitamin market worldwide in 2017 (dollars).
23% reduction of hospitalisation due to diarrhea in children supplemented with zinc.
2000 micrograms of vitamin B12 recommended for vegetarians per week.
25% percentage of people with iron deficiency.
0.5 teaspoons of iodized salt required to meet daily needs of iodine.
BACKGROUND
Some tips to think about supplements
For supplements in general, there are two important things to keep in mind:
1) A good diet is often all you need
The fact that a substance plays a role in a certain biological process means that supplementing it will probably be helpful if we are deficient. However, if we already get enough of it from our diet or elsewhere, a supplement will not do much at all. Some vitamins aren’t readily available via the diet (Vitamin D), but alot are!
2) What happens in the body when supplements are broken down?
Remember that your body breaks down all the substances you eat to their building blocks, and uses those to build, well, you. In the end, investigate what the supplement eventually breaks down to as opposed to what it is made of.
For simple molecules, like vitamin C (ascorbic acid) what you see is what you get – our body uses it as is. However, collagen is a chain of amino acids (mostly glycine, proline and hydroxyproline). This means that it breaks down into those amino acids as we digest it, just like any other protein source, and only some of them will be used by our body to make collagen that will be inserted into our skin and other connective tissues. In other words, taking a collagen protein supplement may have no advantage over a steak or a lentil dal. In fact, because collagen has such a basic amino acid composition, it is actually a rather poor source of protein compared to the foods we just mentioned, which are more complete.
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THE CONSENSUS
Do multivitamins make you healthier?
Read the full answers to this question here. Many of us take multivitamins frequently in the hope that they will keep us in good health. Multivitamins are the most frequently used supplement (estimates suggest about one in three people regularly take them). They are supposed to contain most essential vitamins and minerals at levels close to recommended daily requirements, but there is no standard regulatory definition of what nutrients or what level of them a multivitamin must contain.
“Adherence to a daily multivitamin regimen has been clearly shown to fill gaps between actual intakes of micronutrients and recommended amounts and to support associated biochemical and cellular functions and structures of our bodies,” writes Prof Jeffrey B Blumberg from Tufts University.
Yet, the evidence is mixed on their benefits. According to Dr Gideon Meyerowitz-Katz from the University of Wollongong, “in general, there does not appear to be strong evidence that multivitamins improve health for people who are otherwise healthy and have a balanced diet. There are some epidemiological studies that suggest an association between multivitamins and good health, but these are likely confounded – essentially, we can see that people who take multivitamins are healthy, but they are also rich, exercise more, smoke less etc, so it’s hard to know if it’s the multivitamin making them healthy or the other aspects of their lives.”
Having said that, so long as they are consumed at the right dose, they might provide benefits for some people. “Supplementation when a deficiency is present or in certain life-stages when dietary requirements are increased (infancy, pregnancy and when breastfeeding, elderly), is recommended to prevent the serious consequences of some of the micronutrient deficiencies,” explains Dr Cornelie Nienaber-Rousseau from North-West University.
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THE CONSENSUS
Do omega-3 supplements help lower the risk of heart disease?
71% Affirmative via 14 experts
Read the full answers to this question here. There are different types of fats depending on their chemical structure, and they also have different effects on our health. Polyunsaturated fats (like those in olive oil or salmon) are considered healthier than saturated fats (like those in palm oil). Among polyunsaturated fatty acids, omega-3 and omega-6 are probably the most common (the name just means the molecule bends at a carbon atom that’s either 3 or 6 carbons away from the ‘omega’ end). Foods like walnuts, soybeans or fatty fish are particularly rich in omega-3.
Omega-3 fatty acids reduce inflammation, and have been suggested to reduce the risk for dementia or heart disease. Some of their benefits “include supporting healthy triglyceride levels, healthy arteries, eye health and vision, cognitive health, and healthy skin and joints,” writes Dr Suzanne R Steinbaum from the Mount Sinai Hospital in New York. Heart attacks and strokes are among the top leading causes of death worldwide, so the fact that many fail to meet the recommended intake of omega-3 should set off alarms.
Omega-3 supplements were thought to help in preventing or treating cardiovascular diseases, according to Dr Mariasole Da Boit from De Monfort University. “However, in recent years, these findings have been challenged by other studies reporting no benefits of omega-3 supplementation on cardiovascular health,” she adds. “Despite a strong association between fish consumption and a reduced incidence of adverse cardiovascular events and mortality, that was first reported in the 1970’s, clinical trials that investigated the effects omega-3 fatty acids (supplements) on these cardiovascular events have largely failed to confirm this initial observation,” writes Prof George E Billman from Ohio University.
Currently, “there is a confusing mix of both positive and negative trials,” agrees Prof Peter McCaffery from the University of Aberdeen. In fact, recent analysis of previous studies revealed no link between supplements and improvements in cardiac health. Why such a discrepancy across studies? “Previous findings derived from trials with higher risk of bias,” argues Dr Da Boit. While some studies reported benefits for body metabolism (even in athletes), more recent work has even linked these supplements to a form of cardiac arrhythmia.
“The results of several big clinical trials did not find that omega-3 supplements reduce the risk of cardiovascular events,” writes Registered Dietitian Carol Haggans from the National Institutes of Health. Yet, supplements could help in people with low dietary intake of omega-3 acids: “omega-3 supplements do lower triglyceride levels and they might have some benefits for the heart, especially among people with lower dietary omega-3 intakes,” she suggests.
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THE CONSENSUS
Do any ‘anti-ageing’ products or supplements actually work?
Read the full answers to this question here. Ageing involves a range of changes in our body including a build up in oxidative stress and the shortening of our chromosomes in our cells’ nuclei. Besides changes in our internal organs (including the brain), our skin also gets more wrinkled, shaggy and pale as we age. Many of us don’t particularly like getting old – and anti-ageing products are becoming incredibly popular and advertised widely on TV and online. But do they work?
Several of our experts warn that the devil is in the details and it all depends on what we consider “ageing”. According to Prof McCaffery, “if you consider anti-wrinkle cream as anti-ageing products then those work e.g. creams based on vitamin A which reduce wrinkles by increasing the production of collagen.” These retinoid-based products can also soften rough patches of skin, even pigmentation or fade age spots, he says.
Now, if you’re looking for something that could actually halt the ageing process, the evidence is much less clear. “A healthy lifestyle will be very likely to increase your lifespan but this is through a decrease in disease frequency, so I would not consider that anti-ageing,” argues Prof McCaffery. Low calorie diets help rodents live for longer but robust evidence from human studies is lacking, he explains.
Is there anything that does work, we hear you ask? For Dr Fiona O’Leary from the University of Sydney, the best protection against ageing is a plant-based diet. “Diets that are high in vegetables, legumes, nuts, fruits, wholegrains with moderate intake of fish and seafood, white meats and healthy oils such as olive oil have been scientifically linked to reduced inflammation, a known contributor to ageing,” she writes. “These healthy diets are high in naturally occurring bioactive compounds that work together to reduce the risk of developing all age-related diseases, including heart disease, cancer and dementia. They also help to maintain a healthy immune system and a healthy weight,” she adds. Several experts agree on this – a healthy lifestyle can help us delay and improve ageing, but in terms of supplements no magic bullet (or tablet) exists for now.
For Dr Lizzy Ostler from the University of Brighton, “it is likely that such supplements will eventually be possible.” However, she argues that would require that “we move on from the medical model that focuses on treating each disease separately (eg cardiovascular disease is managed and treated entirely independently from arthritis) to looking at underlying causes of age-related pathology.”
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THE CONSENSUS
Does Vitamin C boost immune function?
Read the full answers to this question here. Vitamin C is needed for our immune system to function properly. Prof Anitra Carr from the University of Otago writes that “during infections, the body’s vitamin C levels can become depleted”. This substance does not just keep microbes away by supporting the barrier function of the skin. It can also be protective “by acting as an antioxidant to protect the body from the enhanced inflammation and oxidative stress observed during infections, and by supporting various immune cell functions,” she explains.
Unlike other vitamins like A or D, vitamin C dissolves in water rather than fat. This means that it’s easier to secrete and harder to store, which is why we need to keep a constant intake of this substance. Supplements are not needed for maintaining good health, however. “Not if you eat a balanced diet rich in fruits and vegetables,” writes Dr Jens Lykkesfeldt from Copenhagen University. “The amount of vitamin C necessary to prevent scurvy is very low and can therefore easily be obtained from a normal diet,” he adds. It is not just lemons and oranges that are rich in this substance. According to Dr Cornelie Nienaber-Rousseau “citrus fruits, cantaloupe, strawberries, papayas and mangoes are notable sources among fruits. Cabbage-type vegetables, dark green vegetables (like green peppers and broccoli), lettuce, tomatoes and even potatoes are some of the vegetables that provide vitamin C.”
And do vitamin C supplements help against colds? There may be some cases where a vitamin C supplement does help, writes Haggans: “in people exposed to extreme physical stress such as marathon runners, skiers, and soldiers in subarctic areas” as well as “people who get marginal amounts of vitamin C, such as chronic smokers and older adults. However, she adds, “for most people, vitamin C supplements don’t reduce the likelihood of coming down with a cold.” In addition, vitamin C supplements don’t help us recover any faster if we already have a cold. Having said that, “vitamin C supplements taken on a regular basis appear to reduce the duration of the common cold and the severity of its symptoms,” she explains.
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THE CONSENSUS
Is Vitamin D important for bone health?
Read the full answers to this question here. Vitamin D acts as a carrier for calcium which helps its absorption by our body, and in turn calcium is a key mineral for bone health. Among its many functions, calcium is crucial for the macrophages in your bones, called osteoclasts, to degrade old bone material and thus enable renewal.
“Vitamin D is a vital part of the system that maintains healthy bones. Its primary role is to maintain the levels of calcium within our bodies at optimal levels. It does this by helping the calcium in our diet enter our bloodstream and thus reducing the amount of calcium that otherwise be lost in our urine,” writes Prof Bill Ribbans from the University of Northampton. He explains that a number of conditions are linked to low levels of vitamin D, including rickets in children and osteomalacia in adults. “Additionally, both clinical and experimental studies suggest low vitamin D levels can be associated with osteoporosis although the links are not straightforward,” he adds.
Dr Nipith Charoenngam from Harvard writes: “when you have vitamin D deficiency, you do not have enough calcium in your body.” “Then the body tries to compensate by taking calcium out of your bone, causing your bone to become more fragile,” he explains.
For this reason, supplements can be helpful. Although we can synthesise vitamin D ourselves through sun exposure, the amount we get varies. According to Haggans, it depends on various factors “including season, time of day, length of day, cloud cover, and smog. In addition, older people and people with dark skin are less able than others to produce vitamin D from sunlight.” There is the obvious trade off with too much exposure to sun increasing risk for skin cancer, however. “As a general rule, approximately 5–30 minutes of sun exposure, particularly between 10 a.m. and 4 p.m., either daily or at least twice a week to the face, arms, hands, and legs without sunscreen usually leads to sufficient vitamin D synthesis,” she says.
If you choose to take supplements, can you take too much Vitamin D? All the experts we asked said yes. “Signs and symptoms of vitamin D toxicity include increased urination, nausea, vomiting, kidney stone, constipation, confusion and calcification of soft tissues,” explains Dr Charoenngam. An overdose of vitamin D is hard to achieve however, unless you have a genetic hypersensitivity (which is very rare) or overdo it with the tablets. “Interestingly, natural synthesis of vitamin D through brief exposure to the sun will not result in too much vitamin D production. This is because your body will naturally counteract excessive production,” writes Dr Vanessa Meyer from the University of the Witwatersrand in South Africa.
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QUICK ANSWERS WITH CONSENSUS
Do antioxidant supplements work at reducing free radicals? Synthetic antioxidants do scavenge free radicals in the body, which have been implicated in conditions like cancer or heart disease. However, it does not look like antioxidants reduce risk for disease.
Do cranberry supplements prevent urinary tract infections? Cranberry supplements contain a substance that prevents bacteria from sticking to the walls of the bladder and could thus help prevent urinary infections – but the evidence suggests it’s small and they don’t seem to work for treating infections.
Do resveratrol supplements help against heart disease? Despite the hype and the fact that these supplements are beneficial in rodent studies, it is still unclear whether they can help in humans.
Do beta-carotene supplements help cognition? A 2018 review concluded that short term supplementation had no benefits. In the long term, it could provide small benefits but more research is needed.
Are old people more prone to magnesium deficiency? Yes. While body requirements for this mineral remain stable as we get old, absorption worsens and excretion increases, so old people may benefit from supplementation (but talk to your doctor first).
TOP ANSWER
Are vitamin B12 supplements sufficient for a vegan diet?
Heidi Seage: An expert from Cardiff Metropolitan University in Health
Vitamin B12 – otherwise known as cobalamin – is a water-soluble vitamin found in animal by-products, such as meat, fish and dairy. Other sources include fortified cereal, breads and plant milks. People who don’t regularly consume products containing B12 are at risk of becoming deficient. It is recommended that vegans aim to consume at least three micrograms of B12 daily through fortified foods, or by taking a regular B12 supplement.
However, B12 deficiencies can develop for reasons other than diet (e.g. inadequate absorption of vitamin due to an autoimmune disorder such as Pernicious Anaemia), Therefore it is recommended that regardless of dietary intake, if an individual experience symptoms of B12 deficiency (e.g. fatigue, lethargy, breathlessness, mouth ulcers, muscle weakness and problems with memory) that they seek support from their healthcare providers.
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TAKEAWAYS
- Vitamins can be supplemented, but supplements are not normally needed if we follow a balanced diet. They are unlikely to provide benefits unless we are deficient.
- Supplementation is important when a deficiency is present or in certain life-stages when dietary requirements are increased (infancy, pregnancy and when breastfeeding, elderly).
- Too much of a vitamin can be dangerous. It is hard to get an overdose from food but very much possible with supplements, so watch out.
- Like it or not, a healthy diet and exercise remain our best tool for keeping healthy.
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