|Contents and links: Test your supplement needs | How to eat healthily | Vit A | Vit E | Vit C | Vit D | Calcium | Carotenoids | Zinc | Selenium | Interaction with chemotherapy | Phytoestrogens | Fish oils | Probiotics | Chondroitin | Glucosamine | Summary of risks | Summary of benefits | How to take supplements | Book - Lifestyle after Cancer |
In an ideal world a healthy, varied diet should not need supplementing with additional pills tablets or potions. There are situation where selected supplements may help especially after an illness but it is difficult to know what or how many to take. This page discusses the issues of dietary supplements in relation to cancer
Although the concept of a quick fix supplement is attractive, as we all know, life is unfortunately not that simple, especially when considering the integrate genetic and constantly changing biochemical cancer pathways.
Several environmental studies have shown a link between selenium, zinc and some vitamin deficiencies and cancer. There have been some studies showing that correcting a deficiency in a population reduces the risk of cancer. For example, in China were the soil is very low in selenium, one village was given selenium and another a placebo - after 4 years there was a significantly lower incidence of liver cancer in the selenium village.
In the west the evidence is more conflicting difference in the There may be other concerns about supplements compared to concentrating on whole healthy foods. Some of the large trials have shown that upsetting the dietary balance of nature and taking too much of a good thing, may be harmful both in terms of cancer and other important illnesses such a heart disease and strokes. Although there is still much to learn from ongoing studies, I and many enthusiasts have considerable reservations that supplements, in some situation, could do more harm than good.
cancer cells and mice in the laboratory demonstrated an anti-cancer effect after
being fed with vitamin
A. However, in a study involving 10,472
Vitamin C helps DNA sense and repair the damage caused by free radicals, such as hydrogen
peroxide. Convincing experiments in
humans in relation to cancer have either not been conducted, or are
inconclusive. Studies using high dose vitamin C, particularly if given via a
vein (intravenous), caused kidney damage in some individuals.
in the form of calciferol fed to cancer cells and rats in the laboratory,
reduced cancer growth, progression and the formation of new blood vessels.
Humans with sub-optimal levels of vitamin D have been linked with a high risk of
cancer. Clinical studies of high dose calciferol, however, had to be abandoned
however because it dangerously increased serum calcium.
supplements have been evaluated in two human studies at doses of between
1330-1840 mg/day, and showed no benefit or risk of cancer. Two other large
studies at doses >2000 mg/day from food and supplements, actually showed a
significantly higher rate of prostate cancer. Five of nine further questionnaire
surveys associated high intake of dairy food with an increased risk of prostate
and breast cancer, but interpretation of these was complicated by the fact that
high dairy consumption was associated with high fat intake. The detrimental
effect of excessive calcium is thought to lie in the finding that high dietary
calcium can reduce blood and cellular vitamin D levels.
and vitamin D supplements are very useful in the maintenance of bone density and
preventing osteoporosis. Bones are at risk following a number of cancer
therapies. The paragraph in the
‘cons’ section above, however, summarises the concerns with a high calcium
intake on its own. The reasons for the negative effects of calcium are likely to
be its associated with food of high fat content and its tendency to lower
vitamin D levels. Combining calcium
with vitamin D in a supplement will avoid these factors, and in theory may be
safe. Although confirmation of this theory in a clinical trial is required, it
provides some reassurance that it is likely to be safe and can be taken if bone
loss is a concern.
In a laboratory experiment, rats fed with tomato powder, but not those fed with pure lycopene, demonstrated a reduction of their tumour growth. Another large human dietary prevention study combined beta-carotene with retinol (vitamin A). People who started the trial with naturally low blood levels of beta-carotene had lower levels of prostate cancer after years of supplementation. Those people who had adequate blood levels at the start of the study ended up with a higher risk of cancer, particularly prostate. This trial provides a clear take home message, that correcting a natural or acquired deficit is beneficial, but too much of a single anti-oxidant is harmful.
is one of the metals needed to produce the superoxide dimutase (SOD) enzyme
important to defend the body against the attack of dangerous free radicals.
Laboratory experiments have shown that cells deficient in zinc are more likely
to become cancerous. The role of zinc supplements in humans was highlighted in a
study of 50,000 health professionals, 3348 of which developed prostate cancer.
Detailed analysis showed that men who took normal amounts of zinc had the normal
incidence of prostate cancer, but those who took supplemental zinc at levels of
more than 100mg/day, or for long durations, were more than twice as likely to
develop advanced prostate cancer.
eloquent trial, gave 200 micrograms of dietary
selenium or placebo to large group of Americans. After several years, there was
a significantly lower level of lung, bowel and prostate cancer in the selenium
group. Several large ongoing prevention studies are now underway across the
world to try to confirm these findings, and fine-tune the optimal selenium dose
required. Many suspect, however, that the people who would benefit from selenium
supplements are those with a dietary deficiency in the first place. There is
also evidence from studies involving blood / hair samples and toenail clippings,
that many areas of the World have populations deficient in selenium, including
foods containing phytoestrogens are generally healthy, concentrating oestrogenic
elements of food into a pill can be potentially hazardous. Although chapter 5
explains the lack of evidence for and against this, most cancer doctors would
discourage their patients from taking them. This is especially true for
individuals with tumours originating from the breast which can be stimulated to
grow by oestrogens.
interaction with chemotherapy In
recent years it has become evident that some over the counter remedies can
influence chemotherapy drug metabolism leading to reduced effectiveness or
increased toxicity. Unfortunately, patients often do not realise that these
products may interfere with their treatment as there use is mostly not discussed
with their cancer team. Furthermore, as they are usually branded as natural, a
possible harmful interaction is usually not considered. This should be regarded
as an oversight as other research has shown that up to 84% of patients dabble or
regularly take complementary medicines after their diagnosis of cancer.
Amoung the most widely used herbal supplement is
Although the evidence for a number of other complementary therapies is
less robust, potential interactions have been reported with echinacea, grape
seed and gingko (caution with most chemotherapy drugs), ephedra (increases blood
pressure during cancer therapies particularly with sutent and nexevar), kava-
kava (increases the risk of liver damage). In short, supplements are chemicals
and need the body’s metabolic processes to excrete them. As the body is
already under a lot of pressure and there is some evidence that antioxidant,
herbal or vitamin they may interfere with the effectiveness of conventional
therapies, on balance it is best not to take them as they make matters worse.
Cod liver oil is also high in vitamin D which is difficult to take in recommended amounts particularly, in the northern hemisphere. As deficiencies in vitamin D have been linked to cancer, for this reason alone, there may be a place for daily cod liver oil supplements, at least in the winter months.
The most numerous probiotic bacteria normally inhabiting the small intestine are a species of lactobacilli. In the colon, the majority are mainly bifidobacteria. Most probiotic products consist of one or more species of bacteria from one or both of these types.
is by far the most well known species of probiotic, which has led many people to
refer to probiotics simply as "acidophilus". This strain, amongst
other benefits, has been shown to increase levels of interleukin and tumour
necrosis factor, which suppress cancerous tumour growth. Other research has
shown that L.acidophilus alleviates lactose intolerance by producing significant
amounts of the lactose digesting enzyme, and inhibits gastrointestinal pathogens
by producing antimicrobial substances such as acidophilin. It has also been
shown to help conditions outside the gut such as eczema and other skin
inflammatory skin conditions. Chemotherapy agents such as fluorouracil can cause
diarrhoea, which cannot only be uncomfortable, but can also lead to dehydration,
concentration of the drug in the blood stream and generally greater side effects
and risks. A study in 2007 randomly allocated a 100 patients receiving
fluorouracil Lactobacillus acidophilus, and another 50 patients no supplements.
There were no adverse effects in the probiotic group, but the rate of moderate
to severe diarrhoea was significantly better in the lactobacillus group.
This organism usually passes through the digestive system and leaves the body in
the stool, untouched. It has been shown to enhance the digestibility of milk
products and other proteins, and to produce natural antibiotic substances that
specifically target pathogenic bacteria, whilst sparing friendly species. In
another study it was shown to stimulate activity in part of the gut immune
system called the Peyer's patches.
has been shown to inhibit the bacteria Helicobacter pylori (H.pylori) which is
responsible for the creation of peptic ulcers. It has been discovered that
L.salivarius produces large amounts of lactic acid acting as an antibiotic,
inhibiting the growth of H.pylori and reducing the associated inflammatory
response. The first bacteriocin (natural antibiotic substance) to be isolated
and studied at the genetic level, was taken from a strain of L.salivarius.
are indigestible carbohydrates known as oligosaccharides, and feed probiotic
bacteria and encourage their growth. Oligosaccharides are found naturally in
certain fruit and vegetables, including bananas, asparagus, garlic, wheat,
tomatoes, artichoke, onions and chicory. Prebiotics can be taken on their own or
with a probiotic supplement. The most common types of prebiotics available in
supplements are fructooligosaccharides, inulin and galactooligosaccharides.
and Glucosamine These
are complex sugars that are present in the cartilage of joints. They are used
widely to treat arthritis, and are often taken in large quantities by body
builders who are convinced that they would not be able to lift the weights
without extra protection for their joints. Their springy chemical structure
provides much of the resistance to compression of cartilage on weight bearing,
and its loss is a major cause of joint pain and osteoarthritis
appears to be made from extracts of cartilaginous cow and pig tissues
particularly trachea, ear and nose, although alternative sources include bird
and shark cartilage. The dosage of oral chondroitin used in human clinical
trials is usually 800–1,200 mg per day. Since chondroitin is not a uniform
substance, and is naturally present in a wide variety of forms, the precise
composition of each supplement will vary. Chondroitin is under the jurisdiction
of the FDA in the
is a monosaccharide amino sugar found as a major component of the exoskeletons
of crustaceans, but is also found abundantly in fungi and higher organisms.
It is produced commercially by crushing crustacean exoskeletons. Like
chondroitin, glucosamine is commonly used as a treatment for joint pains,
although its acceptance as a medical therapy varies.
Multiple clinical trials in the 1980s and 1990s, all sponsored by the European patent-holder, Rottapharm, were conducted on patients with a wide variety of arthritic problems. Although these trials were small and not particularly well designed, they did show a clear benefit for glucosamine treatment. There was not only an improvement in symptoms, but also an improvement in joint space narrowing on. This suggested that glucosamine can actually help prevent the destruction of cartilage as well as reduce pain. On the other hand, several subsequent studies, independent of Rottapharm, but again small and poorly designed, did not detect any benefit of glucosamine. As a result of the conflicting evidence both for and against glucosamine's efficacy, there remained a debate amongst physicians about whether to recommend glucosamine treatment to their patients.
situation led the prestigious National Institute of Health in the
Summary of concerns with dietary supplements:-
Summary of the potential benefits of dietary supplements
Is there a place for dietary supplements? The concerns above do not necessarily insinuate there is no place at all for supplements. Well designed supplements should have a wide range of essential trace minerals and vitamins at low doses which means it is unlikely to accumulate toxic levels of a single mineral. Others such as fish oils area good source of omega 3 and have been proven to help arthritis and help reduce cholesterol.
The safest way to ensure you take the correct amount and type of dietary supplement is to find out your own bodies current levels and requirements. A number of different tests are available to do this ranging from analysis of blood, urine, saliva, hair or even or toe nails! A number of independent laboratories are now offering tests which can assess your baseline nutritional status.
Test your baseline nutritional status - This will help you decide if supplementts are necessary and if so which types