A study of more than 60,000 women found drinking more than two glasses of milk a day significantly upped the risk of the most serious form of the disease.
Dairy products have previously been linked to cancers, including those of the breast and prostate.
The research, by Sweden's Karolinska Institute, is published in the American Journal of Clinical Nutrition.
The best advice is to emphasize a balanced diet which includes plenty of fresh fruit and vegetables.
Dr Kate Law
The researchers followed 61,084 women aged 38 to 76 for around 13 years.
During this time a total of 266 women were diagnosed with ovarian cancer, of whom 125 had serous ovarian cancer.
The researchers found women who consumed more than four servings of dairy products a day had twice the risk of serous ovarian cancer than women who had fewer than two.
They found that milk had the strongest link with ovarian cancer - those women who drank two or more glasses a day were at double the risk of those who did not consume it at all, or only in small amounts.
The reason why milk may increase the risk of ovarian cancer is unclear, but one theory is that lactose, a type of sugar found in milk, may overstimulate production of hormones which encourage tumour growth.
Diet element unclear
Dr Kate Law, of Cancer Research UK, said it was not yet clear how nutrients, or the amount and distribution of body fat affected the risk of developing cancer.
She said: "Previous research has also suggested that a diet rich in whole milk, yogurt and cheese may put women at higher risk of ovarian cancer.
"But the picture is far from clear, as other evidence suggests that women who drink skimmed or low-fat milk might have a lower risk of ovarian cancer."
Dr Law a major study, involving 500,000 people, was currently underway to try to assess the impact on diet on cancer.
"Until more is known about the specific components of diet that influence cancer risk, the best advice is to emphasize a balanced diet which includes plenty of fresh fruit and vegetables."
Around 6,700 women in the UK are diagnosed with ovarian cancer each year.
Taking dairy products out of my diet was the best decision of my life. I never get headached anymore, my skin cleared of spots and I never get colds now.
But what do you eat?
Other sites to check
I have pasted an article (from www.thevegansociety.com) about the udder cruelty of the dairy industry. Please take a few minutes to read.
Cow's Milk - What is it?
Cow's milk is a liquid secreted by the mammary glands of the adult female cow to nourish her young calf until weaned. Before the cow can produce milk, in common with other species of mammal, she must first become pregnant and give birth.
The Modern Dairy Industry
Modern dairy farming has become an intensive industry. To produce maximum milk yields, dairy cows are pushed to their physiological limits through a combination of selective breeding, high-protein feeds, and the latest technology. Along with the production of pigs, chickens and eggs, milk production has become just another factory farm operation.
Specialist breeds of dairy cow suited to local conditions have largely disappeared from our countryside. The high yielding and highly bred Holstein-Friesian, the ubiquitous black and white cow, now makes up 90% of the European's (EU) dairy herd. Herd sizes have increased as dairy production has become concentrated on fewer and fewer farms. 
Milk yields have increased dramatically. In the 1940's, cows were producing an average of 3,000 litres of milk per cow per year. By 1983/84, average milk yields had increased to 4,940 litres, and by 1995, over 6,300 litres per cow per year were being achieved.  The strain of higher milk yield can lead to serious welfare problems such as increased mastitis, lameness, and infertility . The average milking life of a cow has steadily decreased. A cow's natural lifespan could be 25 years. Most modern dairy cows are sent for slaughter at about 5 years old, after only three or four lactations. 
As the UK Government's own welfare advisory body puts it: "Forcing a cow to produce excessively high quantities of milk and thereby causing metabolic stress which leads to early culling is also an important welfare issue." 
Distress to Young Calf & Mother
The harsh reality is that to produce milk, a cow must have a calf. To maximise production, each calf is taken from its mother within 24-48 hours of birth. Calves would naturally suckle for 6-12 months.
Separation is a distressing process as mother and calf form a strong maternal bond. Dairy cow husbandry expert, Professor John Webster described the removal of the calf as the "most potentially distressing incident in the life of the dairy cow". Webster points out that "the cow will submit herself to considerable personal discomfort or risk to nourish and protect her calf".  Examples of this are cows that have escaped and travelled several miles to find their own calf after it has been sold on to another farm. 
Raising the Calves
A proportion of female calves are selected as "herd replacements". Reared for the cowshed, these usually spend their first 6-8 weeks of life confined individually in narrow pens. Taken from their mother, and unable to interact meaningfully with their fellows, these calves suffer behavioural deprivation, which can affect them for life.  Alternatively, calves may be reared in groups. With either method, calves are usually fed by artificial teat or bucket.
The young calf is particularly vulnerable to disease. To help boost the calve's immunity, it is essential that they receive colostrum, the mother's first milk, which contains extra nutrients and antibodies against disease. However, calves born to mothers with long, pendulous udders can have difficulty locating the udder. Each year, about 170,000 calves die within their first month of life. Scouring (diarrhoea) and respiratory infections are common killers. 
Calves can be subjected to a range of painful mutilations. Male calves have traditionally been castrated. In the UK, three methods are used; a rubber ring or other device is used to restrict the flow of blood to the scrotum within the first week of life; so-called "bloodless castration" by physically crushing the spermatic cords and surgical castration, both usually carried out within 2 months of birth. All three methods cause acute pain.  Under these conditions, there is no legal requirement for an anaesthetic to be used or a vet to be present.
Calves are often disbudded to prevent their horns growing, or are dehorned in later life. Both procedures are painful and stressful.  Disbudding involves applying a heated iron to the horn buds of young calves up to about 2 months old. If carried out within the first week, the law does not require an anaesthetic to be used. Dehorning involves cutting off the older animal's horns using a saw, horn shears or cutting wire, and cauterising the exposed blood vessels. Mercifully, an anaesthetic is required by law.
Some female calves are born with one or more extra (supernumerary) teats, which are often removed using surgical scissors.
Unwanted Male Calves
The modern dairy cow has been bred to be so specialised for milk, rather than meat production, that male calves of the pure dairy breed are perceived by many farmers as not being worth rearing for meat. These pitiful calves were those exported from the UK to be reared in cruel veal crates on the European continent. Half a million calves about 2 weeks old were transported over long distances to be reared in a system so cruel it was banned in the UK in 1990.
The live export trade in tiny calves was stopped in the 1990's, due to BSE fears and the worldwide ban on British beef and calf exports. Instead, a Government scheme, the Calf Processing Aid Scheme, paid farmers to have these calves killed when just days old. This scheme was terminated in 1999. Male calves - the unwanted by-products of the dairy industry - continue to be treated like disposable waste rather than as sentient beings. All too often, they are likely to face an early death. Government advice for killing calves on farm is that "a free bullet or shotgun are preferred methods". 
The veal crate is a narrow, solid-sided wooden box in which calves are unable even to turn around, let alone exercise, for the 4-6 month rearing period before slaughter. The UK banned narrow veal crates in 1990 and the EU has now agreed to ban this system by 31st December 2006. Under these new EU rules, calves must be housed either in groups or in individual pens that allow the animals to turn round. Minimum iron content and fibre must be given to all calves over two weeks old.
The Suffering of the Mother
A cow's milk production is caused by the birth of her calf. To maximise production, the modern dairy cow is made pregnant again whilst lactating. She will bear a calf each year until worn out and sent for slaughter. Most dairy cows are inseminated artificially. She will have her first calf when 2 years old. She will continue to be milked for 10 months - but will be made pregnant again in the third month. Only during the final few weeks of this pregnancy will she be dried out and her overworked udder given a rest. The amount of milk produced by the cow in peak lactation is more than 10 times the amount that the calf would naturally drink.
The industry's quest for higher milk yield has imposed great stress on the dairy cow's metabolism. So great that she no longer has the natural capacity to keep up with her over-producing udder. To keep pace, the cow's natural food of grass and herbs is supplemented with high-protein concentrated feeds based on grains, soya and fishmeal, which can result in increased gut and foot problems.
Professor John Webster, in The Welfare of Dairy Cattle, states, "The amount of work done by the cow in peak lactation is immense...To achieve a comparably high work rate a human would have to jog for about 6 hours a day, every day." The Professor sums up the situation in saying, "The modern dairy cow may be compared to a highly tuned racing car designed to run as fast as possible on very high grade fuel. As with Grand Prix cars, the results are, at best spectacular but at least unreliable and at worst catastrophic."
The price of high milk yield can be seen in the serious welfare problems in dairy cows...
Mastitis is a painful udder infection that occurs in all dairy herds. Some 35-40 incidences of mastitis are found per 100 cows.  The bacterial infection causes inflammation and swelling of the udder, which can become hard and hot with an abnormal discharge. Antibiotics are injected into the teats of affected cows to treat the disease.
High-yielding dairy cows are prone to Ketosis, a condition that usually occurs in early lactation. It is brought on by the cow's metabolism having to work too hard to sustain milk production. This causes the cow to metabolise her own body fat to make milk, resulting in excessive amounts of ketone bodies in the liver.  Dairy cow expert, Professor Webster states, "Humans with ketosis and liver damage feel extremely unwell and we may reasonably assume the same for cows."
Lameness is a painful and serious animal welfare issue. The rate of lameness in the UK dairy herd is believed to be 55 cases a year for every 100 cows. High-yielding cows are more vulnerable to lameness due to the metabolic strain they are under.  Another important cause of lameness is the fact that cowsheds built 25-35 years ago were designed for traditional breeds. The longer-bodied Holstien-freisians that now make up the majority of the EU dairy herd are too long for their cubicles. Their back legs are all too often standing in the dunging passage, where the soles of their feet can soften and crack, allowing infection to enter. 
Bovine Somatotropin (BST)
Not content with dairy cows pushed to their physical limits, the genetic engineer has come up with the milk-boosting hormone, Bovine Somatotrophin (BST). BST is a genetically engineered version of the cow's own growth hormone. It is designed to increase milk production by a further 10-20%. Thankfully, BST has been banned for use or sale in the European Union (EU). However, the EU ban does not apply to imports of dairy products (e.g. ice cream) and meat from countries such as the USA where BST is used.
BST is administered by injection and can cause serious health and welfare problems. These include increased mastitis (a painful udder infection), tender and long-lasting swellings at the injection site, and digestive disorders. 
Bovine Spongiform Encephalopathy (BSE) in Cattle & Humans
Intensification of the dairy industry causes great suffering to both cow and calf. Through the disastrous practice of turning natural herbivores (cattle) into carnivores by feeding them meat and bone meal, intensive farming has also precipitated Bovine Spongiform Encephalopathy (BSE) or "Mad cow disease". BSE is an infectious and incurable disease that attacks the brain and nervous system of cattle. The UK has the highest level of BSE in the world, with over 179,500 cases confirmed to March 2001. There is now official recognition that BSE may never be eliminated altogether from the cattle herd. 
BSE belongs to a family of prion diseases, several of which can affect humans. The most commonly known disease in this group among humans is Creutzfeldt-Jakob Disease (CJD), a rare and fatal form of dementia. In 1996, scientists discovered a new strain of CJD that occurs predominantly in younger people, known as variant CJD or vCJD. The most likely origin of vCJD is believed to be human exposure to the BSE agent, for example, through eating infected beef. As of March 2001, 95 cases of vCJD had been discovered in the UK. Like BSE in cattle, vCJD in people is always fatal. 
Dairy Farming & Meat Production - the Link
It is a prerequisite for milk production that cows are kept pregnant. To fully maximise profits, farmers use dairy cows as breeding machines to produce calves for the beef industry and to replace the dairy herd itself. And at the end of her short life, the worn out dairy cow is sent for slaughter. Under measures designed to control BSE, her body will be destroyed. Clearly, the belief that animals are not killed so that humans can drink cow's milk is a myth.
Transportation & Slaughter
The business of killing farm animals has become concentrated into fewer and larger slaughterhouses. This means that animals are transported over long distances on their final journey. These unnecessarily long journeys are implicated in the dramatic spread of the latest outbreak of Foot & Mouth Disease.
At the slaughterhouse, cattle are held in a stunning pen where they are stunned using a captive bolt pistol. They are then shackled by the leg, and their throats slit. After the blood has drained away, the animal's body is dismembered.
Other Systems - Organic Dairy Farming
Some of the basic principles of modern dairying are also found in organic milk production: continual pregnancies, unwanted offspring and slaughter.
13th April 2001