Carotenoids Flashcards
Carotenoids
Carotenoids belong to the terpene class of phytonutrients, with more than 750 naturally occurring in nature. They are the source of the yellow, orange, and red colours of many plants.
* The most common carotenoids in Western diets are
alpha-carotene, beta-carotene, beta-cryptoxanthin
(pro vitamin A; see ‘Vitamins’ lecture), lutein, zeaxanthin and lycopene
Carotenoids: Food sources
Yellow, orange, and red fruits and
vegetables. Green vegetables.
Lutein and Zeaxanthin: Functions
Eye health
Lutein and Zeaxanthin: Eye Health
- Both collect in the macula of the eye and absorb up to 90% blue light.
- Protect retinal cells from oxidative stress.
- Shown to protect against visual fatigue and improve visual contrast sensitivity.
- Lutein is thought to promote efficient neuronal signalling , improving
- Lutein inhibits NFkB signalling, reducing inflammation associated with eye disorders including uveitis.
Lutein and Zeaxanthin: Eye Health - Therapeutic uses
- Age related macular degeneration.
- Cataracts.
- Diabetic retinopathy.
- Uveitis.
- To support vision and protect against eye strain.
Lutein and Zeaxanthin: Doses
- Lutein 10 mg / day and zeaxanthin 2 mg / day have
shown to protect against age related macular degeneration. - Doses up to 20 mg / day lutein have been used in some research.
- 1 cup of cooked spinach or kale contains anywhere
between 3 and 20 mg of the two carotenoids
combined, with a much higher ratio of lutein. - Carotenoids are fat soluble; consume with a
small amount of fat to increase absorption. - Lightly steaming helps liberate carotenoids
from the cell increasing their bioavailability.
Lutein and Zeaxanthin: Safety
- No toxicities have been reported.
- Safety of supplemental doses during pregnancy and lactation has not been established.
- Dietary intake is considered safe with no reason to moderate intake.
- No drug interactions have been reported.
Lycopene
Lycopene is a fat-soluble red pigment produced by plants. It is a non-vitamin A carotenoid:
Lycopene: Food sources
- Tomatoes (highest source) more abundant in paste and purée.
- Guava.
- Pink grapefruit.
- Watermelon.
- Papaya.
Lycopene: Functions
Anti-cancer
Prostate health
Cardiovascular health
Lycopene: Anti-cancer
- A powerful antioxidant, impedes reactions initiated by free radicals. Prevents oxidative damage to DNA.
- Modulates expression of cell cycle regulatory proteins, inhibiting cancer cell growth.
- Decreases inflammation (which medicates tumour growth) through reductions in COX-2, interleukin-1 and 6 and TNF-α. It also inhibits NF kB.
- Increased intake is associated with decreased risk for several cancer types including prostate, breast, cervix, lung, stomach, pancreas and colorectal.
Lycopene: Prostate health
- Lycopene naturally accumulates in in the prostate.
- Intake has shown to inhibit progression of benign
prostatic hyperplasia and to decrease elevated PSA - Additionally, it has been shown to induce apoptosis and suppress cell growth in androgen sensitive cell lines.
- Increased dietary intake and higher blood levels of
lycopene are linked with lower prostate cancer risk.
Lycopene: Cardiovascular health
- Prevents oxidation of circulating LDLs, reducing uptake by macrophages in the arterial wall, plaque formation
- Intake of tomato juice is linked with improvements in
endothelial dysfunction.
Lycopene: Dosage
- General recommended intake based on current evidence is 8 22 mg / day.
- Therapeutic doses of up to 75 mg / day are used.
- Intake from dietary sources is preferable (synergistic effects of other phytonutrients)
- Lycopene is better absorbed from foods sources
that have been processed using methods such as juicing and cooking (heating). This liberates it from the cell matrix. - Mixing with oils and fats increases bio availability.
Lycopene: Safety
- No toxicities have been reported.
- High intakes can cause skin discolouration; known as lycopenoderma (rare and resolves on discontinuation of lycopene).
- Safety of supplemental doses during pregnancy and lactation has not been established; dietary intake is considered safe.
