May 22nd marks the start for British Tomato week, and however you say it - tomayto, tomahto - this versatile and delicious food is good for you. In honour of the gardeners sowing their tomato seeds for this year's crop, here's a quick look at the health benefits of tomatoes and how to get the most out of them.

What's in a tomato?

Tomatoes are packed with fibre and are an excellent source of a variety of nutrients, including;

• Vitamin C
• Lycopene
• Beta-carotene
• Zeaxanthin
• Lutein
• Potassium
• Choline
• Alpha-lipoic acid
• Folic acid.

Many of the nutrients above are antioxidants, which help quash the free radicals that damage cells and contribute to chronic diseases such as cancer. As part of an overall healthy diet that contains plenty of fresh fruits and vegetables, nuts, seeds, whole grains, and legumes, tomatoes may help reduce your risk of developing a variety of health issues.

To get the most of your tomatoes, it's best to cook them before eating. This helps to release some of the carotenoids and increase your absorption of lycopene and other nutrients.

Tomatoes, cancer, and carotenoids

In recent years, tomatoes have been associated with a lower risk of cancers such as prostate cancer, colorectal cancer, and even lung and stomach cancer (Marti et al., 2016).

People who eat the most tomatoes have been found in numerous epidemiological studies to have a lower risk of prostate cancer compared to those who eat the least amount of tomato products. This may be mostly due to the carotenoids found in tomatoes, including lycopene, lutein, zeaxanthin, beta-carotene and alpha-carotene.

Lycopene in particular seems to have a high affinity for cells in the prostate gland, where it helps to defend against cellular damage that can lead to cancerous growth. In one case-control study researchers looked at data from 450 prostate cancer cases matched to 450 controls not diagnosed with prostate cancer (Wu et al., 2004).

The scientists examined the level of carotenoids in the participants' diets and in their blood and divided these people into five groups (quintiles) depending on these levels. Those in the highest quintile for blood levels of carotenoids had a 22-34% lower risk of being diagnosed with prostate cancer compared to those with the lowest blood levels, with lycopene showing the greatest effect.

In people who were aged 65 and over, the highest lycopene blood levels were associated with a 53% reduced risk of prostate cancer, rising to a 57% lower risk if these older adults had a negative family history of cancer. In people under 65, those with the highest blood beta-carotene levels had a 64% lower risk of prostate cancer.

In a Japanese study, carotenoid consumption was associated with a reduced risk of colorectal cancer and polyps in both men and women; by as much as 75% for women who consumed the highest levels of zeaxanthin (Okuyama et al., 2014). High fibre intakes from fruits and vegetables is also associated with a lower risk of this type of cancer.

Tomatoes and heart health

A good intake of antioxidants can also help keep blood vessels happy and healthy, which helps the body to better regulate blood pressure. Potassium and sodium balance also plays a key role in blood pressure management and overall cardiovascular health. In one study, people who consumed 4069 mg of potassium daily had a 49% lower risk of death from ischemic heart disease and a 37% lower risk of death from cardiovascular disease compared to people consuming around 1793 mg per day (Yang et al., 2011). Happily, tomatoes provide both antioxidants and potassium!

Tomatoes also provide fibre and folic acid, which help to keep cholesterol and homocysteine levels in check. This is important for heart health as well as for staving off cognitive decline as we age.

Tomatoes and eye health

The antioxidants in tomatoes are especially helpful for keeping our eyes healthy. Lutein, lycopene and other carotenoids help to protect against ultraviolet radiation damage to the delicate tissues of the eyes, which reduces our risk of developing cataracts and age-related macular degeneration (AMD), the leading cause of sight-loss in adults. 

In the much talked about study known as AREDS (Age-Related Eye Disease Study), researchers found that people who consumed high levels of lutein and zeaxanthin had a 35% lower risk of neovascular AMD (San Giovanni et al., 2007).

Other health benefits of tomatoes

We've already mentioned that tomatoes provide a good source of fibre, so it shouldn't be a surprise that they're a great food for digestive health. The fibre in tomatoes can also help slow down the release of sugars into the bloodstream, making it easier for the body to regulate blood glucose levels. This can help lower the risk of developing diabetes or complications from the disease.

Tomatoes are also great for the skin! They not only offer a wealth of antioxidants that help keep free radical damage at bay, they also support collagen synthesis thanks to their high vitamin C content.

And, thanks to their choline and folic acid content, tomatoes even support brain health, making them the smart choice every week, not just during British Tomato Week.

References

Wu, K., Erdman, J.W. Jr., Schwartz, S.J., et al. (2004). Plasma and dietary carotenoids, and the risk of prostate cancer: a nested case-control study. Cancer Epidemiol Biomarkers Prev, Feb;13(2):260-9.

Martí, R., Roselló, S., Cebolla-Cornejo, J. (2016). Tomato as a Source of Carotenoids and Polyphenols Targeted to Cancer Prevention. Cancers (Basel), Jun 20;8(6). pii: E58.

Okuyama, Y., Ozasa, K., Oki, K., et al. (2014). Inverse associations between serum concentrations of zeaxanthin and other carotenoids and colorectal neoplasm in Japanese. Int J Clin Oncol, Feb;19(1):87-97.

Yang, Q., Liu, T., Kuklina, E.V., et al. (2011). Sodium and potassium intake and mortality among US adults: prospective data from the Third National Health and Nutrition Examination Survey. Arch Intern Med, Jul 11;171(13):1183-91.

Age-Related Eye Disease Study Research Group, San Giovanni, J.P., Chew, E.Y., et al. (2007). The relationship of dietary carotenoid and vitamin A, E, and C intake with age-related macular degeneration in a case-control study: AREDS Report No. 22. Arch Ophthalmol, Sep;125(9):1225-32.