Milk and cancer risk: the truth in fog
I. LIMITMENT OF MILLENNIUM AND CANCAL RISK RISKS
At present, there is much controversy about the increased risk of multiple cancers, such as drinking milk and liver and breast cancer. On the one hand, studies indicate that more dairy intake is associated with higher risks of liver and female breast cancer among adult Chinese. For example, a collaborative study between Oxford University, the Chinese Academy of Medical Sciences and Beijing University in the United Kingdom showed that the overall risk of cancer among people who regularly eat dairy products increased by 9 per cent, the risk of liver cancer increased by 18 per cent and the risk of breast cancer increased by 22 per cent for women. The overall cancer risk, liver risk and female breast cancer risk increased by 7%, 12% and 17%, respectively, for every 50 g of milk per day.
On the other hand, however, there is a view that current scientific research has not found a clear correlation between milk intake and liver and breast cancer risks. It was noted, for example, that one expert had a single study with minimal impact, purely from the point of view of the symptoms. And milk is referred to as “white blood”, rich in high-quality nutrients such as protein, calcium and vitamin D, and adequate intake is good for human health. At the same time, many studies have shown the human benefits of drinking milk, such as promoting growth and development, preventing chronic diseases and treating malnutrition.
The controversy over milk and cancer risks is still ongoing, and more in-depth research is needed to determine whether milk increases the risk of cancer.
Relevant research analysis
(i) Research to increase cancer risk
Studies have shown that frequent consumption of milk can increase the risk of liver, breast and prostate cancer. For example, a joint study by a team led by Professor Huaidong and Professor Chen Xiaoming at the University of England found that 50 grams of milk per day were consumed by adults in China, with an increased risk of liver cancer of 12 per cent and breast cancer of 17 per cent. This can be explained by the fact that large quantities of milk drink to increase the IGF-I growth factor in humans, and that IGF-I is closely related to the higher body and that almost every cancer is associated with IGF-I, which is a key factor in the growth and reproduction of cancer cells. In addition, for men, excessive consumption of pure milk may induce prostate cancer, which may be related to the presence of more estrogen and fat in pure milk. It has been reported that milk, pork and egg food are the main risk factors for prostate cancer among male residents of China, which can lead to symptoms such as men’s urination and even incontinence.
(ii) Research to reduce cancer risk
Available studies indicate that dairy intake may reduce the risk of enteric cancer. Studies compiled by the World Cancer Research Fund have shown that 10 g fibres per day are negatively associated with a 10 per cent reduction in the risk of colon cancer and that, following the diagnosis of non-transferable colon cancer, higher fibre intakes are associated with lower colon cancer specificity and total mortality. In addition, an update in 2018 of the World Cancer Research Fund reviewed 14 studies on dairy and colon cancer, and a dose-response analysis (14859) showed that 400 g dairy products were consumed daily, reducing the risk of colon cancer by 13 per cent. An analysis of the effects of the dose between different dairy products and the risk of colon cancer was observed in 2011 (19 Queue Studies), and it was found that the total quantity of milk and dairy products (rather than cheese or other dairy products) was associated with a reduced risk of colon cancer. For calcium calcium calcium, a summary analysis of 10 studies showed a significant negative correlation with 13 studies (11519 cases) that were included in the dose response analysis, showing a daily intake of 200 mg calcium and a 6 per cent reduction in the risk of colon cancer. There is consistent evidence that calcium is associated with a negative risk of colon cancer. With regard to foods containing vitamin D, an update of the World Cancer Research Fund in 2018 reviewed 15 studies of vitamin D-containing foods and colon cancer, which showed that the risk of colon cancer was significantly reduced by 5 per cent per day, with 100 IU vitamin D ingestion.
iii. Can you drink the milk?
(i) Limitations of research
Most of the current research on the relationship between milk and cancer is observational, which means that they can only find a link between milk intake and cancer risk and cannot directly prove that milk causes cancer. For example, in some studies, while the risk of cancer among people who frequently drink milk has increased, this may be due to other factors not excluded.
First, there may be errors in the information gathered by the dietary questionnaire. It is difficult for many to assess accurately their daily intake of dairy products and may be difficult to distinguish between milk and milk drinks. Second, many other factors may not be excluded from the study. For example, excessive animal protein, refined sugar, etc. may also be associated with breast cancer; alcohol consumption, liver diseases, etc. are also associated with liver cancer.
In addition, there are differences in research results. Some studies indicate that milk increases the risk of certain cancers, while others suggest that the two are not linked and may even reduce the incidence of cancers. This indicates that the relationship between milk and cancer is very complex and is still open.
(ii) Recommendations for dietary guidelines
The Food Guide for Chinese Residents (2022) recommends milk products equivalent to 300 ml or more per day. This is a credible recommendation based on an assessment of the results of several studies and an analysis of the country ‘ s nutritional supply needs.
Milk is rich in proteins, calcium, vitamin A, phosphorus and other nutrients necessary for humans. A modest amount of milk helps to supplement human nutrients. Calcium in milk is a major component of human bones and teeth, and many physiological functions also require calcium involvement. Vitamin A contributes to the maintenance of normal vision and to the maintenance of normal physiological functioning of the immune system.
iv. Mistakes in drinking milk and the right choice
(i) Common fault areas for drinking milk
1. Vegetable calcium is better than milk: many people think that vegetables can also be very good at calcium, so that they can be replaced by milk. In practice, however, while some vegetables, such as spinach and broccoli, contain a certain amount of calcium, the calcium content in milk is more abundant and absorbent. In general, about 100 mg of calcium per 100 ml of milk is present, while the calcium content in vegetables is relatively low and is influenced by substances such as herbacid, and the absorption rate is lower than that of milk.
Plant milk is healthier than milk: some feel that plant milk is healthier than milk. However, while plant milk is an option for lactating intolerant people, it differs significantly from milk in its nutritional composition. Milk is a source of high-quality protein and contains abundant calcium and vitamin D. Plant milk, such as soybean milk, almond milk, etc., is low in protein and mostly does not contain calcium. Although vegetative milk is rich in dietary fibres and contributes to intestinal health, milk is a good source of protein and calcium if it is not lactose-resistant.
3. Hormones added to milk: Many are concerned about hormones added to milk. In fact, milk contains natural hormones, such as estrogens, gestational hormones, etc., but at very low levels and, in general, a proper quantity of milk of good quality does not affect human health. Currently, we have strict rules on the hormonal content of milk, requiring that the hormonal content of milk should not exceed the prescribed limit. Some illegal traders may add illegal hormones to milk, but this is illegal, as is generally not the case for regular-sourced milk.
4. Milk for long conservative periods: It is believed that milk for long conservative periods is due to the addition of preservatives. In fact, there are currently two main methods of milk bactericide, one of which is papillocicide, which requires cold storage and a short-term preservation period of 2-7 days, and the other of ultra-high-temperature bactericide, which heats the milk instantaneously to about 150°C, kills almost all bacteria, often for up to six months or even a year. It is not because of the preservatives that milk is preserved for long periods.
(ii) Choice of different groups
Infant: The best food for the baby is breast milk. If breastfeeding is not possible, formula powder suitable for the infant age can be selected. The formula is scientifically adapted to meet the nutritional needs of infants.
2. Young children: Young children can gradually introduce a suitable amount of milk, but choose full-fat milk to ensure sufficient fat intake to promote brain and nervous system development.
3. Children and adolescents: children and adolescents are at a critical stage in their growth and development, choosing to retain, to the maximum extent possible, the nutritional content of the milk. Whole-fat milk contains a large amount of fat soluble vitamin A, vitamin D, vitamin K and vitamin E, as well as rich calcium for digestion and absorption.
4. Pregnant women: Women during pregnancy need more nutrition and should choose vitamin AD milk. Vitamin AD milk should be selected for vitamin A deficiency in the upper and middle-aged population, due to reduced gastrointestinal function, weak digestive absorptive capacity, severe calcium loss and vitamin A deficiency. Similarly, women during pregnancy may choose vitamin AD milk to meet their nutritional needs and those of the foetus.
Adults: Healthy adults can choose full-fat milk and retain the original nutritional content of milk to the maximum extent possible. For dieters and high blood resins, low-fat milk or defamined milk can be chosen to help control heat.
